Botnets cranked out more spam and larger individual files containing spam in the first quarter of this year, according to the latest report from Postini, Google's e-mail filtering and security service.

Despite the best efforts of security software developers and the mostly successful efforts to neutralize especially destructive botnets, such as Mariposa, Zeus and Waledac, Google's data centers reported a 30 percent increase in the size of individual spam messages at the end of March.

"This recent spate of botnet takedowns has not had a dramatic impact on spam levels," Gopal Shah, a member of Google's Postini services team, wrote in a blog posting.


"Although spam and virus levels did fall below Q409 highs, reports from Google's global analytics show that spam levels held relatively steady over the course" of the first quarter, he added.

The spike in malware during the first quarter appears especially acute mainly because hackers and scamsters were very proficient during the first half of 2009, delivering a 3.7 percent increase in virus-laden spam in the first half of the year compared to just a 0.3 percent jump in the last six months of 2009.

Regardless, the proliferation of botnets based in the U.S. and abroad continues at a record pace, infecting millions of PCs, mobile devices and network systems on a monthly basis.

"There's no shortage of botnets out there for spammers to use," Shah said. "If one botnet goes offline, spammers simply buy, rent, or deploy another, making it difficult for the anti-spam community to make significant inroads in the fight against spam with individual botnet takedowns."

The report also found that there's been a resurgence in image spam, mainly a byproduct of the sharing of image templates that makes it easier and faster for spammers to initiate new malware campaigns.

The first quarter also saw a predictable increase in new campaigns piggybacking on breaking news, such as the devastating earthquake in Haiti, as well as the usual garden-variety attacks using celebrity news, cheap pharmaceuticals and social networks to entice new victims to click on spam-spewing links and attachments.

And at the same time that many companies are rapidly accelerating their cloud computing projects to reduce costs and improve efficiency, spammers are stepping up their own spam activities to take advantage of this fundamental shift in enterprise computing.

"The spammers that take advantage of these botnets are a highly active and adaptable group," Shah said. "This is evidenced by the varied techniques and tactics that they employ in an ongoing effort to evade spam filters and deliver messages to their targets."

Larry Barrett is a senior editor at InternetNews.com, the news service of Internet.com, the network for technology professionals.