Arbitrary Variable Overwrite in eShop WordPress Plugin

High-Tech Bridge Security Research Lab discovered security vulnerability in eShop WordPress Plugin, which can be exploited by remote attacker to overwrite arbitrary PHP variables within the context of the vulnerable application.

The vulnerability exists due to insufficient validation of user-supplied input in “eshopcart” HTTP cookie. Successful exploitation of this vulnerability type may result in arbitrary PHP code execution (RCE), however in this case we can only overwrite string variables within the scope of ‘eshop_checkout()’ function in ‘/wp-content/plugins/eshop/checkout.php’ file. This reduces our current vectors of exploitation to Full Path Disclosure and Cross-Site Scripting.

Below is a simple PoC that overwrites contents of the “wpdb” PHP variable, which causes an error in code and discloses full installation path:

GET /shopping-cart-2/checkout/ HTTP/1.1
Cookie: eshopcart=wpdb%3d1%7C;

Another PoC triggers the XSS vector and executes JS pop-up box displaying “ImmuniWeb”:

GET /shopping-cart-2/checkout/ HTTP/1.1
Cookie: eshopcart=phone%3dsdfg’"><script>alert(/ImmuniWeb/)</script>