Here's a first: a Trojan horse that actually helps security pros do their jobs.

Analysts at SophosLabs...have discovered a spyware-borne Trojan, dubbed Troj/Erazer-A, that seeks out and destroys movie and music files that it suspects to be illegal copies transmitted via peer-to-peer (P2P) file sharing networks..."The Erazer Trojan is a vigilante worthy of a Charles Bronson movie, taking the law into its own hands...Trojan Erazer could be dangerous because it tries to turn off antivirus applications and other security tools...its methods are worrisome because it deletes files, steals information, adds itself to the registry, and then drops more malware on the target system.