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Security and Performance FAQs

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Getting Started

Is GNU and Open Source software worth the costs and risks?

It's difficult, if not impossible, to argue against the value proposition of GNU and Open Source software, although some have tried. Due to zero licensing fees, lower administrative overhead, high-quality code, security releases that are distributed in minutes or hours rather than months or marketing cycles, and free online support from thousands of like-minded developers and users, GNU and Open Source offerings are often the best solution. The math is really quite compelling:

Applications Industry Leader Cost
GNU/Linux Yes 0
Apache Web Server Yes 0
MySQL Relational Database Yes 0
PHP Scripting Language Yes 0
Joomla! Content Management System Yes 0
Thousands of Joomla Extensions Varies 0
Support Relative Quality Cost
Joomla! Project Leadership Team High 0
Joomla! Forge High 0
Joomla! Online Forums High 0
Joomla! Documentation Medium 0
Thousands of Online Volunteers High 0
Paid Professional Support Widely Available 0
Total   0

What is the Joomla! Administrator's Security Checklist?

The Security Checklist is a concise selection of the best tips and tricks from the many contributors in the Joomla Security Forums. Review this list BEFORE you install Joomla for the first time.

What are the top 10 stupidest Joomla! security tricks?

A very good question, and sadly one that many did not ask in time. We proudly present the Top 10 Stupidest Administrator Tricks.

How do I choose a quality hosting provider?

The following is a short list of security-related requirements. Depending on your specific needs, you may have many other security requirements such as shell access, cron access, SSL server, etc.

  • Choose *NIX: Joomla! requires at least PHP and MySQL to run. Because Apache/PHP/MySQL run best on UNIX or GNU/LINUX servers, choose a host that offers these options.
  • Use Secure FTP: Choose a host that requires SFTP (Secure FTP) for transferring files. This prevents others from snooping your user name and password from packets as they travel over the Internet.
  • Set PHP register_globals OFF: The most security conscious hosts turn PHP's Register Globals directive OFF by default. The next best allow you to turn it off in local .htaccess or php.ini files. A host that requires you to run a site with Register Globals ON should be avoided. This is true for any PHP enabled site, whether or not you are running Joomla!. There is a legitimate argument to be made by hosts for keeping Register Globals ON for PHP4 sites. This is that it would break too much legacy code. This argument should not be accepted for a PHP5 installation. Beginning with PHP5, the official PHP recommendation was to keep Register Globals is OFF. Note that beginning with PHP6, there will not even be a Register Globals setting, so don't get caught in a Register Globals backwater. Modify your code to work without Register Globals, and choose a host that encourages such practices.
  • Stay up-to-date: Choose a host that stays up-to-date with the latest stable versions of core applications, including the operating system, database, and PHP.
  • Avoid cheap shared servers: Be sure users on your shared server can't view each others files and databases, for example through shell accounts and cpanels.
  • Proactive server management: Choose a host that provides real information about security compromises, rather than simply shutting your site down. Check their user forums for evidence of how they've responded to cracks in the past. A good host may for example, inform you immediately that a security breach has occurred and will quarantine the problem file for you, while leaving it there for further investigation. A poor host will shut your site down and provide very limited information on why. Watch out! All too many do this.
  • Require raw log access: Be sure you have access to raw server logs. Reading these logs is a vital part of site security and recovery.
  • Performance matters: Choose a host that limits the number of users per machine and the average CPU load per machine to some reasonable number (depending on hardware). Be sure they proactively move user sites as needed to balance load. Check the number of domains on a server using reverse IP lookup.
  • Data center: Choose a host that manages it's own data center. Check the data center infrastructure, such as redundant Internet access, hot swappable backups, full daily backups, environment and access controls, emergency generators, etc.
  • Know your neighbors: Check that your host is not at risk of having its IP addresses blocked because it hosts SPAM sites.
  • Visit the Joomla Resources Directory (JRD) hosting section: If you are looking for a Joomla Host, please ensure you make your own investigations as to the services offered and whether they suit your needs or not.
  • Grow with your site: As sites grow in complexity, resource requirements, and security requirements, they may need to be moved off of a shared server environment. At that point, good options include, 1) dedicated servers offer the best possible security and performance, but at the highest expense, 2) virtual servers offer almost all the advantages of a dedicated server, but the hardware and configuration cost is shared among multiple virtual servers.

What are the best practices for site backups?

There are three traditional backup types--full, cumulative and differential.

Full Backups

A complete backup of all associated files and database at a known point in time.
Both of these are considered Incremental backups, they can be used independently of each other or in conjunction with each other but always relate back to a FULL backup.

Cumulative Backups

This is a backup of the differences since the last FULL backup, so each cumulative backup gets bigger each cycle as it is also backing up data previously backup, since the last FULL backup.

Incremental Backups

This is a backup of the changes since the previous backup of any type, i.e., full, cumulative, or incremental.
If you site is not too large, then FULL backups are the way to go, once a week at least. If your content changes quite regularly or more importantly cannot be recreated or is too costly to recreate, once a night or more may be more effective.
If time, server resources, or the rate of data change is too high to successfully obtain a FULL backup every night then the incremental backups are needed.
If you choose to use a cumulative backup following a weekly full, the backups each night will run quicker than a full backup, however as the week progresses, each nightly cumulative backup will increase in size and time, due to not only backing up the changes since last night's backup, but it also backing up all changes each night and previous nights since the last full backup was made. The benefit of this type of backup, in conjunction with full backups is the speed of restoration. To restore, you now only need to recover the most recent full and cumulative backups to fully recover all information.
If time or server resources are paramount or data change overwhelms cumulative backups, turn to differential backups, this style of backup when used in conjunction with a full backup will provide a very similar level of protection, but restoration will be slower. Differential backups will only backup changed data since the last backup of any type, not since the last full backup, as with a cumulative backup. Thus, when restoring data, you will need to recover the full backup, then each differential backup in turn (oldest first) in order to fully recover all information. This method also has the drawback of recovering any legitimately deleted files, potentially "over-filling" the file-system.

Data Protection Best Practice says

  1. You should be able to completely recover from a catastrophic failure from at least two previous full backups. Just in case the most recent full backup is damaged, lost, or corrupt.
  2. A good backup regime should contain at least one full backup within a chosen cycle, normally weekly.
  3. A good backup practice is to store backups away from the current data location, preferably off site.
  4. Dynamic data should be backed up offline or hot to avoid fuzzy backups (data is changing as you back it up, potentially leading to related information not being in sync when backed up.
For the average Web site, a daily or weekly full backup of both site files and database records is normally more than enough. Keeping a number of backups for a period of time is always a good plan, maybe keep each weekly backup for one month. This allows you to recover an old site in the case of emergencies or if for some reason you have local backup file corruption.
There are many PHP and Perl scripts on the Web that can be automated through CRONTAB and can either email (if small enough) or FTP the backup files to an off- or cross- server location. Remember that to some degree with Joomla! you already have an instant backup of the core files, if you haven't modified core, the Joomla! distribution files can be easily restored. Then you need only worry about backing up changed files and the database.

Where can I learn about vulnerable extensions?

Where can I learn more about file permissions?

How do I setup a powerful password scheme?

Overview

Most users may not need more than 3 levels of passwords and webmasters no more than 5. Each level must be completely unrelated to the others in terms of which ids and passwords are used.

Directions

  • Level 5 (Public) - is the password you use on public sites. It is not imperative that you use a different password on every site. In fact it's more effective to use a different username on every site than it is to use a different password truth be told! Knowing the username allows easy hacking...half the work is done! knowing the password is useless unless you know what account it goes to!
  • Level 4 (Webmaster) - Reserved for SQL Only. this is a password that would only be used by SQL and limited to a specific database in SQL. The best way to protect SQL is by limiting each account to just being able to do the minimum that DB requires. In some cases it is even wise to have a read only account for display and a separate write account that the backend write functions use. But that doesn't apply to J! at all... for J! the best practice is to set up an individual account (not root for sure) that only has read and write access to the J! DB nothing else.
  • Level 3 (Webmaster) - FTP and Server Access. these can be the same user:pass combo since both if compromised can do the most damage. doesn't matter if the backend or Cpanel is safe if the FTP is not and the same goes the other way!
  • Level 2 (Personal Data Access) - This password should be used for any sites or locations that contain personal data with the exception of Banking (see level 1). these sites are often used for social engineering data such as medical records, service accounts and any financial records not directly related to banking! You want these to be secure but also different from the real threat of security...your money!
  • Level 1 (Banking!) - this needs to be the most secure in fact if you have two different banks it actually pays to have a different user:pass for each just to be sure!

Joomla! Core

How can I check my Joomla! installation's overall security and health?

1. Use the free Joomla extension, Joomla! Tools Suite (JTS), which is a Joomla! environment audit, maintenance and diagnostic application written in PHP. The JTS suite of tools can diagnose, report and advise on common installation, health and security issues, including performing several common performance and recovery actions.
Project Home: http:// joomlacode. org/gf/project/jts/ (gone away)

How can I add the Joomla! Security Announcements Feed to the Admin Control Panel?

