Date Found: 19th June 2007

Successfully tested on: version 5.5.2

F5 Networks has confirmed the following versions to be vulnerable:

FirePass versions 5.4 - 5.5.2
FirePass versions 6.0 - 6.0.1

Description:

F5 Networks FirePass 4100 SSL VPN is vulnerable to XSS within the "backurl" parameter processed by the "download_plugin.php3" server-side script.

No authentication is required to exploit this vulnerability.

Consequences:

An attacker may be able to cause execution of malicious scripting code in the browser of a user who visits a specially-crafted URL to an F5 Firepass device, or visits a malicious page that makes a request to such URL. Such code would run within the security context of the target domain.

This type of attack can result in non-persistent defacement of the target site, or the redirection of confidential information (i.e. admin session IDs) to unauthorised third parties. 

Severity: Medium/High

Credits: Jan Fry [jan.fry [at] procheckup.com] and Adrian Pastor [adrian.pastor [at] procheckup.com] of ProCheckUp Ltd 

Fix:

F5 Networks has issued SOL7498:
https://support.f5.com/kb/en-us/solutions/public/7000/400/sol7498.html 

More information, including proof of concept can be found on:
https://www.procheckup.com/Vulnerability_PR07-13.php