After the PDF, Excel and ZIP based spam outbreaks we now have a stock spam outbreak based on the popular MP3 format for delivering audio. The messages are between 85kB and 150kB and contain an MP3 in poor quality at a 16 kbps bitrate and 11 KHz sample rate with an average length of 30 seconds. To avoid email filters these files are highly randomized.
The attachment files names range from well known artists like smashingpumpkins.mp3, bbrown.mp3, bspears.mp3, gloriaestefan.mp3, beatles.mp3 to and some obvious poplar sound names like answeringmachine.mp3, coolringtone.mp3, listentothis.mp3. The subject only contains Fwd: or Re:.
MX Lab protects clients against this new form of spam. The outbreak accounts for around 7-10% of all spam, globally, over the past 18 hours. The first MP3 spams where detected on October 17, 2007, 21:24 GMT.