The spam is a short, 30-second MP3 file recorded at low bit-rate with a synthetic female voice promoting a particular stock; the voice heavily distorted to avoid signature-based anti-spam approaches (click here to listen to an edited sample of MP3 spam). Spammers are taking advantage of the fact that the MP3 format is one of the most common in use today and that most anti-spam solutions do not handle attachments very well because they do not actually analyze the attachment content.

"MP3 spam is a natural progression from PDF and Excel spam whereby spammers are exploiting a new file format to be able to send spam. This is their latest attempt to evade anti-spam filters. There is also a social engineering aspect to this tactic because people frequently share MP3 files," David Vella, Director of Product Management, said.

To address the MP3 spam threat administrators need to deploy as many anti-spam techniques as possible, including Bayesian filtering, while at the same time maintaining a very low level of false positives. Additionally, administrators can block attachments or place restrictions on allowable sizes to weed out unwanted material. MP3 spam: The latest trend

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