Security experts have cracked the password needed to retrieve files encrypted by a Trojan horse, dubbed Arhiveus-A, that claimed a number of victims following its appearance on the net last week.

The malware scoops up files in infected users' 'My Documents' folders and packs them in an encrypted file called EncryptedFiles.als.

Users are informed that they won't be able to recover their documents without making purchases at one of three online drug stores, in return for which they'll be furnished with a "30 digit" pass phrase.

However, anti-virus analysts at Sophos have disassembled the Arhiveus Trojan and discovered that the password it uses to encrypt data is "mf2lro8sw03ufvnsq034jfowr18f3cszc20vmw".

So-called ransomware attacks, as practiced by Arhiveus-A, are becoming more common as virus writers turn to sneakier and sneakier activities in order to scrape a living. In March 2006, the Zippo Trojan horse demanded $300 from victims for the safe return of their encrypted data. The Ransom-A Trojan horse threatened to delete compromised files one-by-one until extortion demands were met. ®