Security Experts Name Mysterious Trojan: Stumbler

The trojan horse that has been causing confusion and concern among security researchers for over a month now has been dubbed 'Stumbler' by experts at Internet Security Systems (ISS).

As reported earlier, Stumbler embeds itself in Unix systems and seems to be part of a concerted effort to map Internet-connected networks using port scanning techniques. A copy of the trojan horse was finally captured Wednesday, and investigation of its code began Thursday.

After additional analysis, researchers at the security firm Intrasec tentatively concluded late Thursday that the captured sample is a copycat of the real trojan, created to mimic the behavior of another trojan or worm. In fact, said Intrasec, Stumbler seems to be based on a variety of media reports that have described the malware's hypothetical behavior and output.

Unsure as of yet how to describe Stumbler -- trojan, backdoor, zombie, or worm -- Intrasec called for additional analysis, and warned that although this variation is benign, modified versions could, in fact, prove malicious.