Rising threat from PDF and ZIP spam, phishing on the increase again

Data collected by SonicWALL’s Smart Network database of over 1.3 million e-mail users shows ongoing growth in the volume of spam, virus and phishing attacks, increased use of PDF spam and the emergence of a new wave of Excel and ZIP spam. The results were based on aggregated results from the SonicWALL Smart Network from April to July, 2007.

SonicWALL’s analysis shows that Directory Harvest Attacks (DHA), Denial of Service (DoS) and similar attacks decreased by 2% over the quarter, but still accounted for 55.7% of e-mail flowing into inboxes. Spam, viruses and phishing attacks, increased by 4% from Q1 2007, and comprised 37.4% of all e-mail, with the remaining 6.9% being Good e-mail — a 3% increase over Q1 2007.

During the second quarter of 2007, PDF spam emerged as a persistent threat. These types of e-mail attacks typically contain little to no text in the body but attach a PDF file, usually a stock or drug spam message containing malicious code, which, if opened, can be automatically downloaded onto a victim’ s computer.

Recently, SonicWALL has detected an increasing amount of Excel and ZIP file spam. Utilizing the same trust-busting premise as PDF spam, Excel and ZIP spam succeed because they mimic legitimate correspondence to get more eyes to view the message.