PDF spam levels drop

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PDF spam appears to be on the wane, with a dramatic decrease in the amount of this type of spam over the last few days, according to researchers at anti-virus firm Sophos.

As reported by IT PRO, levels of PDF spam spiked around the early part of this month. A solitary campaign by spammers to pump up the stock of a company, accounted for a 30 per cent increase in overall junk email levels, but PDF spam now appears to have tailed off.

"If PDF spam messages have all but disappeared, there can only be one reason - they're not working," said Graham Cluley, senior technology consultant at Sophos.

He said that spammers would not turn away from PDF spam if it was an effective way to make money and send users to websites. "This drop indicates that the spammers are finding it hard to fool the public into reading marketing messages distributed in this way."

It is still too early to tell if the fall signalled the demise of PDF spam and more could well be on the way, according to Cluley. But he said that there were good reasons why PDF spam does not have the same effect as image-based spam.

"PDF spam simply isn't as immediate a way of communicating with your intended audience as an instant glimpse of the marketing message in your victim's email preview pane," said Cluley. "Have you tried opening a PDF file? Adobe Acrobat chugs into action, taking a fair while to load before it can show you the contents of the PDF."

He said that consumers learn pretty quickly that it is a waste of time to open every unsolicited PDF they receive, which means "the spammer's message doesn't get read, and the cyber criminals don't make any money."

While PDF spam is waning, Excel spam appears to have taken its place in the form of unsolicited emails bearing attachments with filenames such as invoice20202.xls, stock-information-3572.xls and requested report.xls., according to research carried out by IT security company PineApp.

"Excel spam on its own currently accounts for just five per cent but this still represents millions of messages and next month we may start to see PowerPoint or Word files, for example," said Steve Cornish UK sales and marketing director at PineApp.

"In the last month, image-based spam attacks including PDF and Excel spam accounted for over 50 per cent of all spam we detected."

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