PDF files used to attack computers - security firm

HELSINKI (Reuters) - Emails containing malicious PDF files have been putting computers at risk since Friday, Finnish security software firm F-Secure said on Saturday.

"The emails sent in bulk looked like credit card statements, and contained an attachment called 'report.pdf'," its chief research officer Mikko Hypponen said in a statement.

When such PDF files are viewed on vulnerable machines, they start downloading software from servers in Malaysia or Sweden, which are now being cleaned, he said. "There will be more such attacks."

"We are worried about this case, as PDF attachments are typically not filtered at email gateways."

A security update for Acrobat Reader, which opens PDF files, was made available a few days ago, but many users have not updated the programme yet, Hypponen said.