There are several ways to find the rootkits you desire. Since I am not use to providing URLs for hacking sites, I will defer, but instead offer the following: Try google.com or other search engines. After I checked, there seems to be a good amount of information and links that can help you.
I will also suggest you check your local ISSA (www.isc2.org) or FBI Infragard (www.infragard.com). Both sources can help with your legitimate request.
For more information on this topic, visit these other SearchSecurity.com resources:
Best Web Links: Hacker tools and utilities
Best Web Links: Network assessment
This was first published in September 2002