Windows 7: Researchers question Microsoft's botnet take-down.

A prominent security researcher today said he doubts Microsoft's take-down of the Waledac botnet would have any impact on spam levels, as the company claimed.

"Waledac just is not a hugely prolific spammer," said Joe Stewart, director of malware analysis at SecureWorks and a noted botnet researcher. "So I don't think it's going to affect spam [volume]. What it does do lately..., what it's used for, is to install rogue antivirus software."

The U.K.-based anti-spam service Spamhaus echoed Stewart today. "If [Microsoft's take-down] did affect spam, we haven't noticed," said Richard Cox, the chief information officer at Spamhaus. Like Stewart, Cox also dismissed Waledac's threat as a spam engine.