Report on email threats: massive botnets spread PDF and malware

Commtouch released its Email Threats Trend Report for the second quarter of 2007, based on the company’s real-time analysis of billions of email messages globally each week. Highlights include:
 
” Spam with PDF attachments was initiated at the end of the second quarter. During one massive attack, PDF-spam comprised 10-15% of global spam messages during a 24-hour period, increasing overall global spam traffic by 30-40%
” Spam and viruses have joined forces, using the same botnets to distribute both types of email-borne threats, sometimes even in the same email message
” Global spam levels remained high; 85-90% of all global email is spam
” Over 60% of spam-sending bots also send malware
” Over 300,000 zombies become newly activated each day
” Image spam in Q2 dropped to less than 15% of all spam, compared to 30% in the first quarter of 2007

Spammers unveiled a new email tactic toward the end of the quarter: PDF spam. This type of spam aims to evade anti-spam filters by disguising itself in a common format: attachments of the familiar Portable Document Format files. This trick helps the junk message pass many anti-spam solutions since it looks like a legitimate email.
 
More details, including samples of PDF spam and spam messages containing malware, are available in the Commtouch Q2 2007 Email Threats Trends Report