PDF spam tsunami hits email inboxes

An aggressive spam campaign designed to ramp up the share price of a convenience store firm led to a 30 per cent increase in the volume of spam circulating across the net at its peak on Tuesday, according to net security firm Sophos.

The junk mail messages, containing an attached PDF file, urge recipients to buy shares in a a firm called Prime Time Group Inc, which markets wireless products to young people, as well as running a number of convenience stores. It's a typical pump-and-dump scam, albeit on a massive scale.

Sophos's spam traps across the world have intercepted examples of junk mails - which focus on the firm's plans open two new stores in Puerto Rico.

The massive spike in spam was first witnessed at Sophos's spamtraps in Germany at 16:40 BST on Tuesday 7 August, but was quickly seen arriving at other monitoring stations around the world. The email messages are being sent from compromised home PCs, turned into zombie relay stations by hackers.

Shares in Prime Time Group rose 60 per cent on the back of the junk mail campaign. There is nothing to suggest that the firm itself is involved. Prime Time Group has launched an investigation aimed at identifying whoever is selling its stock short in the hope of making a quick (possibly fraudulent) buck.

Pump-and-dump scams are email campaigns that seek to encourage armchair investors to sink their cash into a particular firm's stock. The goal is to quickly inflate interest in low-value stock with bogus insider info in order to ramp up share prices, then sell at a profit before the inevitable crash and burn. Meanwhile, those taken in by the ruse are left holding virtually worthless shares.

Earlier this year, the US Securities and Exchange Commission (SEC) had suspended trading in 35 companies as they were found to be commonly referenced in pump-and-dump stock email campaigns.

Pump-and-dump stock campaigns currently account for approximately 25 percent of the world's spam, according to Sophos. But, it said the Prime Time spam campaign is on a different level.

"The scale of this stock pump-and-dump spam campaign is like nothing we've seen before, and it looks as though it is working for the cybercriminals behind it. The share price in this company has rocketed as a result of bogus news being blasted to internet users worldwide," said Graham Cluley, senior technology consultant for Sophos.

The use of PDF files to carry spam messages is an attempt to get past basic anti-spam defences, he added. ®