Spammersare losing the fight as IT
users become wise to unsolicited files, security software
houseBitDefenderhas said.
BitDefender's researchers said the number of
spam messages with PDF attachments dropped recently. This is
because recipients are not clicking on uninvited PDFs, said Vlad
Valceanu, head of BitDefender's anti-spam lab.
BitDefender rival
MessageLabs
said two weeks ago that
hackers had tweaked the Storm worm to produce the infected PDF
files. These took the form of fake job advertisements, greetings
cards, and stock tips to support penny-stock
"pump-and-dump"
schemes.
Some user companies worried that text-based
anti-spam software could not filter such content accurately,
and blocking PDF attachments was not an option.
"While spammers are sending out fewer attachments with their
e-mails, we do not expect to see a dramatic decrease in the overall
amount of spam distributed," said Valceanu. "Our research has
simply found that spammers are finding newer, more productive
methods in their delivery of spam messages."