  1. Login to your Joomla! sites Administration site
  2. From the menu, select Extensions -> Module Manager
  3. From within the Module Manager, select Administrator
  4. From the Icon Menu (top right), select New
  5. From the choices available, select Feeds Display
  6. At the Feed Module configuration page, enter the appropriate details (Title (EG: Security Announcements) and Feed as a minimum)
  7. Enter http://feeds.joomla.org/JoomlaSecurityNews in the Feed URL
  8. Select cpanel as the position
  9. Optional Select Apply from the Icon Menu (top right) and place the feed in the order where you want to see it in the Admin Control Panel
  10. Select Save from the Icon Menu (top right)
  11. Go back to your Admin Site main page (Site -> Control Panel) and you should see your newly built Security Feed.
You can also use this technique to deliver your own "Customer Updates" to sites that you build for others. It's a great way to communicate with your customers after handing over the site to them. Every time they log in to the Back End, they'll see your latest news.

Why should I immediately change the name of the default admin user after a new install?

Overview

All new Joomla installations start with a Super Administrator account called, 'admin'. During the installation process, you will be asked to give this account a password. That's great as far as it goes, but because the user name of this highly-confidential account is generally well known, 50% of the security of the username/password combination is already exposed. Now all anyone needs to do is guess the password and they're in.
By changing the user name to something more difficult to guess, you greatly increase the difficulty of accessing the account. An attacker must correctly guess both the user name and password at the same time to gain access. This is several magnitudes more difficult than simply guessing the right password.

Directions

  1. Log into the Back End
  2. Select User Manager
  3. Select the 'admin' user record
  4. Change the value in username. (Good user names contain a mix of letters and numbers.)
  5. Save
  6. Remember the new username!

Why does the Back-End session stay alive even though I set it to expire?

When you edit an item from the Back-End, there is a keep-alive script running that keeps the session active. This is a great convenience in most cases, as it prevents you from losing all your edits if you wait too long to submit the content. However, there are a few potential security issues to be aware of:
  1. If you walk away from your computer while you are editing content, someone else can use your computer to attack the site.
  2. Due to the risk of Cross-Site Request Forgery attacks (CSRF) it's never a good idea to browse the Internet in another window or tab while an open Joomla! Administrator session is active. Joomla! has been hardened against such attacks, but it's remotely possible that an as yet unknown vulnerability exists in the Joomla! core, a third-party extension, or the browser itself.

How do I turn off RG_EMULATION? Joomla 1.0

Overview

PHP's register_globals option was a terrible idea from a security point of view. It encouraged lazy programming and exposed many scripts to needless risk. This is because RG allows variables passed by the user to be automatically passed to the script. This breaks a cardinal rule: Never trust user input.
Register Globals has been officially deprecated in PHP5, and beginning with PHP6 will no longer even exist. Good riddance!
Joomla 1.0.x uses RG_Emulation functions which are somewhat safer than standard PHP register_globals, but it's still best not to allow any form of automatic variable assignments. Note that poorly-written extensions may fail with register_globals turned off. Such failure is a sign that the extension does not check user input correctly. Best advise: Don't use such extensions.

Joomla! 1.0.13

Beginning with the 1.0.13 release, Register Globals Emulation has been moved to the main configuration file and can be adjusting in the Back-end Administrator interface.

Joomla! 1.0.12 and earlier

Edit the file, globals.php, found in the root directory of your Joomla! site. At about line 23 change:
define('RG_EMULATION',1)
to
define('RG_EMULATION',0)

What do Error 1, Error 2, and Error 3 mean?

Error 1 = FATAL ERROR: MySQL not supported...

You need to compile MySQL support into PHP or the MySQL server is down.

Error 2 = FATAL ERROR: Connection to database ...

Joomla! cannot talk to the database, most likly you have a typo in the username or password settings in configuration.php, or you are trying to access a database table with the wrong table prefix.

Error 3 = FATAL ERROR: Database not found...

The database cannot be found. Check the database settings in configuration.php

The MySQL variables in configuration.php (found in Joomla!'s root directory) can be modified to correct these problems.

For Joomla! 1.0.xx

$mosConfig_host = 'localhost';
$mosConfig_user = 'accountname__username';
$mosConfig_password = 'userpassword';
$mosConfig_db = 'accountname_dbName';
$mosConfig_dbprefix = 'jos_';

Modifying the $mosConfig_host to an IP Address of a remote host works for hosts that have separate MySQL servers from the client hosting servers.

How do UNIX file permissions work?

Unix/Linux file permissions can be confusing. The basic UNIX permissions come in three flavors;

Owner Permissions : Control your own access to files.
Group Permissions : Control access for you and anyone in your group.
Other Permissions : Control access for all others.

In Unix, when permissions are configured the server allows you to define different permissions for each of these three categories of users. In a Web server environment permissions are used to control which Web site owners can access which directories and files.

What do Unix permissions look like?

When viewing your files through an FTP client or from the servers command line;

filename.php username usergroup rwx r-x r-x

The first entry is the name of the file, the next entry is your username on the server, the second entry is the group that you are a member of and the last entry is the permissions assigned to that this file (or directory). If you notice, I have intentionally spaced out the permissions section, I have grouped the 9 characters into 3 sets of 3. This separation is key to how the permissions system works. The first set of 3 permissions (rwx) relate to the username seen above, the second set of 3 permissions (r-x) relate to the usergroup seen above and the final set of 3 permissions (r-x) relate to anyone else who is not associated with the username or groupname.

Owner (User) relates to username

The Owner (User) is normally you, these permissions will be enforced on your hosting account name.

Group relates to usergroup

The Group permissions will be enforced on other people that are in the same group as you, within a hosting environment, there is very rarely other people in the same group as you. This protects your files and directories from being made available to anybody else who may also have a hosting account on the same server as you.

Other relates to everyone else

The Other permissions, these will be enforced on anybody else on the server that is either not you or not in your group. So in a Web Serving environment, remembering that no-one else is normally in your group, then this is everybody else accessing the server except for you. Each of the three sets of permissions are defined in the following manner;

r = Read permissions
w = Write permissions
x = Execute permissions
Owner Group Other
r w x r w x r w x

As many of you already know, permissions are normally expressed as a numeric value, something like 755 or 644. so, how does this relate to what we have discussed above? Each character of the permissions are assigned a numeric value, this is assigned in each set of three, so we only need to use three values and reuse them for each set.

Owner Group Other
r w x r w x r w x
4 2 1 4 2 1 4 2 1

Now that we have a value that represents each permission, we can express them in numeric terms. The values are simply added together in the respective sets of 3, which will in turn give us just three numbers that will tell us what permissions are being set. If we are told that a file has the permissions of 777, this would mean that the following was true.

Owner Group Other
r w x r w x r w x
4 2 1 4 2 1 4 2 1

Thus...

  4+2+1 4+2+1 4+2+1
=   7     7     7

The Owner of the file would have full Read, Write and Execute permissions, the group would also have full Read, Write and Execute permissions, and the rest of the world can also Read, Write and Execute the file. The standard, default permissions that get assigned to files and directories by the server are normally;

Files = 644
Directories = 755

These permissions would allow, for files;

644 = rw- r-- r--
Owner has Read and Write
Group has Read only
Other has Read only

and for directories;

755 = rwx r-x r-x
Owner has Read, Write and Execute
Group has Read and Execute only
Other has Read and Execute only


Now, things can get a little complicated when we start talking about shared Web Servers, the Web Server software will be running with its own username and groupname, most servers are configured for them to use either "apache" and "apache" or "nobody" and "nobody" as username and groupname. Here is the problem. Your Web Server runs as its own user, and this user is not you or in your group, so the first two sets of permissions do not apply to it. Only the world (other) permissions apply. Therefore, if you configure a permissions set similar to 640 on your website files, your Web Server will not be able to run your website files.

640 = rw- r-- ---
Owner has Read and Write
Group has Read only
Other has no rights

The Web server is assigned no permissions at all and cannot Execute, Write or more importantly, even Read the file to delivery its content to a website visitors browser. If a directory was to be assigned 750 permissions, this would have the same effect, because the WebServer does not even have permissions to read files in the directory, even if the files inside that directory had favorable permissions.

750 = rw- r-x ---
Owner has Read and Write
Group has Read and Execute
Other has no rights

Directories have an extra quirk, if a directory does not have the Execute permission set in the World set then even if Read and Write are set, if the program is not run as the user or group, it will still not be able to access the files within the directory. The Execute setting allows the program to "Execute" commands in the directory, so without it being on the program(in our case a Web Server) cannot execute the "Read" command, thus cannot deliver your file to the users web browser.

How Does this Relate to Joomla?

Good question, well in the first instance this would be important during the Web-Installer process. If you can remember back to when you ran the Joomla! Web-Installer, we were looking for specific directories to be designated as writable. We see quite a numbers of posts either stating that there were problems during the install with permissions or asking what permissions are recommended. Some even consider the message, asking for "Writable" permissions to be too vague.

Unfortunately, as the Web-Installer does not know how your server is configured, then it cannot be more specific, however, once you understand the permissions settings and you know a little about Web Serving environments, you will actually find that the term writable is actually very specific and a more than adequate description of what Joomla! needs. Thinking back to the above information, you may remember that there are three places where write permissions maybe set;

Owner Writable
Group Writable
Other Writable

Also remembering that the Web Server generally doesn't run as your own user or in the same group. When you run the Web Installer from a browser, it is the Web Server trying to access the files, thus it is the "Other" permissions that will apply to it. If the "Other" permissions do not allow the Web Server to Read, Write or Execute commands in the Joomla! directories, you will receive the message saying that the directories are not writable.

In this case, you will need to configure the Other permissions to be "7" on the directories listed in the Web Installer. So your total permissions might be something like 757, in the worse case you might need to set 777. These very open permissions maybe reset back to 755 after the installer runs to assist in the security of your directories and files.

