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Not your father's botnet

Tenacious D

The other recent arrival on the botnet scene is Mega-D. It was discovered by security firm Marshall, which last week said it had dethroned Storm as the top source of spam.

Some of Marshall's peers in the research community aren't so sure about that, including Joe Stewart of SecureWorks. He says Mega-D consists of about 35,000 bots, less than half the size of Storm. Mega-D isn't propagating as fast or efficiently is Storm has, either. Finally, he suspects spam from Storm is being under-counted.

Referring to Mega-D he says: "This is a very strong botnet, but hardly a challenger to Storm."

Nonetheless, Mega-D boasts some advances that Stewart says aren't common in botnets. One of them allows it to avoid being "greylisted," a technique used by email servers to prevent spam by instructing unrecognized senders to retransmit the email later. Whereas most spam bots give up, Mega-D bots don't.

"This is the first time I've seen any bot have any type of code in it dealing with greylisting," Stewart says. "This is actually at the bot level."

Stewart says Mega-D is the work of Russian hackers and has its genesis in a little-known family of malware known as "Ozkok." It is detected by most anti-virus products, but usually is only flagged with generic labels such as "Pakes" or "Agent," which may partly explain why Mega-D has been able to grow into such a large army with seemingly no one noticing.

While the newcomers aren't as big as Storm and, depending on who's asked, aren't believed to be as big of a nuisance, they are a reminder that the development of malware is a growing business that places a high value on innovation. MayDay's ability to communicate within heavily fortified businesses shouldn't be taken lightly. Neither is Mega-D's anti-greylisting capability.

In its first year, Storm showed a preternatural ability to stop on a dime, morph and take on new capabilities. Here's wondering how soon its developers adopt some of these latest bells and whistles? ®

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