Q1 Malware Report: Server-side polymorphic viruses surge past AV defenses

Throughout the first quarter of 2007, server-side polymorphic malware exploded across email, exploiting the well known zero-hour vulnerability of traditional anti-virus solutions. The Q1 2007: Malware Outbreak Trends, released today by Commtouch, shows how malware writers are using speed, variation and social engineering techniques to mass-distribute their malicious code across the Internet.
 
“The server-side polymorphic distribution pattern has proven a “success’ for malware writers. This method is so adept at evading anti-virus defenses, that it is now being adopted on a large scale,” said Haggai Carmon, Commtouch vice president of products. “By creating a massive number of distinct variants and releasing them in short, intense bursts, virus writers are able to release new variants so quickly that signatures or heuristics cannot be created quickly enough to protect against them all.”  During a peak early in the quarter, the Storm/Nuwar malware released over 7,000 such variants in a single day.
 
Another growing tactic is the increasing utilization of social engineering techniques developed by spammers to help spam slip past email users’ defenses. Malware writers recently began adopting these methods on a large scale to help lure users to open messages and click on attachments. The Storm/Nuwar outbreak in mid-January used tabloid-style email Subjects like “230 dead as storm batters Europe,” “First nuclear act of terrorism!” and “a bouquet of love” to entice readers. In February the Tibs/Zhelatin email-borne malware disguised itself as a friendly Valentine’s Day greeting, coupling affectionate Subject line greetings with docile sounding file names.
 
Sample subject strings:
” 5 reasons i love you
” a song to you
 
Sample file names:
” flash postcard.exe
” greeting card.exe
 
The Nurech malware tries to fool its victims by adding benign sounding file signatures such as “.doc’, “.jpg’ and “.pdf’ before the “.exe’.
 
Sample malware file names:
” rechnung-single.de.doc.exe
” rechnung-singles.jpg.exe
” telekom.pdf.exe
 
To access the Q1 2007 Malware Outbreak Trends report, click here (pdf file).