757 = rwx r-x rwx
Owner has Read, Write and Execute
Group has Read and Execute
Other has Read, Write and Execute

Just to make things even more confusing, many hosting firms make use of software called phpsuExec or suExec, these tools change the way the Web Server runs, where the Web Server would not normally run as your username, in this case, it does. The use of the other permissions, may not be required, now you may only need to configure directories to be writable to your own username and groupname, this allows directory permissions to be set as 755 or 775 instead of 757 or 777.

755 = rwx r-x r-x
Owner has Read, Write and Execute
Group has Read and Execute
Other has Read and Execute
775 = rwx rwx r-x 
Owner has Read, Write and Execute
Group has Read, Write and Execute
Other has Read and Execute

The Web Server will still need to Execute set for the username and Read, Execute groupname permissions set so that it can Execute the Read command on files inside the directory. Again, these permissions may be demoted back to 755 after the Web Installer completes. Thats the basics for directories covered, what about files? This is where things get a little simpler. Most of the files that Joomla! makes use of will be quite happy with the 644 default permissions.

644 = rw- r-- r-- 
Owner has Read, Write
Group has Read
Other has Read

This is valid if you do not have a need to Write to the files from the Web Server, the same rules apply as for directories if you do have this need. One file that you may like to have "Writable" to the Web Server is your configuration.php file. This is the Joomla! configuration file, if you plan on changing configuration through the Web Admin interface, then this file will need to be Writable to the Web Server.

If your server needed directory permissions to be set to "Other" Writable for the install then this file will probably also need to be 757 or 777. Leaving this file as 757 or 777 is dangerous though, as you are letting everyone have "Write" access, many Web Site exploits take advantage of this fact, so in general it is not recommended to leave this file with these permissions.

If your Web Server has one of the SU tools installed and you only needed to configure 755 on directories for the installation, then you will probably also only need to set 755 or 775 on this file to allow editing through the Admin interface, and these permissions are generally accepted as more secure than 757 or 777.

In conclusion, what permissions should be set for the Joomla! installation? Well, as you can see, it depends!

I know this isn't as helpful as you would have liked and it certainly is not a definitive answer, but in general, after the installation, any insecure "7" settings can be reset back to something more secure. For example:

Files = 644
Directories = 755

These permissions would allow, for files;

644 = rw- r-- r--
Owner has Read and Write
Group has Read only
Other has Read only

and for directories,

755 = rwx r-x r-x 
Owner has Read, Write and Execute
Group has Read and Execute only
Other has Read and Execute only


If you have SSH shell access the following commands can be run from the command line to reset all files and directories back to the server defaults of 755 and 644. Change directories to the top directory (" / ") of your Joomla! installation, then run:

find . -type f -exec chmod 644 {} \;
find . -type d -exec chmod 755 {} \;

If you only have FTP access, this can be a very time consuming job, however, unless you changed more directories during the installation that was requested, you should only need to reset about 10 directories and the configuration.php file.

Keep in mind that to install any extensions or templates after the actual Joomla! installation you may need to elevate the default permissions again on the appropriate directories just for the installation period, you may then demote them again after the add-on is installed.

If you decide to use caching the cache directory will need to be writable by the Web server user to allow it to write its temporary files.

What are the recommended file and directory permissions?

Depending on the security configuration of your Web server the recommended default permissions of 755 for directories and 644 for files should be reasonably secure.

How can I avoid using chmod 0777 to enable installs?

On a private server with a small, controlled set of users, there is no need to use a chmod 777 to make the Joomla! folders writable in order to perform installs. You can set the server up so that both Apache and FTP have control of site files.

Directions

  1. Edit the Apache user.conf file and tell apache to run under the FTP account.
  2. chmod the entire site to 644 or 744. Apache should be able to run just fine that way.

Optional

  1. chgrp the entire web space to the FTP group so that only those with FTP access can write to the server.
  2. chmod the entire web space to 764 or 664 will be possible giving other users write access as well

Isn't locating all Joomla! files inside public_html a security risk?

Short answer

Potentially, yes. Your site can be secure, but you must be careful and vigilant.

Long answer

A common security principle is to create various security levels and then grant access at each level only as required. On UNIX servers this is done by setting the user, group, and world permissions on directories and files.

Typically, the most insecure directory on a UNIX server is the one serving Web files, usually called public_html. This is because it is publicly accessible, world-readable, and in the case of a CMS-powered site, possibly even world-writable. That status is the very definition of officially, totally, and utterly insecure.

As long as you want the entire world to view your public_html directory there is no problem. After all, that's exactly what it's designed to do. But if you want to hide anything, the plot thickens. If public_html contains configuration files with secret data, or scripts that write to databases, or scripts that modify other files, or scripts that append to logs, or scripts that store temporary data in caches, or scripts that support file and graphic uploads, or scripts that process form input, or scripts that process financial and personal data, this read-only directory becomes a world-accessible, read-write application.

If there are ANY vulnerabilities in ANY files in the public_html directory, the entire server is potentially vulnerable, and not just your Web site but possibly every Web site on your server. Such vulnerabilities give attackers access to the scripting engines used to run your site. PHP, Perl and other Web scripting languages are powerful and easy to use. If programming vulnerabilities allow an attacker to call arbitrary commands, your entire server could be toast.

One good way to block attackers, is to keep potential vulnerabilities behind a secure fence. For this reason, it is often recommended to only place files that require direct access from the Web in public_html. Other files should be loaded into applications using such functions as include and require. To access such files, attackers must first penetrate your server, such as by discovering a root username/password.

The incredible lightness of living outside the fence

To provide incredibly easy installation, Joomla! follows a different security model. It is possible to perform a complete Joomla! installation using nothing more than a Web browser pointed at the world-readable installation directory. An additional level of security is provided by requiring that you remove this installation directory after completing the install.

Granting a world-accessible installer the ability to write to files outside of public_html would be a huge security hole. Thus, by default every Joomla! file ends up in the world-accessible public_html directory. Not coincidentally, this is also the directory in which an angry planetful of would-be attackers are hoping to find your files.

Currently, most Joomla extensions also have limited support for file locations outside of public_html. This is a legacy of the Joomla! 1.0.x installation model.

Joomla! defense

Despite it's apparently vulnerable location, Joomla! uses various effective methods for blocking exploits. Chief among them is to add a line of code at the top of any PHP file that requires extra protection. This method is very effective as long as each and every file requiring such protection, has it. One vulnerable file exposes the whole site.

The challenge

The practice of placing everything in public_html, and then building a little fence inside each file can become an administrative nightmare. One vulnerable file exposes the entire server. This is a glaring example of an allow, then deny security model.

This model requires very careful upgrades, constant log reviews, and proactive plugging of new vulnerabilities as soon as they become known. (Since you have to beat the attackers, you'll be in a hurry, and may inadvertently do something stupid, potentially creating other vulnerabilities.)

During installations and upgrades, you must verify (or trust someone else to verify) every line of code, of every new file, for every known vulnerability. And because scripts can have unintended consequences on each other, you cannot forget to test, test, test. Of course this is generally true for all software, but placing the entire application in public_html makes the issue extremely critical.

The recent wave of URL injection attacks against poorly-written third party extensions would have been much less successful if those files had been stored outside of public_html, and thus simply unavailable through URLs. Note that in many cases the actual vulnerabilities could still exist within the files, but being inside the fence (outside of public_html) they would not be exposed to URL injections.

To (Deny, then Allow), or (Allow, then Deny)?

The real problem with the above "all known" qualifier is that it is an allow, then deny model. In other words, we first give everyone access to every file and then deny access to specific files by adding a line of code.

Consider the logic for a password authentication script. We have essentially two choices:

  1. First allow all access, then deny any username/password combination that DOES NOT match the approved list.
  2. First deny all access, then allow any username/password combination that DOES match the approved list.

Obviously the second method is better. A passing familiarity with regular expressions shows that the first method is much more difficult to write securely. It fails anew each time a new variation of some attack is developed, and tends to require constant revisions. Over time, such revisions become so complex that the authentication system itself becomes a source of vulnerabilities.

Conceptually, the second method is an example of building a strong fence around your site (deny), and then granting access using a limited and well-defined set of criteria (then allow). If the script fails, the most likely result is that someone who should have access is blocked. That may be highly inconvenient, but it's not usually a security breach.

The good news

  1. In Joomla! 1.0.x, some extensions, and the Joomla! framework, give you the option of locating critical directories outside of public_html after you have completed the installation. Whenever possible you should do this.
  2. Joomla! 1.5 goes far in the right direction. It provides several new constants for specifying the location of particularly sensitive directories, including configuration, administrator, libraries, and installation.
  3. Joomla! 1.5 is able to run as an FTP account. This provides another method for protecting files on a file by file and directory by directory basis.

How do I adjust Joomla 1.5 defines Joomla 1.5

There are two defines files that will generally need to be edited. /includes/defines.php file is for the front end and /administrator/includes/defines.php is for the Joomla administrator end. Below is the relevant code.

define( 'JPATH_ROOT' , implode( DS, $parts ) );
define( 'JPATH_SITE' , JPATH_ROOT );
define( 'JPATH_CONFIGURATION', JPATH_ROOT );
define( 'JPATH_ADMINISTRATOR', JPATH_ROOT . DS . 'administrator' );
define( 'JPATH_LIBRARIES' , JPATH_ROOT . DS . 'libraries' );
define( 'JPATH_INSTALLATION' , JPATH_ROOT . DS . 'installation' );

.DS. = Directory Seperator

Moving sensitive files outside the web root

Moving sensitive files is now documented at: http://docs.joomla.org/Moving_sensitive_files_outside_the_web_root

How do I block direct access to critical files using .htaccess?

