Global Internet spam levels rose 4.9 per cent in January this year since December 2008 to 74.6 per cent, according to the MessageLabs Intelligence Report. This is the proportion of e-mail that was blocked as spam by the tech firm's e-mail protect services.

Levels were close to those experienced before Internet service provider McColo was taken down in November 2008, said MessageLabs, which is now part of Symantec. MessageLabs Intelligence is a source of data and analysis for messaging security issues, trends and statistics.

Among the top 10 botnets responsible for distributing spam, Mega-D (Ozdoc) had the highest throughput in January, sending more than 26 million spam e-mails per minute.

Cutwail (Pandex) remains the largest botnet with more than one million active IPs this month. Among the top 10 are some new players, including Xarvester, Donbot and Waledac.

"The potential of these botnets to spam in large volumes is a major concern," said Richard Bowman, regional manager of MessageLabs South Asia. "In particular, Waledac is believed to be the next generation of the infamous botnet Storm (Peacomm). While Waledac malware was spread at an alarming rate in January, it was dispersing spam in relatively small volumes. For now, the botnet controllers are clearly focusing on growing and developing this new botnet resource rather than using it to spam. It will be one to watch as 2009 progresses."

More stock spam

With the increase in spam came a resurgence of stock spam. Since the indictment of notorious stock spammer Alan Ralsky in January 2008, this form of spamming has been relatively scarce.

But with the help of CAPTCHA (Completely Automated Public Turing Test to tell Computers and Humans Apart)-breaking tools aimed at major e-mail providers and the shaky economic climate, MessageLabs identified many examples of spam messages sent from legitimate-looking e-mail addresses touting penny stocks. This was an opportunity to hook consumers who may not be able to obtain credit by traditional means with the promise of big returns for little investment.

Other new topics used by spammers this month included the US presidential inauguration. The unrest in the Middle East was also exploited to draw attention to messages which appeared to be used to further the aims of terrorist organisations.