Microsoft has issued Service Pack 2 for ISA Server 2000. This includes patches for all previously reported vulnerabilities as well as older hot fixes, where some address potential security issues.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/33554/sa11799.txt
Source: https://packetstormsecurity.com/files/33554/Secunia-Security-Advisory-11799.html