  1. Make a backup copy of your .htaccess file. Use your backup file to recover if the following fails. Be sure to delete the backup file once you are finished.
  2. Add the following to your .htaccess file. This example will protect both the configurtation.php and .htaccess files.
<Files .htaccess>
order allow,deny
deny from all
</Files>
<FilesMatch "configuration.php">
Order allow,deny
Deny from all
</FilesMatch>

You can also protect a lot of file extensions in one single rule. Exemple (the file names between ' ( ' and ' ) ' in this rule are the file extensions to protect ):

<FilesMatch "\.(htaccess|htpasswd|ini|phps|log|sh|conf)$">
Order allow,deny
Deny from all
</FilesMatch>

How do I recursively adjust file and directory permissions?

Using Joomla! Administration

In the Back-end, go to Site --> Global Configuration --> Server.

Using the UNIX shell

Note: The find command automatically assumes that it should start from the current directory. To be safe, go to your public_html directory and specify a path as the first argument. Some shells, such as bash on Apple OS X, must have a path specified in the find command.

find . -type f -exec chmod 644 {} \;
find . -type d -exec chmod 755 {} \;
chmod 707 images
chmod 707 images/stories
chown apache:apache cache


Notes:

  1. Test all third party extensions after changing permissions.
  2. You may need to reset write permissions to install more extensions.

How can I set the administrator directory to use an SSL server (https)? Joomla 1.0

Use Joomla version 1.5 or newer

A standard Joomla! 1.0.x installation does not support SSL for individual directories, however there are various (elegant and not so elegant) hacks posted in the forums.

Note that earlier techniques involving the variable $mosConfig_live_site are deprecated, and will not work with current Joomla! versions due to increased security enhancements.

More Help

  1. Netshine Software, Ltd: Using an SSL Certificate with your Joomla Website

Why isn't restricting access by IP recommended?

Restricting site access by IP address is not particularly effective longterm as many exploits are enacted from hijacked machines or via proxies, masking the real attacker's actual IP Address. Attackers can attack from many different compromised machines. Blocking them will block the legitimate owners of that IP, but may not block the attackers.

Joomla! Extensions

Why are there vulnerable extensions?

A list of currently known vulnerable extensions.

Anyone may write and distribute a Joomla! extension. As a service to the global community, this freedom is actively encouraged and supported by the Joomla! Core team. Due to the openness and popularity of the Joomla! project, there are a wide variety of extensions offering a vast array of features. The quality and breadth of Joomla! extensions is one of the main advantages of Joomla.
However this freedom comes with a price. It requires individual responsibility, and can survive only where a majority of participants act responsibly. Joomla's success has led to unwanted attention from malicious types, such as script kiddies who run simple, automated scripts in an effort to find and deface others' Web sites.
It is important to note that, script kiddies unintentionally perform a valuable service. They help us identify vulnerable extensions and poorly configured servers that might otherwise remain open to more serious threats.

What is a vulnerable extension?

A vulnerable extension is one that has been found to contain (or contribute to) a security vulnerability.

Vulnerable extensions are not necessarily poorly-coded. As the Web evolves, technical requirements and commonly accepted coding practices change. Active projects release new versions of their extensions as requirements change. For this reason, it is important to:

  1. Know the version numbers of all installed extensions.
  2. Use only the latest stable version of all extensions.
  3. Completely remove all files of insecure or unused extensions.

How do I choose secure extensions?

The most important thing anyone can do is make good decisions regarding the extensions they choose to use on a site. Once an insecure or malicious extension is installed you should consider your entire site compromised. There is NO POSSIBLE WAY to protect or stop a component from accessing database tables it should not be accessing. There is no possible way to stop a component from sending all of the information it found back to a cracker website. Once an insecure or malicious component is installed, your entire site is insecure.
With all of that said, here are some pretty easy tips for making good choices regarding the extensions you install:

1. When was the last version released?

If it has been over a year, consider the project abandoned and find something else. Do not install old components.

2. What kind of release is it? (Stable, Release Candidate (RC), Beta, Alpha)

For production sites you should be sticking to Stable releases as much as possible. If you cannot wait until a Stable release has been made available, Release Candidates are the only other option you should consider. I would not suggest anyone install any Beta or Alpha extensions on a production site. This means they still have bugs, they have not been tested enough, and could have any number of inconvenient bugs or security issues that have not been fixed or worse, found.

3. Does the extension have a history of good security practices?

This is obviously a bit more subjective but it is still a very valid gauge of future trustworthiness. It requires a bit of investigation and research. Look around their download pages and archives, are there many security release or patches? Are there a lot of reports of cracking activity through this extension? Are the developers experienced and security conscious? What do other community members think of this extension? One example that comes to mind that has little to do with Joomla itself (which makes it a fair example) is phpBB. This script has had more security issues than I could get my head around and there routinely seems to be newly disclosed issues. Because of this, I would never use phpBB. In my opinion its is not trustworthy and there is a high probability that there will be more major security issues.

4. Is there a support community for this extension?

This is very important for usability and security awareness. If there is a support community for an extension there is a better chance of security issues being known and dealt with. A support community means that people would like to continue using the extension and that they care about the extension. This furthers the chance that security issues will be found, disclosed, and dealt with promptly.

5. Is there only a Mambo version of this extension?

While this does not in itself make an extension insecure but is rather a gauge of support, how recently the last realease was, and future support. There is a pretty narrow chance that Mambo components will be supported in 1.5 so save yourself the trouble and find a component made to work with Joomla. It will make your life easier.

6. Is the extension generally bug free?

I hinted on this a little bit in number three but I think it is worth discussing in more depth. While it is almost impossible for an extension to be completely bug free, the smaller the number of bugs, the better. If there are bugs in the software it means there are mistakes in the software. The more mistakes, the higher risk of usability issues and security issues. Security issues are often a result of not one bug, but several bugs or bad practices. For example, the recent 3rd party vulnerabilities that allow for remote file inclusion are a result of:

Bad Practices:

  1. Having PHP's Register Globals enabled.
  2. Using out of date or abandoned extension.
  3. No other security checks enabled for PHP. (url_fopen off, open_basedir restrictions, disabled PHP functions)
  4. Poorly configured file permissions.
  5. No request filtering or software "firewall". (such as mod_rewrite rules or mod_security Apache modules)

Bugs:

  1. Not including defined('_VALID_MOS') or die... statements
  2. Poorly constructed include() statements.

Although the Joomla! core is secure when configured correctly, third party extensions come in all flavors of age and quality. Unless you absolutely trust the extension developer, always review the code should before installing. The following is a list of typical areas of concern.

1. How complex is the extension?

The larger it is, the more likely it is to have problems, and the more carefully you should review it. If you can't tell what it's doing, you should not trust it.

2. Does the extension read or write files to your server?

Programs that read files may inadvertently violate access restrictions you've set up, or pass sensitive system information to crackers. Programs that write files have the potential to modify or damage existing files, or introduce trojan horses.

3. Does the extension interact with other programs on your system?

For example, many extensions send e-mail in response to a form input by opening a connection with the sendmail program. Is it doing this in a safe way?

4. Does the extension run with suid (set-user-id) privileges?

In general this is very dangerous; extensions need an excellent reasons for doing this.

5. Does the extension validate all user input, such as in form fields and in the URL?

6. Does the extension use explicit path names when invoking external programs?

Relying on the PATH environment variable to resolve partial path names is a dangerous practice.

7. Is the extension secure against direct access throught the URL?

For example: www.yoursite.com/components/com_bad_extension.php?lots_of_bad_code_here

8. Is the extension secure against remote file inclusions?

9. Is the extension secure against SQL injections?

10. Is the extension secure against Cross Site Scripting (XSS)?

11. Does the extension need PHP register_globals ON, or Joomla! RG Emulation ON?

If so, then it is probably violating number 7 above.

12. Does the extension provide higher database access to less privileged users?

For example does it allow guests or registered users to view data that only publishers or administrators should be able to see?

Why does the Extensions site include insecure extensions?

Overview

The Joomla! Extensions site exists as a free service to the community. Anyone can post extensions there and extensions exist at all levels of quality and maturity.

If an extension is found to contain vulnerabilities, it will be removed from the site until a safer version is released, but there is no guarantee that the vulnerabilities of every extension have been discovered or reported.

To be safe, you must verify the security of every extension you install.

Below is the text of the Joomla! Extensions site disclaimer. Ignore it at your peril.

Disclaimer

The extensions and reviews listed in this area have been submitted by the community and their listing does not constitute or imply endorsement, recommendation, or favouring by Joomla!/OSM.


This content is provided as a free service to our visitors, and, as such, Joomla!/OSM cannot be held liable for the accuracy of the information. Visitors wishing to verify that the information is correct should contact the parties responsible for authoring the content and/or development of the extension.

Why is there a warning in the extensions install screen?

It's just a warning! You are of course free to install any extension you want onto your own site, but remember that YOU are responsible for the safety of your site and the quality of the applications you install.

The vast majority of reported Joomla! vulnerabilities are through poorly-written or obsolete versions of third party extensions that should not have been left on the server. Therefore, before installing anything carefully evaluate the quality of the extension's code.

