As spam filters become more sophisticated in identifying spam emails, spammers have to think of new and innovative ways to get their emails past the filters. At first, it looked like the giant leap for spammers had to do with their use of images, but that does not seem to be the case anymore. Their next step? PDF files, which seems like a smart move to bypass spam filters. Especially in the work environment, people seem to put more value on PDF files compared to traditional document files such as DOC or TXT. It will be interesting to see not only how well this works, but how quickly algorithms will be developed to block this new method of spamming.

Foiled by increasingly accurate corporate spam filters, spammers have dumped pictures for PDFs in their bulk e-mailings, according to the latest data from security firms.

Image spam, which at the beginning of the year accounted for nearly 60 percent of all junk e-mail, has plummeted and now accounts for only about 15 percent of spam. Taking its place, the number of junk e-mail messages using an attachment in the Portable Document Format (PDF) has steadily climbed since mid-June, accounting for as much as a third of spam.

“It went from zero to — when the spammers started experimenting — fifty-fifty image spam and PDF spam,” said Matt Sergeant, senior antispam technologist for e-mail security firm MessageLabs. “Now, its gone to wholesale PDF spam.”[more]

Tags: Spam