MP3 spam makes a comeback

The messages play a sound clip advertising the pharmacy site

Security experts have warned of a new spam attack using MP3 files to advertise online pharmacy services.

Researchers at MessageLabs said that the title of the sound file is the same in each message, and advertises Viagra. On opening the message, the recipient hears a sound clip advertising the pharmacy site.

The message itself contains no attack code and the run is believed to be a regular spamming operation, but the attack is catching the attention of security experts.

MessageLabs senior researcher Paul Wood noted that the technique of sending spam in MP3 files is somewhat dated, and has largely fallen out of favour.

"Today, of course, we still see various file formats being used in spam messages, but not nearly as much as in 2007 and 2008," Wood noted in a blog post. "The favoured approach now is to include a hyperlink that leads to spammers' web sites."

The attack is the second recently discovered spam operation to dig up old methods of delivering junk mail. Earlier this week researchers noted that the 'Donbot' malware botnet was resorting to the classic pump and dump stock trick in order to generate revenues for its operators.