The Vulnerable Extensions List is a valuable source of information on what NOT to install.

Why isn't un-publishing a vulnerable extension enough to protect my site?

Overview

Simply removing the menu links to an extension, or unpublishing a module is NOT enough to protect your site! As long as the extension's files exist on your server, you are vulnerable. Note how in the following examples an attacker can bypass the Joomla! index file to directly target any file, of any extension.
www.your_site.org/components/com_bad_component/vulnerable_file.php
www.your_site.org/modules/mod_bad_module/vulnerable_file.php

Directions for removing a vulnerable extension

1. Make a list of files to remove

If you can locate it, read the extension's xml file to determine exactly which directories, files, and database tables were added to your system. The xml file is in the original zip archive used during the extension install process. For example, the zip archive for an extension called mod_vulnerable, would contain an xml file called, mod_vulnerable.xml, and might contain a list of files such as the following:
mod_vulnerable.php
mod_vulnerable/vulnerable_file.txt
mod_vulnerable/another_vulnerable_file.txt
mod_vulnerable/yet_another_vulnerable_file.txt
mod_vulnerable/index.html

2. Uninstall via the Joomla Installer:

Using the Installer in the Joomla! Administrator backend, uninstall the vulnerable extension. You may also need to uninstall related modules, components, or plugins.

3. Check that the uninstall process was complete:

Don't trust the extension to safely remove all of it's files. Compare directories and files on your system to the extension's xml list to ensure that all related files were actually removed.

4. Optionally, remove related database tables:

Check your database and remove any tables created by the extension. To ease the upgrade process to new versions, many uninstall scripts do not remove related database tables. You can find the list of tables in each extension's xml file. (If you plan on installing a safer, compatible version of the same extension and you want to reuse existing data, you can usually leave the database tables as they are.)

Apache

Covers information on Apache Web server, Apache modules, .htaccess files, etc.


What is Apache modSecurity?

Overview

ModSecurity is an Apache module that functions as an embeddable web application firewall. It provides protection from a range of attacks against web applications and allows for HTTP traffic monitoring and real-time analysis with no changes to existing infrastructure. It is also an open source project that aims to make web application firewall technology available to everyone.

When configuring ModSecurity, it is important to know that it is not only the Joomla! application that may require unique rules, but also the data that the application processes.

Quality hosting providers customize mod_security rules to suit each customer.

If you have a conflict between Joomla and ModSecurity, it is often third party components, and sometimes even contact form submissions that trigger the problem. Joomla out of the box usually works with typical ModSecurity settings, but this is dependent on each hosting provider's unique configuration.

Overall, mod_security is a excellent tool, but this is really something your host should manage.

One specific error is the failure of file uploads, this is often caused by SecFilterScanPOST being enabled. If you get an internal server error while using the flash upload in the Media Manager this is a good place to start. You can disable this setting by adding SecFilterScanPOST Off to your .htaccess file.

ModSecurity configurations are far too varied and complex to describe here. To learn more, see the following resources:


Resources

  1. Official ModSecurity Site
  2. ModSecurity and Apache

How do I block directory scans using .htaccess?

Directions

Add one of the following Apache rewrite rules to your .htaccess file. The first example will internally rewrite all attempts to access files with names starting with "phpMyAdmin" to index.php. Be wary of using this as it allows a seemingly valid duplicate URL for your homepage. The second rule is more safe. It simply returns a 403 response.


Sample Apache Rewrite Rule

RewriteRule ^phpMyAdmin /index.php [L]
RewriteRule ^phpMyAdmin - [F]


Some Regular Expression Tips

^ Means start of pattern
. Means any character other than newlines
+ Means one or more of the previous character
* Means zero or more of the previous character
$ Means end of pattern
\.  Literal periods must be escaped with a leading \

How can I change PHP settings using .htaccess?

Introduction

This FAQ explains how to set boolean PHP configuration directives using php_flag. The format for php_flag is: php_flag name on|off


Directions

1. Open the .htaccess file located in your site's home directory, or if you don't have one, create a blank one now. Note the period character (.) at the beginning of the file name.

2. Add any of the following code samples to your .htaccess file, each on it's own line. These sample commands will prevent common global variable injection attacks, cross site scripting (XSS) sttacks, and code injection attacks.

php_flag register_globals off
php_flag allow_url_fopen off
php_flag magic_quotes_gpc on


Note that although the magic_quotes_gpc directive adds a layer of security, for performance reasons it is not considered a best practice. If you have verified that your site correctly filters and validates all user data (and every production site really should), then there is no need to add this directive. If you have any doubt, add it.

3. Save the .htaccess file in your site's home directory.

4. Test your site's front end and back end.

How does FastCGI effect Joomla?

When PHP runs from FastCGI, your server runs the PHP interpreter like an Apache module, but with the rights of your user account. Usually, the PHP interpreter is either running as the user of the webserver (which is fast, but insecure, since everyone's scripts run with the same rights), or as a CGI program, which is slow. Thus, FastCGI is a good solution for shared hosting.

Since the PHP interpreter runs as a single instance, it does (AFAIK) not parse the .htaccess or php.ini files per directory. To change php.ini settings, your host must offer you a method to set up or modify your own php.ini, or at least parts of it. Here is how one of host does this: it parses one php.ini file (which the user can modify) once an hour, and puts some well-defined settings into the web server's main php.ini file. Thus, users are able to change some settings for their site only, such as turning register_globals off, switching between PHP4 and PHP5.

If your server uses FastCGI, you can ask them to enable a method such as the above example, or you may be able to ask them adjust some settings for you.

How can I check if mod_rewrite is enabled?

Many problems with search engine optimization (SEO) arise from the fact that a host has not enabled mod_rewrite on the server.

1. Enable SEO in your administrator! (administrator > SEO > Enable > Save)

2. Rename your htaccess.txt to .htaccess, or use your existing .htaccess file.

3. Place ONLY the following lines in your .htaccess file in the domain root folder.

      Options +FollowSymLinks
      RewriteEngine On
      RewriteRule ^joomla\.html http://www.joomla.org/ [R=301,L]

4. Point your browser to: http://www.example.com/joomla.html

(Replace 'example.com' with your site's actual URL.)

5. If you are redirected to www.joomla.org, mod_rewrite is working. If you get an error, mod_rewrite is not working.

6. Note: if your site is located in a folder, for example "test" you will need to modify the .htaccess file as follows:

      Options +FollowSymLinks
      RewriteEngine On
      RewriteRule ^test/joomla\.html http://www.joomla.org/ [R=301,L]

How do I switch to PHP5 using .htaccess?

Overview

Many shared server environments currently run .php scripts using the PHP4 interpreter and .php5 code using the PHP5 interpreter. Rather than changing all your file extensions, and perhaps breaking many links, use a .htaccess file to dynamically map one extension to the other.

IMPORTANT CAVEAT: One common reason for doing this is that hosts leave PHP4 configured with register_globals ON in order to support legacy code while offering PHP5 with register_globals OFF. If you are on a shared server at a host that has configured register_globals ON server wide, you should be very worried!

Turning register globals OFF via a local php.ini or a .htaccess file will NOT offer you any extra protection. Another exploited account on your server can simple hack yours. For server security, and since php 4.2, register globals is OFF server wide by default (php default). Any host overriding this is inviting trouble. If you need register globals ON for a specific site, simple use a .htaccess file for that specific directory, and server wide security will not be compromised. Of course, if you do this be sure all effected scripts fully sanitize input data.

Requirements

1. Your Apache server must be configured to use .htaccess files. If not, you may be able to request this from your host. 2. Your Apache configuration must allow the following setting. If not, you may be able to request this from your host. 3. Your host must have configured the .php and .php5 file extensions as described above. If not, they may possibly have chosen other extensions. Check with your host.

Directions

1. Check to be sure your site is configured to use .htaccess files.

2. Make a backup of the .htaccess file in your root public_http directory. If you don't have a .htaccess file at this location, create one now.

3. There are various ways to set the comman, depending on your server configuration. One of the following will probably work. Add ONE the following lines at the end of your .htaccess file. If unsure which to use, check with your hosting provider on which version works best for your configuration.

AddType x-mapp-php5 .php
AddHandler application/x-httpd-php5 .php
AddHandler cgi-php5 .php

4. Carefully test.

5. Delete the backup .htaccess file. Don't leave backups of .htaccess files in public directories.

How do I password protect directories using .htaccess?

Overview

This FAQ explains how to protect the Joomla! /administrator/ directory on Apache servers using the htpasswd utility. You can easily adapt these instructions to protect other directories. If you need help finding or creating your .htaccess file, start here.

Caveat (From Apache.org)

Basic authentication should not be considered secure for any particularly rigorous definition of secure. Although the password is stored on the server in encrypted format, it is passed from the client to the server in plain text across the network. Anyone listening with any variety of packet sniffer will be able to read the username and password in the clear as it goes across.

Not only that, but remember that the username and password are passed with every request, not just when the user first types them in. So the packet sniffer need not be listening at a particularly strategic time, but just for long enough to see any single request come across the wire.

And, in addition to that, the content itself is also going across the network in the clear, and so if the web site contains sensitive information, the same packet sniffer would have access to that information as it went past, even if the username and password were not used to gain direct access to the web site.

Don't use basic authentication for anything that requires real security. It is a detriment for most users, since very few people will take the trouble, or have the necessary software and/or equipment, to find out passwords. However, if someone had a desire to get in, it would take very little for them to do so.

Basic authentication across an SSL connection, however, will be secure, since everything is going to be encrypted, including the username and password.

