Old Exploits Still Do the Trick

We are all aware that patching is very important. Manywebsites, however, take the risk of not updating their software for variousreasons: it requires manual modifications, adjustment of the current code towork with the changes, the layout gets broken... In other words- they are lazy.

Knowing this, cybercriminals try their luck and brute forcemany websites in hopes of hitting the unpatched ones.

If you happen to find a new module in your outdated Joomlainstallation called "mod_404" or "mod_modules"- you are probably a victim ofthe following attack, which started a few weeks ago.

This attack was divided into several stages:

Following the initial infection (using one of several patchedJoomla vulnerabilities)the cybercriminals attempt to expand the attack by searching for other websiteshosted on the same webserver in order to inject them with an IFRAME whichredirects to the following obfuscated PHP script:

Snippet obfuscated PHP script
Snippet obfuscated PHP script


After several iterationsof eval, readable PHP code is revealed:

Snippet d-obfuscated PHP script
Snippet d-obfuscated PHP script

The script does several things which aren't particularlynoteworthy, up to the point where it accesses the page"hxxp://wsouser.ru/iframe1.txt" to receive an updated URL which is added into JavaScriptcode that is sent to the victim:

Snippet JavaScript code
Snippet JavaScript code

The code collects basic information about the user's browser,ensures it's the first visit of the victim to the site, and loads yet anotherIFRAME from a different URL.

Snippt PHP script
Snippt PHP script

The script "red_one_f5.php" loads a different file,"iframe2.txt", to receive the next hop of the attack. This iframe redirects thebrowser to "hxxp://belkabelka.in/?id=red", which hosts a TDS (TrafficDistribution System) named "Keitaro TDS".

Since the TDS is configurable, the cybercriminal canredirect the traffic to any URL in order to avoid detection by securityvendors, in this case the traffic is redirect to the Neutrino Exploit Kit.

It's important to note that the Joomla CMS is a very popularsystem. There are almost 2 million websites which use the Joomla platform andso it makes sense that many of these websites that don't keep their systemsup-to-date will remain vulnerable to such automated attacks.

This isn't a lone case of its kind- other than the many hopstaken on the way to the payload, there is nothing particularly sophisticated orchallenging here, and that is perhaps the most troubling part about it. This is yet another reminder that thesetechniques are not gone from the world- they are still here; and probably hereto stay. Please keep that in mind andkeep your web applications up-to-date!

Written by Anat Davidi and Daniel Chechik

Trustwave reserves the right to review all comments in the discussion below. Please note that for security and other reasons, we may not approve comments containing links.