Web and email management specialist Email Systems has noted a mass global outbreak of MP3 attachment spam, which began at around 9pm GMT on Wednesday October 17th and has subsequently been responsible for between 7% and 10% of all spam, worldwide.
The emails are appearing in significant volume and are MP3 voice file attachments which promote specific stocks.
To date, no virus threat has been found in these messages.
The messages are uncommonly large for spam – even when compared to other types of spam which carry attachments – such as .pdf or image spam. The files average around 85kb but have been captured up to 147Kb in size.
The messages themselves are much larger than "traditional" spam and are even larger than both image spam and PDF spam.
Average message size is around 85KB but files have been recorded up to 147KB. The audio lasts around 30 seconds although sound quality is extremely low, at around a 16 kbps bitrate and 11 KHz sample rate.
The majority of messages have no content in the subject line – simply containing either "Fwd:" or "Re:". Some emails do contain the name of the file attachment, which appear to fall into a number of categories, from those that are presented as personal (ie weddingsong.mp3), to citing specific artists or tracks (ie santana.mp3, bspears.mp3, beatles.mp3) or referencing sounds that may appeal to a broad audience (ie coolringtone.mp3, listentothis.mp3). The message contents are largely empty.
Greg Miller, VP Sales & Marketing for Email Systems commented:
“The inflated files sizes and rapid escalation in volume that has characterised this outbreak positions this as a dual threat for unprotected businesses, as it is potentially particularly bandwidth sapping. Once again, this validates the rationale for Email Systems managed services which exist on the internet to provide a buffer between the incoming mail and the email user, ensuring that only the clean filtered email is allowed to hit the network.”