Directions

1. If you are unfamiliar with the Apache htpasswd utility, you may want to read the following link first. Apache Authentication, Authorization, and Access Control

2. Check to be sure your site is configured to use .htaccess files. If not sure, ask your host.

3. Decide where to put your .htaccess file. Because Apache recursively searches all directories in a path for .htaccess files, the higher in your directory structure you place this file, the more directories it will control. If there is already an .htaccess file in the directory you choose, it's probably best to add the new code to it.

4. Decide where to store your.htpasswd and .htgroups files. These files should NEVER be publicly accessable through the Web. Below is an example directory structure showing good locations for each file. Note that the /auth/ directory in this example is NOT accessible from the Web.

/home/mysite/public_html/.htaccess
/home/mysite/auth/.htpasswd/
/home/mysite/auth/.htgroups/


5. Create the .htpasswd and .htgroups files as explained in the official Apache HowTo, referenced above. (Since you've read the always current and official documentation at Apache.org, we'll spare you the trouble of displaying it again here.)

6. If a .htaccess file already exists in the directory you have chosen, make a backup copy. If the file does not exist, create a new file with that name now. (Don't forget the dot at the beginning of the name.)

7. Add the following code to the .htaccess file. Adjust the example paths (marked in red) as needed for your server. Adjust the group name that you created in step 5 if it differs from the below example.

AuthUserFile /home/auth/.htpasswd
AuthGroupFile /home/auth/.htgroups
AuthType Basic
AuthName "LWS"
require group admins

8. Test carefully.

9. Remove all backup .htaccess files from public_http directories.

10. If you cannot use the Apache htpasswd utility, here's a free, online script that creates the necessary files for you. You'll need to know the user name, password, and path. The script does the rest for you. Note that for more advanced configuration, such as the use of groups, you'll need to edit the resulting files.

.htaccess Generator: http://www.webmaster-toolkit.com/htaccess-generator.shtml

How do I restrict directory access by IP address using .htaccess?

Overview

This can be a very effective way to protect your Joomla! administrator directory. Any other directory in public_html can be protected in the same way. This method only works if you have a static IP address assigned to you. Anyone attempting to browse such directories using a different IP Address will get a 403 Forbidden error.

Directions

  1. In the directory you wish to protect, open (or create) a file called, .htaccess. (Note the dot at the beginning of the file name.)
  2. Add the following code to this file, replacing 100.100.100.100 in this example with the static IP address you plan to allow:
Order Deny,Allow
Deny from all
Allow from 100.100.100.100


  • Optional: You can enter partial IP Addresses, such as, 100.100.100. This allows access to a range of addresses.
  • Optional: You can add multiple addresses by separating them with comma's.
100.100.100.101, 100.100.100.102

How do I convert an htaccess.txt file into a .htaccess file?

Introduction

When using PHP as an Apache module, you can change the configuration settings using directives in Apache configuration files (e.g. httpd.conf and .htaccess files). You will need "AllowOverride Options" or "AllowOverride All" privileges to do so. If you control your own Apache configuration, you can and should use httpd.conf. If you do not control your Apache configuration (such as on a shared server), you must use .htaccess files.

Directions

  1. First look for the file, htaccess.txt in your root directory. It should have been installed during the Joomla! installation. (Note that this file name does not begin with a dot.) Open and carefully read htaccess.txt. It contains important suggestions on how to protect your site.
  2. Make any adjustments to this file as appropriate for your site, and then save it in your site's home directory as, .htaccess (including the dot).
  3. Test your site's front end and back end. If it produces errors, rename the file back to htaccess.txt, and troubleshoot your edits. If you are unable to get this working, you may have to leave the file named htaccess.txt.
  4. Use phpinfo() to ensure that all configurations set as you intended. Note: Web-accessible files that include phpinfo() are potential security risks they offer attackers lots of useful information about your server. Always remove such files after use.


More Information

How do I block direct hot linking to image files using .htaccess?

Caveats

  1. Your server must allow .htaccess files for this technique to work.
  2. If you do not have a .htaccess file in your root directory, see the related FAQ first.
  3. Do not use this method to redirect image hot links to HTML pages or to servers that are not your own.
  4. Hot linked images can only be replaced by other images, not with HTML pages.
  5. As with any .htaccess rewrite, you may block legitimate traffic, such as users behind proxies or firewalls.

Directions

  1. Create a jpeg image called no_hot_link.jpe. Note that the odd file extention (.jpe) is intentional and important. Place this file in your images directory.
  2. Place the following code in the .htaccess file of your root directory.
 RewriteEngine On
 RewriteCond %{HTTP_REFERER} !^http://([^.]+\.)*your_site\.com/ [NC]
 RewriteCond %{HTTP_REFERER} !^$
 RewriteRule \.(jpe?g|gif|bmp|png)$ /images/no_hot_link.jpe [L]

Explanation

The first line begins the Apache rewrite rule. The second line matches any requests from your own site, here called your_site.com url. The [NC] flag means "aNy Case", which means, match any and all upper and lower case characters. The third line allows empty referrals such as when a user is behind a caching proxy. The last line matches any files ending with the extension jpeg, jpg, gif, bmp, or png. This is then replaced by the no_hot_link.jpe file in your images directory. This JPEG file uses the extension jpe instead of jpg to prevent these rules from blocking your replacement image.

Block hot linking from specific domains

To stop hotlinking from specific domains only, such as myspace.com, blogspot.com and livejournal.com, while allowing other web sites to hotlink to your images, use the following code:

 RewriteEngine On
 RewriteCond %{HTTP_REFERER} ^http://([^.]+\.)*myspace\.com/ [NC,OR]
 RewriteCond %{HTTP_REFERER} ^http://([^.]+\.)*blogspot\.com/ [NC,OR]
 RewriteCond %{HTTP_REFERER} ^http://([^.]+\.)*livejournal\.com/ [NC]
 RewriteRule \.(jpe?g|gif|bmp|png)$ /images/nohotlink.jpe [L]

You can add as many different domains as you want. Every RewriteCond line except the last one should end with the [NC,OR] flags. NC means to ignore case. OR means "Or Next", as in, match this line OR the next line. The last RewriteCond omits the OR flag to stop matching after the last RewriteCond.

Display a 403 forbidden code

Alternatively, you can display a 403 Forbidden error code. Replace the last line of the previous examples with this line:

RewriteRule \.(jpe?g|gif|bmp|png)$ - [F]

PHP

Why is Joomla! written in PHP?

Might as well get it from the horse's mouth. In Do you PHP?, Rasmus Lerdorf, the originator of PHP, sums up how and why PHP developed as it did.
"What it all boils down to is that PHP was never meant to win any beauty contests. It wasn't designed to introduce any new revolutionary programming paradigms. It was designed to solve a single problem: the Web problem. That problem can get quite ugly, and sometimes you need an ugly tool to solve your ugly problem. Although a pretty tool may, in fact, be able to solve the problem as well, chances are that an ugly PHP solution can be implemented much quicker and with many fewer resources. That generally sums up PHP's stubborness."

What is the latest stable release of PHP?

Check the official PHP download page for information on the latest PHP release.

How do I tune for speed with PHP5 and MySQL5?

This is just a point by point summary of how I've been tuning and tweaking our Joomla sites to get them running as quickly as possible. For reference, we run all our sites off a Rackspace dedicated server, with 1Gb RAM, a 2Ghz dual core Athlon, running Apache 2.0.x (current revision), PHP 5.0.x (current revision) and MySQL 5.0.18.
These are listed in terms of apparent speed increase - that is, not the sheer speed for the full page, but the speed before the page is usable to view content, even if not all features are loaded.
  1. PHP caching. I had been running eAccelerator, but switched to APC today, and it has made the system even faster than before, and eAccelerator was a big boost over uncached PHP. Joomla is a big complex system, so using precompiled code is a big time saver. I use a 128Mb in-memory cache, which is plenty for our needs.
  2. MySQL Query Caching. This one will vary depending on how dynamic your site is, and you can really kill the benefits by using the wrong extensions (any date/time based will need checking), but if you are serving pretty much the same queries each page load, it will drop the load times noticably.
  3. Template Image optimisation - template images really slow down the initial page load for first time visitors, so optimising the hell out of them makes sense. Remember that your template is probably not going to change as often as your story content, so you can afford to spend more time on optimising the images for it that you would otherwise. I recommend Irfanview, with the pngout plugin active for PNG images, and it isn't bad for JPG and GIF images either. Don't forget to ramp up the compression level of PNGs, and, if possible, reducing them to indexed pallettes.
  4. CSS compression. Easy one this - put a little script to output a gzipped version of your CSS file(s) and point your index.php at it. Example script below - I didn't write it, but it's short, to the point, and works.
             ob_start ("ob_gzhandler");
             header("Content-type: text/css");
             header("Cache-Control: must-revalidate");
             $offset = 60 * 60 ;
             $ExpStr = "Expires: " .
             gmdate("D, d M Y H:i:s",
             time() + $offset) . " GMT";
             header($ExpStr);
  1. Strip unneeded modules, components, mambots from Joomla. If you haven't used them, the impact on your loading time is minimal, but with more components/modules active, there are more points of failure, and Apache errors are slow!
  2. Scrutinise the Apache error log. It is amazing how many errors can crop up even with a fairly minimal Joomla install, and they don't necessarily affect the appearance of the page. Check your error log, especially if you are using custom components/modules, or any non-standard config settings. Once you've noticed any problems, it's time to fix the code creating them, and test thoroughly before uploading the fixed versions.
  3. Keep rechecking as you add/remove features, redesign or change any server configuration options. Even things like adding virtual servers in Apache can affect speed of the server, as a missed config setting can cause general Apache delays.

