After a Christmas hiatus, spammers have gone back to work with renewed energy, security researchers said.
During the Christmas season, spam volumes plummeted, falling to just 25 per cent of the August 2010 levels. But spammers are now back at work, said experts.
"The numbers aren't back up to the levels prior to the drop, but they are increasing," Patrik Runald, a senior manager of security research at Websense, said in an interview Monday. Websense spotted a new spike in spam that started early on Jan. 10.
Other security and anti-spam vendors, including Symantec and Commtouch have seen the same. Symantec attributed the increase in spam to the return to work by Rustock, a large botnet responsible during 2010 for a big part of the world's junk e-mail.
Around midnight London time Monday, Rustock again started spamming, said researchers with Symantec Hosted Service's group, which operates MessageLabs, the anti-spam service Symantec acquired in 2008.
"Rustock has resumed activity, and appears set to continue where it left off on December 25 as the biggest source of global spam," said a pair of analysts in a Monday post on the Symantec site.
For lack of any better information, several Rustock experts speculated that the botnet's operators may have simply taken a vacation. "We cannot confirm if the infrastructure is down, being sink holed, or [if] the folks behind it are just taking a break," said Joe Stewart, a researcher at Atlanta-based SecureWorks.
"It looks like they took a vacation, believe it or not," added Runald.
When spam volume plunged late last year, some took it decline as a sign that e-mail spam -- the traditional venue -- was on its last legs and would soon vanish.
"As long as there's money to be made [by spamming], it will not go away," said Runald of e-mail pitches.
Runald also pointed out that previous spam drops had quickly rebounded, citing several "take-downs" of spammer command-and-control servers, including 2008's McColo event , when the hosting company by the same name was disconnected from the Internet. McColo hosted some of the biggest spam botnets, including Rustock. Pulling the plug on McColo sent spam numbers tumbling temporarily by more than 40%.
Interestingly, spam conducted through social networking services, primarily Facebook, did not wane during the holidays, said Runald. That's a good clue that social network spam has become an important new weapon in the spammer arsenal.
"Spam is all social engineering driven," Runald pointed out. "But the success of spam on Facebook is four or five times that of e-mail spam because it's coming from a friend or a friend of a friend."
The lack of a corresponding decline in social network spam during December led Runald to think that there are different groups specializing in different types of spam.
"So last month's drop was not a move from e-mail to social networking, as some reported," said Runald. "Social network spam is an addition to e-mail, not a replacement. E-mail spam won't disappear until e-mail fundamentally changes, but that will never happen."
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is [email protected] .
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