A computer worm that first appeared more than two years ago is still a threat, even though security experts were successful in mitigating possible damage.

The Conficker worm, which originally appeared in 2008, is an example of a "botnet" type of malware. It infects a computer by being downloaded from the Internet or from a mass storage device that has a copy. Unlike malware that simply uses a host computer to send spam or steal personal information, Conficker is flexible - it can be asked to do a variety of things. That flexibility is what makes it so dangerous, according to a report from the Conficker Working Group, a team of experts that came together to tackle the malware.