Should PHP run as a CGI script or as an Apache module?

There are two ways to configure Apache to use PHP:

  1. Configure Apache to load the PHP interpreter as an Apache module
  2. Configure Apache to run the PHP interpreter as a CGI binary

(PS: Windows IIS normaly configures as CGI by the way)

It is the intention of this post to provide you information relating to the configuration and recognition of each method. "In general" historically only one method or the other has been implemented, however, with the architectural changes made to PHP starting with PHP5, it has been quite common for hosting firms to configure for both. One version running as CGI and one version running as a Module. It is generally accepted more recently that running PHP as a CGI is more secure, however, running PHP as an Apache Module does have a slight performance gain and is generally how most pre-configured systems will be delivered out of the box.

What is the difference between CGI and apache Module Mode?

An Apache module is compiled into the Apache binary, so the PHP interpreter runs in the Apache process, meaning that when Apache spawns a child, each process already contains a binary image of PHP. A CGI is executed as a single process for each request, and must make an exec() or fork() call to the PHP executable, meaning that each request will create a new process of the PHP interpreter. Apache is much more efficient in it's ability to handle requests, and maaging resources, making the Apache module slightly faster than the CGI (as well as more stable under load).

CGI Mode on the other hand, is more secure because the server now manages and controls access to the binaries. PHP can now run as your own user rather than the generic Apache user. This means you can put your database passwords in a file readable only by you and your php scripts can still access it! The "Group" and "Other" permissions ( refer <a href="component/option,com_easyfaq/task,view/id,73/Itemid,268/" target="_blank">Permissions FAQ</a>

can now be more restrictive. CGI mode is also claimed to be more flexible in many respects as you should now not see, with phpSuExec ( refer " target="_blank Permissions under phpSuExec issues with file ownership being taken over by the Apache user, therefore you should no-longer have problems under FTP when trying to access or modify files that have been uploaded through a PHP interface, such as Joomla! upload options.

If your server is configured to run PHP as an Apache module, then you will have the choice of using either php.ini or Apache .htaccess files, however, if your server runs PHP in CGI mode then you will only have the choice of using php.ini files locally to change settings, as Apache is no longer in complete control of PHP.


Testing and Reviewing Your PHP Installation

Also known as "Everything you ever wanted and didn't want to know about PHP"

To find out the PHP interpreter mode and to generally test your PHP installation and to find out a vast amount of information about your PHP environment, supported utilities, applications and settings, you create a single PHP file containing only the following lines;

phpinfo();

This single line of code outputs an amazing amount of information, be warned.... <img src="wink.gif" alt="Wink" border="0" />

Save the file as any filename you wish, but with the ".php" extension. FTP it to your server and open it in a browser.

Other useful information

The following are PHP functions, that when run from a PHP File can provide some useful information, (less than the above option) many should run on most hosts, however many hosts disable some of these functions for security. No Guarantee's offered...

Again, as above, make a file, name it anything you wish but make sure it has the ".php" extension, copy and paste the following lines in to it and FTP to your server.

<?
echo "Hostname: ". @php_uname(n) .""; if (function_exists( 'shell_exec' )) { echo "Hostname: ". @gethostbyname(trim(`hostname`)); } else { echo "Server IP: ". $_SERVER['SERVER_ADDR'] .""; } echo "Platform: ". @php_uname(s) ." ". @php_uname(r) ." ". @php_uname(v) .""; echo "Architecture: ". @php_uname(m) .""; echo "Username: ". get_current_user () ." ( UiD: ". getmyuid() .", GiD: ". getmygid() ." )"; echo "Curent Path: ". getcwd () .""; echo "Server Type: ". $_SERVER['SERVER_SOFTWARE'] . ""; echo "Server Admin: ". $_SERVER['SERVER_ADMIN'] . ""; echo "Server Signature: ". $_SERVER['SERVER_SIGNATURE'] .""; echo "Server Protocol: ". $_SERVER['SERVER_PROTOCOL'] .""; echo "Server Mode: ". $_SERVER['GATEWAY_INTERFACE'] ."";
?>

The Joomla! HISA or Joomla! Tools Suite can also assist to determine which mode your server in running in, also providing a large amount of other related information including recommendations on configuration.

Joomla! Tools Suite (JTS) is a complete suite of Tools to help you troubleshoot and maintain Joomla! and include the "HISA" script. Download JTS Here

Joomla! Health, Installation and Security Audit (HISA) is a single standalone script that provides purely configuration information. Download HISA Here

Another Indirect method, and possibly not 100% reliable, is that if you are unable to make use of .htaccess on Linux hosting and Apache based servers then you are either running in CGI mode or your host has disabled the use of .htaccess even if your server is running PHP as an Apache Module.

Remove these files immediately after use, the information contained in their output is extensive and explicit regarding your PHP and server configurations, it will help those wishing to cause your site harm

For those wishing to know more about "How To..."

Running PHP as an Apache module
To configure Apache to load PHP as a module to 'parse' your PHP scripts, the httpd.conf needs to be modified, typically found in "c:\Program Files\Apache Group\Apache\conf\" or "/etc/httpd/conf/".

Search for the section of the file that has a series of commented out "LoadModule" statements. (Statements prefixed by the hash "#" sign are regarded as having been commented out.) If PHP is running in "Apache Module" Mode you should see something very similar to the following;

LoadModule php4_module "c:/php/php4apache.dll"

Apache 1.x

For PHP5

LoadModule php5_module     C:/php/php5apache2.dll
or (platform dependant)
LoadModule php5_module /usr/lib/apache/libphp5.so

For PHP4

LoadModule php4_module libexec/libphp4.so
or (platform dependant)

LoadModule php4_module C:/php/php4apache.dll

and

AddModule mod_php4.c

or

AddModule mod_php5.c


Apache 2.x

For PHP5

LoadModule php5_module     C:/php/php5apache2.dll

or (platform dependant)

LoadModule php5_module     /usr/lib/apache/libphp5.so

For PHP4

LoadModule php4_module     libexec/libphp4.so

or (platform dependant)
LoadModule php4_module C:/php/php4apache.dll

and
AddModule mod_php5.c

or
AddModule mod_php4.c

Note:
Don't worry that you can't find a "mod_php4.c" or "mod_php5.c" file anywhere on your system. That directive does not cause Apache to search for the file on your system. For the curious, it specifies the order in which the various modules are enabled by the Apache server.

If you're using Apache 2.x, you do not have to insert the AddModule directive. It's no longer needed in that version. Apache 2.x has its own internal method of determining the correct order of loading the modules.

Now find the "AddType" section in the file, and add the following line after the last "AddType" statement:

AddType application/x-httpd-php .php

If you need to support other file types, like ".php3" and ".phtml", simply add them to the list, like this:<

AddType application/x-httpd-php .php3
AddType application/x-httpd-php .phtml

Run a syntax check and if all is ok, restart Apache...


Running PHP as a CGI binary
To configure PHP to run as a CGI, again you will need to configure the httpd.conf, but confirm that the above settings are not also configured, unless you now what you are doing you can generate yourself "HTTP 500" errors. Search your Apache configuration file for the "ScriptAlias" section.

Add the following line below after the ScriptAlias for "cgi-bin".

Note:

The location will depend on where PHP is installed on your system, you should substitute the appropriate path in place of "c:/php/" (for example, "c:/Program Files/php/").

ScriptAlias /php/ "c:/php/"

Apache again needs to be configured for the PHP MIME type. Search for the "AddType" section, and add the following line after it:

AddType application/x-httpd-php .php

As in the case of running PHP as an Apache module, you can add whatever extensions you want Apache to recognise as PHP scripts, such as:

AddType application/x-httpd-php .php3
AddType application/x-httpd-php .phtml

Next, you will need to tell the server to execute the PHP executable each time it encounters a PHP script. Add the following below any existing entries in the "Action" section.

Action application/x-httpd-php "/php/php.exe"

If you notice, we have used the "ScriptAlias" reference, "/php/" portion will be recognised as the scriptAlias configured above, this is sort a path alias which will correlate to your PHP installation path configured previously. In other words, don't put "c:/php/php.exe" or "c:/Program Files/php/php.exe" in that directive, put "/php/php.exe", Apache WILL work it out if correctly configured.

Configuring the Default Index Page
This section applies to all users, whether you are loading PHP as a module or running it as a CGI binary, and has been seen often enough to warrant a mention.

If you want to make your PHP script execute as the default page for a directory, you have to add another line to the "httpd.conf". Simply search for the line in the file that begins with a "DirectoryIndex" and add "index.php" to the list of files on that line. For example, if the line used to be:

DirectoryIndex index.html

change it to

DirectoryIndex index.html index.php
If you still wish .html files to be executed before .php files

or
DirectoryIndex index.php index.html
If you wish .php files to be executed before .html files

The next time you access the site or a directory within a site without a filename, Apache will "auto-magically" deliver "index.php" if available, or "index.html" if "index.php" is not available.

Why shouldn't I use PHP safe_mode?

Overview Enabling safe_mode is not needed if other reasonable security precautions are followed. Using safe_mode for web site security is a poor compromise in a bad situation. It may make sense in some situations, but there is almost always a better way. Because safe_mode in some sense only gives the illusion of safety, it will be removed from PHP starting with version 6.0.

