Most prevalent malware threats in October

IT security and control firm Sophos has revealed the most prevalent malware threats and countries causing problems for computer users around the world during October 2007. The study, compiled by Sophos’s global network of monitoring stations, has shown that a new Trojan horse, PDFex, that is typically spammed out in email messages with an infected Adobe Acrobat PDF attachment, has smashed its way into third position in the chart.

The Trojan was widely spammed out in an attack during the last few days of October, taking advantage of an unpatched Windows vulnerability to infect innocent PCs.

Although criminals are currently using PDF files to try and infect innocent PCs with malware, SophosLabs has seen little evidence of more spammers continuing to use PDF files to get their unwanted marketing messages in front of computer users.

Sophos’s research also indicates a slight decrease in the percentage of infected email. Overall in October, 0.1 percent of emails were carrying malicious email attachments, or one in every 1,000, compared to 1 in every 833 during September.

Web attacks continue to pose a significant threat, with Mal/Iframe being responsible for almost seven out of every ten infections found on the web by Sophos. During October, Sophos detected an average of 5,200 new compromised webpages hosting malicious code each day, a similar figure to last month.

Troj/Unif is a new entry at number two this month, accounting for 15 percent of all infected webpages. It was used by hackers in a number of coordinated attacks during October, where legitimate webpages were compromised and visitors were subsequently redirected to a series of attack sites, hosted in countries all over the world, from Turkey to Malaysia.