A fifth variant of the Slapper OpenSSL exploit worm has been spotted in the wild, but won't be posing much of a risk since most vulnerable systems have already been infected or patched by now. "Mighty" is closely related to Slapper.D, but uses an IRC channel to receive commands, as opposed to the P2P network other variants have relied upon. The IRC backdoor code is based on the 'Age of Kaiten' bot. According to VirusList.com, the worm is about 19kb and has spread to some 1600 systems. F-Secure and ISS are both tracking the various modifications of Slapper; in total, some 20,000 servers were hit, a fraction of the 400,000 IIS boxes infected by Code Red last year.
(N-Stalker Security Force)