New Botnet Now Accounts for Half of All Spam

New research from Marshal’s TRACE team has found that the new Srizbi botnet, first detected in February, has now grown to the point that it is now responsible for half of all spam sent. This makes it the world’s largest botnet. The team estimates it is made up of at least 300,000 computers and sends over 60 billion spam messages per day. 60 billion! It’s been used to promote everything from watches to sexual enhancement pills., and also uses spam disguised as celebrity news to distribute its own malware.

While Srizbi grows to mammoth proportions, Storm has begun to fizzle out. Spam sent from it has decreased by over 57%. This caused it to lose its place as the number one source of spam to the Mega-D botnet, which declined in February when it’s controlling servers went offline for 10 days. Unfortunately it’s back now and fighting for second place with the Rustock botnet. To give you an idea of the disparity between the first and second place botnets, Rustock sends merely 60,000 spam messages a day.

“The challenge now is for the security industry to turn its sights on Srizbi and the other major botnets. We look forward to seeing Microsoft target Srizbi with MSRT in the near future,” said Bradley Anstis, vice president of products at Marshal.

Until now Srizbi has been mostly overshadowed by the Storm and Kraken botnets. Kraken had been found in over 50 Fortune 500 companies and was undetectable in most machines, even if they are running up to date anti-virus software. Recently researchers at DV Labs were able to infiltrate it and shut it down, severely impacting its threat.

It’s interesting that Srizbi rose to glory just as Mega-D went offline back in February. Is there a connection? No one knows for sure, but it does seem to be quite the coincidence!