The latest step in the evolution of spam: the mass mailing of MP3 audio files. This trend was first detected in European mail traffic by the company’s spam analysts.
The spam circulating in MP3 files is so-called stock spam, which is designed to artificially increase the price of certain stocks by advertising them. This type of spam first appeared in August of last year and has since then become widespread. It is notable that spammers actively use a number of innovative methods when sending this type of spam in an attempt to evade detection by spam filters: for instance, stock spam was sent in the first mass mailing to use specially crafted graphics files containing background ‘noise’, and in .pdf files, which at the time could not be detected by spam filters.
From Kapersky Labs