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Industry Hears First 'Singing Spam'

Spammers hide messages in MP3 files to avoid detection

Even your iPod is no longer safe from spam.

Security firm MessageLabs today reports that it has spotted a massive run of spam sent out in the form of MP3 files and masquerading as music clips from popular artists. This is the first instance of a large distribution of spam hiding inside sound files, the researchers say.

"On October 17, MessageLabs intercepted the first copies of a fairly large spam run likely to be conducted by the same group responsible for the earlier PDF spam," the report says. (See Researcher Raises Alarm Over PDFs.)

"This time, the attachment was an audio MP3 file, containing a rusty-sounding, 25-second voice-over touting the latest stock offering from 'Exit Only Incorporated,' MessageLabs says. "It is likely that the voice was synthesized using a very low compression rate of 16 kHz to keep the overall file size small, at around 50 KB."

The spam run continued for about a day and a half, accounting for around a half million spams per hour -- about 5 to 10 percent of the spam sent during that period, MessageLabs says. The audio files were being randomized automatically by changing name and file sizes, sometimes with the same message repeated up to three times within the attachment.

The MP3 files fooled users with attracting and deceptive names, such as bartsimpson.mp3, beatles.mp3, britney.mp3, familyguy.mp3, elvis.mp3, and ringtones.mp3. The files also fooled most anti-spam tools, which typically cannot detect spam hidden in a sound file.

Many of the computers used to send the MP3 files were computers known to be infected with the Storm Trojan, leading MessageLabs to conclude that they are part of the ongoing pump-and-dump scam that has been riding on Storm for months. Botnets, particularly Storm, have been using an increasingly wide and innovative range of formats for distributing spam, including Zip and PDF file formats, the researchers note.

MessageLabs postulated that MP3 spam might follow a path similar to that of image spam, which flooded email boxes earlier this year, then morphed into different sorts of exploits, such as attachments hiding on popular photograph (or, in MP3's case, music and video) sites.

"Since image spam evolved from an email-based attachment to an image hosted on free image-hosting sites such as Imageshack, it is only a matter of time before the spammers apply the same approach to audio spam, and perhaps experiment with video spam," MessageLabs posited.

"Maybe they will upload the multimedia message to free hosting sites such as YouTube, Google Video, MySpace, or any number of similar sites competing in this new media market," MessageLabs said. "It will be interesting to speculate when we may expect to see spam containing links to hosted video clips promoting penny stocks."

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  • MessageLabs Ltd.
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