source: http://www.securityfocus.com/bid/11779/info

IPCop is reported susceptible to an HTML injection vulnerability in its proxy log viewer. This issue is due to a failure of the application to properly sanitize user-supplied input prior to including it in dynamically generated web pages.

This vulnerability allows remote, attacker-supplied malicious HTML or script code to be displayed to administrative users. This code would be executed in the context of the affected Web application. It is conjectured that it may be possible for attackers to cause administrative actions to be executed on their behalf when an administrator views the Squid logs. Theft of cookie-based authentication credentials and other attacks are also likely.

Version 1.4.1 of IPCop is reportedly vulnerable. Other versions may also be affected.

GET /<script>alert('XSS_PoC')</script> HTTP/1.1
Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*
Accept-Language: en-us
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
Host: example.com
Connection: Close