“Hackers are using it to trick users into running malicious code and opening the backdoor of the network to vulnerabilities. The steady increase in the volume of spam seen traveling across the net is directly related to the enormous rise in Stratio worm strains in recent months.”
Along with the potential for more and varied criminal activity including cyber-extortion, spam today is increasingly made up of Word documents and images. A trend Sophos also identified on Monday.
This is bogging down the Internet as a whole and making corporate communication via email more and more expensive to manage and maintain.
“The character of this has changed quite a bit in the last year. Something called image spam and document spam has exploded,” said Druker. “Typically those are stock pumping schemes or phishing schemes … that’s up from minimal last year to 30% of all traffic today.”
Hackers now use techniques such as re-arranging as many as 25 tiny images into a message in an HTML email or using animated GIF attachments to bypass optical character recognition technology in an effort to bypass email security systems. Infected computers are now also re-trying temporarily blocked email connections just like real mail servers do.