The Joomla! core works fine with or without PHP safe_mode. The one exception to this rule is the installation script. This is because safe_mode, by design, turns off the PHP functions that enable easy uploading via a Web browser. If you do use safe_mode, and need to perform installs via the Web browser, temporarily turn safe_mode OFF, and turn it back ON when finished.

Some third-party extensions may require the specific PHP functions that are blocked by safe_mode. Such extensions should be carefully evaluated to be sure you understand exactly why they require such powerful and potentially dangerous functions.

From the official PHP site

"The PHP safe mode is an attempt to solve the shared-server security problem. It is architecturally incorrect to try to solve this problem at the PHP level, but since the alternatives at the web server and OS levels aren't very realistic, many people, especially ISP's, use safe mode for now." More Information

  1. Official PHP Manual: PHP Security and Safe Mode Configuration Directives
  2. Official PHP Manual: PHP Functions restricted/disabled by safe mode

Development

How do I setup a secure demo site?

In /includes/version.php look for:

/** @var string Whether site is a production = 1 or demo site = 0 */
var $SITE = 1;
/** @var string Whether site has restricted functionality mostly used for demo sites: 0 is default */
var $RESTRICT = 0;

For a demo site it is advised to following:

/** @var string Whether site is a production = 1 or demo site = 0 */
var $SITE = 0;
/** @var string Whether site has restricted functionality mostly used for demo sites: 0 is default */
var $RESTRICT = 1;
$SITE = 0
// Allows multiple user logins with only one account. By default Joomla! 
// allows only one active session per account as a security feature.
$RESTRICT = 1
// Disables those logging in, both Front-end and Back-end from changing 
// user details - like password and username

These settings are used on the official demo site http://demo.joomla.org

You should also make all files and folders nonwriteable - especially the configuration.php file. Also recommend you setup an automatic cron job that refreshes the database at a set interval (in our case 60mins) from a db script.

How can I view a live site while developing, but hide it from others?

Introduction

The method described below should be used for relatively minor modifications, such as adjusting menus or quickly reorganizing content sections. More complex tasks, such as installing new components or adjusting complex configuration settings should be performed and tested on a development server first. Not only does this keep your public site up and running, but it also lets you test at your leisure, thus reducing errors. One way to do it is to create a sub-domain (i. e., dev.yourdomain.com) and install Joomla! there just as it is installed on your public site.

Directions

1. Login to the administrator section, and choose: Site > Global Configuration.

2. The first option you'll see is is to set the site offline. Choose "Yes" and press the Save button. This will hide prevent display of all site pages, and replace them with the following message:

"This site is down for maintenance. Please check back again soon. message instead."

3. While you are logged into the "back end" administrator system, you can still view the "front end," by choosing Site > Template > Preview. This will display the site as it would appear to users along with a warning at the top that the site is down for maintenance.

Site Recovery

Help! My site's been compromised. Now what?

Directions

  1. Change all relevant passwords: Assume your passwords have been harvested and immediately change all critical passwords, including shell access, FTP access, Joomla! Administrator accounts, and the database account.
  2. Check raw logs: Identify when and how the attackers gained access to your site by carefully reviewing your raw server logs. Make careful note of the date/time and names of attacked files. Note that these logs may have been deleted or altered, so a lack of evidence does not prove a lack of activity.
  3. List recently modified files: Before making any changes to your site, generate a list of recently modified files. Here's a php script that will list the files for you. Remove this script as soon as you have your list and don't publish a link to it!
  4. Note suspicious newly-created files: Use this list to identify new files that don't belong. Pay particular attention to their creation and modification dates, and correlate them to the dates of attacks shown in your log files.
  5. Note suspicious recently-modified files: Check the modified files list for any files that were recently changed. Pay particular attention to the modification, and correlate them to the dates of attacks shown in your log files.
  6. Check for bogus CRON Jobs: Hacked cron jobs can be setup to reinfect your site over and over again.
  7. Coordinate with your host: If you have identified how you were cracked, report the method to your host. If you are on a shared server, you may habe been attacked through another vulnerable site on your server. Report this to your host. A reputable host will appreciate your efforts in this area.
  8. Delete the entire public_html directory: This is the best way to guarantee that every potential vulnerability in that site is removed.
  9. Delete related database records: This step may only be possible if you have good backups. Simple script kiddies, who are only trying to mark your index page, may not attack your database, but professionals are usually very interested in confidential data, such as passwords. They may pose as script kiddies to avoid suspicion while repeatedly harvesting confidential information from your database.
  10. Reinstall everything: Use pre-crack backups. If you don't have good backups, go on to step 10.
  11. Reset critical passwords again: You must reset your passwards again now that your server is finally cleaned of any possible, hidden trojan horses.
  12. Rebuild site: If you are unable to rebuild from clean backups, rebuild your entire site using original, pre-crack installs. Use only the latest stable versions of all software, and check the List of Vulnerable Extensions
  13. Review security processes: Follow standard security precautions for important settings in php.ini, globals.php, configuration.php, .htaccess, etc.
  14. Review backup processes: If you don't already have one, add a dependable backup process to your site administration practices.
  15. Stay watchful: Attackers often return repeatedly. Closely monitor your raw logs for suspicious activity.

How do I reset an administrator password?

Introduction

Note: This method is for Joomla versions up to and including 1.0.12Joomla 1.0. For later versions of Joomla and Joomla 1.5.xx versions please use this (FAQ)

Because passwords are stored using a one-way MD5 hash which prevents recovering the password, you cannot recover an existing password, but you can reset it to a new password by editing the password field in the database. In the following directions, you will set the password MD5 value to a known value and then log-in using the password that matches that value. Once logged in, you can change the password again using normal Joomla! user access screens.

Enhanced Password Encryption Note Joomla! 1.0.13+ and Joomla! 1.5.x This method works with the new salt-enhanced passwords. This is because Joomla! will automatically update passwords in the earlier format.

Directions

1. Use a MySQL utility such as phpMyAdmin or MySQL Query Browser .

2. Open the correct database and select the table, jos_users . (Change default table prefix, 'jos_' to your table prefix if it is different.)

3. Select the record (or table row) for your administrator account. (The default Super Administrator is user number 62.)

4. Copy and paste a known MD5 hash into the password field. You can use one of the below examples. Warning: You must paste the password's hash value, not the password itself. You can use any of the following hashs, or create your own using one of the MD5 tools listed below.

password = "MD5 hash of password"
------------------------------------------------------
admin = 21232f297a57a5a743894a0e4a801fc3
secret = 5ebe2294ecd0e0f08eab7690d2a6ee69
OU812 = 7441de5382cf4fecbaa9a8c538e76783

5. Save the user record.

6. Point a browser to your site and log in using the Super Administrator account you just modified.

7. IMPORTANT: Once logged in, use the Joomla interface to change the password to one that only you know. This step is vital as it will 'salt' your new password, thus adding an additional level of security on top of the MD5 hash.

Note: This technique can be used to modify any other accounts password. You can also use it to change Usernames.

Generating your own MD5 hash from a password of your choice

Alternatively, you can set the password to a value of your own choice. Use tools, such as the following, to create your own strong hashed password. Use the above directions once you've generated a hash with these tools.

Online MD5 hash creation tools

Free MD5 utilities for download

Other MD5 tools

  • There are many free online and downloadable MD5 utilities. Google "MD5 hash tool"

How do I find exploits using the *NIX shell?

Check the active processes

Use the "ps" command to look for odd or unknown processes, if you aren't sure what to look for there, user "netstat -ae | grep irc" and/or "netstat -ea | grep 666" and look for ports 6666, 6667, 6668, 6669, these are common ports used for running IRC bots, they may have the name "irc" listed against them, or may have "httpd" or sometimes other regular services names.

Check crontab

Check your crontab and see if there is a strange entry, these are used in many exploits to restart IRC bots, even when admins or automated process monitors are used to kill a rogue process.

Check for hidden files or directories

Check for hidden files or directories you dont expect to see, those starting with "." (dots) and also look for ". " (dot, space) often favored to try and catch searches for hidden directories.

Other examples of searches that may help pin down exploits and/or unexpected files and folders:

find /home -type f | xargs grep -l MultiViews
find . -type f | xargs grep -l base64_encode <<< this can produce false positives, it is valid in many mail/graphics scripts
find . -type f | xargs grep -l error_reporting
find / -name "[Bb]itch[xX]"
find / -name "psy*"
ls -lR | grep rwxrwxrwx > listing.txt

What are these strange (URL-Encoded) characters doing in my code?

Overview

Attackers sometimes hide code away from prying eyes by URL Encoding it.

The purpose of URL Encoding is to allow non-URL compatible characters to be passed via the URL. There are many legitimate reasons for doing this, such as hiding email from spammers, dealing with spaces in file names. etc.

However, if you find odd, URL-encoded text in your site's files, you should investigate immediately. URL encoded text is very easy to translate using PHP, javascript, or one of the many free, online translators.

Here are some trivial, non-functioning examples of URL Encoded text:

Original URL Encoded
this line has spaces this%20line%20has%20spaces
eval(evil_script(http://www.evilsite/?evilscript.pl")); %65val%28%65%76il_%73cri%70t

%28%68tt%70%3A//%77%77%77. %65%76il%73ite/%3F%65%76il%73

cript.%70l%22%29%29%3B

Resources

  1. Text Unescape Utility
  2. HTML URL-encoding Reference