FreeScout is a self-hosted help desk and shared mailbox. Versions prior to 1.8.128 are vulnerable to OS Command Injection in the /public/tools.php source file. The value of the php_path parameter is being executed as an OS command by the shell_exec function, without validating it.

This allows an adversary to execute malicious OS commands on the server. A practical demonstration of the successful command injection attack extracted the /etc/passwd file of the server. This represented the complete compromise of the server hosting the FreeScout application.

This attack requires an attacker to know the App_Key of the application. This limitation makes the Attack Complexity to be High. If an attacker gets hold of the App_Key, the attacker can compromise the Complete server on which the application is deployed.

Version 1.8.128 contains a patch for this issue.