Virus writers have unleashed a worm that attempts to delete MP3 files from infected machines.

The Deletemusic worm spreads via removable devices. As soon as an infected device is accessed the worm will be executed. Thereafter it copies itself onto all drives, including removable devices, and executes whenever Windows is started up on compromised PCs.

The worm is spreading, albeit modestly, causing a small number of infections. Anti-virus vendors such as Symantec rate it as a low to no-risk threat.

Malware capable of zapping MP3 files is rare but far from unprecedented. The Klez-F worm, for example, which was widespread in 2002, overwrote MP3 files (and other file types) on certain days of the month. The Scrambler worm was programmed to scramble MP3 files to sound like a scratched record while the Mylife-G worm overwrote MP3 files with the words "my lIfE".

None of these items of malware made any attempt to differentiate between legitimate and illegitimately obtained music files.

The authors of Deletemusic - the latest example of the genre - remain unknown. Vigilante virus writers or mischief makers are the probable perps though the involvement of music industry itself in some form or another isn't entirely implausible, given past form.

Either way the consequences of infection are serious for infected Windows users.

"With so many people relying on their PCs to store their digital music, rather than physical CDs, a worm capable of deleting an entire MP3 collection could leave someone thousands of pounds out of pocket," said Orla Cox, Security Operations Manager, Symantec Security Response. "We would recommend all users with MP3 files on their PCs to remain cautious about the removable media devices they are using in their machines." ®