F-Secure, a Finnish security firm, has warned of a “high volume” of emails containing infected PDF (portable document format) files, a popular format used for sharing documents that contain text and graphics since October 26, 2007.
Many attacks that use infected files attached to an email are picked up before they arrive in the recipient’s Inbox as they contain .exe, or executable files, which once opened install themselves on a PC.
The attacks are different inasmuch as PDF files are normally considered to be safe by most email-filtering technologies, so the emails will get through. PDFs are generally viewed using Adobe’s free Acrobat Reader software.
“We’re worried about this case, as PDF attachments are typically not filtered at email gateways. Executable files are now stripped almost everywhere, but PDF is stripped almost nowhere,” said F-Secure’s chief research officer Mikko Hypponen.
Adobe was aware of the vulnerability in its software several days ago, but as people wouldn’t necessarily use Acrobat Reader every day, they may still be unaware that it needs updating.
“Also, a security update for Acrobat Reader was just made available few days ago, so there are tons of users who haven’t had a chance to update yet,” Hypponen said.
