The icabar.exe file which is designed to startup the Citrix MetaFrame administration toolbar allows an attacker to escalate privileges in Windows 2000 and below in the default configuration and in Windows 2003 in some special circumstances.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/68652/citrix-escalate.txt
Source: https://packetstormsecurity.com/files/68652/citrix-escalate.txt.html