A rare victory in the spam wars as PDF spam falters

Some promising news on the spam front that no doubt none of you had noticed: spammers evidently have all but given up on the once highly effective gimmick of sending their love cures and get-rich-quick missives via PDF. According to security specialists at Sophos, spam messages sent as a PDF attachment has dropped off the charts in recent weeks. PDF spam had accounted for as much as 30 per cent of all spam at its height earlier this month. Now, it is nearly zero, Sophos reports.

"If PDF spam email messages have all but disappeared, there can only be one reason - they're not working," said Graham Cluley, senior technology consultant for Sophos. Cluley cautions it is too early to tell if PDF spam is gone for good. It took off earlier this month during a single pump-and-dump penny stock campaign for a firm called Prime Time Group Inc., Sophos says. Why the PDF spam, which seemed to be bypassing filters with some degree of regularity, has trailed off is anybody's guess.

Overall spam levels, according to another spam-tracker Postini, have mysteriously trailed off in the past two months to a still mind-boggling 9 billion spam messages intercepted in the past 30 days. Spam volume levels tend to crest and ebb over six-month periods as new gimmicks are tried out and the filters learn to spot them. If PDF spam is truly dead, it's only a matter of time before the spammers will come up with a new innovation to outsmart the filters.