A perl script to backdoor chkrootkit rendering it useless. Tested on chkrootkit version 0.44 running on Red Hat enterprise 3.
You can download it from the following link: https://packetstormsecurity.com/files/download/44604/anti-antirootkit.pl.txt
Source: https://packetstormsecurity.com/files/44604/anti-antirootkit.pl.txt.html