McAfee's threat report for the fourth quarter of 2009 highlighted a drop in spam, although the year ended with overall amounts rising.
Spam levels in the last quarter of the year dropped from a record 175 billion a day in the third quarter to 135 billion, a decline of 24 per cent. However, the levels rose again as spammers looked to scoop last minute shoppers.
"Even though we saw a decline this quarter, the overall historical trend still points upward. Compared with the fourth quarter of 2008, volume is up 35 per cent," the report said.
Around 135.5 billion spam emails were sent every day in 2009, compared with 122 billion a day in 2008 and 76.5 billion a day in 2007.
The US still leads in the production of spam, but by a greatly reduced margin. The country accounted for over a third of all spam at the start of 2009, but this had fallen to 16 per cent by the fourth quarter, ahead of Brazil and India.
Overall malware threats continued to rise, according to the report, nearly doubling over the year.
"2009 was a transformative and evolutionary year for computer threats. Aside from the sheer increase in volume, more and more of these threats were internet based, including web site-driven/based attacks and Web 2.0 attacks," said McAfee.
"We also saw portable storage device threats at an all-time high, as well as rogue security software that has truly got out of control."
The amount of malware aimed at USB storage devices rocketed in 2009, in part due to the popularity of the hardware but also because so many PCs use the Windows autorun feature which means that no user action is required to become infected.
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