Heavy Spamming of PDF Malware in October

PDF malware was the most prevalent threat in October 2007, a security company reported on November 1, 2007. Sophos said the most widely spammed malware has been the latest PDFex Trojan that spread trough e-mails carrying infected PDF attachment. The Trojan is now occupying the third place in the virus chart.

PDFex started making the rounds in the end of October 2007; however, it managed to be responsible for 13% of total infected e-mails in October 2007. Its circulation through spam mails was most heavy during October 26 to 28, 2007. And it was found to be responsible for 66% of the total malware that disseminated via e-mails during that period.

The other higher ranks on the October malware chart went to the Pushdo Trojan in the first place and the Netsky worm in the second place. Sophos also found that the number of spammers using PDF to advertise goods was much less in October 2007 than in the past. In September 2007, Sophos had reported United States as the worst spam relaying nation during July-September 2007.

Sophos notes that businesses have been using PDF since long as a medium to share information, therefore, the use of PDF as a social engineering tactic exposes unprotected businesses to risk.

At Sophos again, Senior Security Consultant Carole Theriault said that after Adobe released a patch for its Acrobat program to repair its flaw, people are looking forward to Microsoft to develop a patch for the existing vulnerabilities in Windows that affect other weak applications like Firefox and Skype. Vnunet published this in news on November 1, 2007.

Albeit criminals are now using infected PDF files to target unsuspecting PCs, SophosLabs has not found any evidence of a greater number of spammers continuing to attach PDF files in their unsolicited marketing e-mails to computer users.

Sophos' research further shows that the amount of spam or infected e-mail has come down slightly. In October, e-mails carrying malicious attachment were 1 in every 1,000 while in September 2007, it was one in every 883.

Despite that, Web attacks are still critical threats, warned Sophos.

Related article: HP Users at Risk from Flaws in its Software Update Tool

» SPAMfighter News - 11/17/2007