I recently (re)stumbled upon this:  Linux Trojan Goes Unnoticed For Almost A Year (Unreal IRCd)Yes, I know that adding some random PPA/software from an untrusted source is asking for trouble (or worse). I never do that, but many do (many Linux blogs and tabloids promote adding PPAs for fancy apps, without warning that it may break your system or worse still, compromise your security.) How can a trojan horse or a rogue application/script be detected and removed?
How to detect and remove a Linux trojan?
security;malware