One can never underestimate the importance of upkeep and routine maintenance, especially when it comes to web sites and applications. When we do not practice due diligence or neglect our web applications, hackers can find holes, weaknesses, and exploits in our so-called “secure” sites.
That holds even more true when it comes to “canned” applications such as Joomla. We have learned that Joomla version 2.5, and 3.1.x have a security hole that can allow anyone to upload malicious files through your application.
The malicious files can perform cross-site scripting (injecting a string of code to your web pages, which can redirect users to a phishing site), or distribute malware or Trojan files that can affect your visitor’s computers.
The security hole in Joomla is its Media Manager, which offers you a tool to upload files to the website. This is a necessary function in a CMS such as Joomla. Joomla comes with its own filtering mechanism that prevents anyone uploading files with specific extensions that can be malicious in nature. Files with extensions such as .exe or .php should not be uploaded as they can infect your web application.
However, the bug is that a trailing dot on a file name can circumvent the filtering mechanism. Normally Joomla will prevent the upload of files with a .php extension such as document.php. However, include a period at the end, such as document.php., and the file no longer fits the .php criteria.
Nasty bug to say the least. What is more frightening is that you do not have to be a registered user or have administrative privileges to the application to exploit the bug. If the Media Manager was set to be available to the public, anyone can inject your site with a malicious file.
The simplest way to solve this problem is to go to Joomla’s website, download the most recent version, and upgrade. This should have the latest patch to this security threat.
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31626
http://www.joomla.org/announcements/release-news/5505-joomla-3-1-5-stable-released.html
If an upgrade is not an option for you, you can manually add the code that will prevent users from uploading files to your application with a trailing dot.
Navigate to /Libraries/Joomla/Filesystem and open file.php. Scour the code to find where the makeSafe function starts. Add the line:
// Remove any trailing dots, as those aren’t ever valid file names.
$file = rtrim($file, ‘.’);
If this line already exists then your Joomla application is immune to this specific security hole.
That doesn’t mean that you should not routinely follow up on the most recent news concerning your web applications. To really secure your site it is important to stay informed of the most recent patches for your web application.
Here are links you may want to check to stay up-to-date with Joomla’s security fixes. Keep in mind that some security patches may not apply to you depending on the version you are running.
http://docs.joomla.org/Vulnerable_Extensions_List
Let me lastly say that we here at Winhost take this threat seriously. As of today, we have updated our App Installer to the most recent Joomla version (3.1.5) with the security patch installed. If you installed your Joomla application with this newest release, you are protected from this specific threat, however if you have installed an older version from us you may want to check file.php within Joomla and make sure the appropriate line is added.