chkrootkit
loresecurityIT support
The Unix rootkit detector written in 1997 by Brazilians Nelson Murilo and Klaus Steding-Jessen - a shell script that uses ordinary system tools to look for the signatures and behavioural traces of known rootkits, and still maintained decades later.
It is probably the most widely deployed piece of security software ever written in Brazil: packaged by essentially every Linux distribution, ported across the BSDs, Solaris and others, and reached for by administrators who suspect a compromised machine. The design decision that made it last was choosing to be a portable script over standard utilities rather than a binary tool - it runs where nothing else will install, which is exactly the situation you are in when you need it.
Also known as: nelson murilo, klaus steding-jessen, rootkit detector