The volume of junk e-mail sent worldwide plummeted on Tuesday after a company providing the servers for the spammers was taken offline.

The bad guys install malware on computers that they can control in vast networks, primarily to send spam for counterfeit pharmaceuticals and designer goods, fake security products and child pornography. Approximately 190 billion spam messages are sent every day from more than 1.5 million hijacked computers. The spammers set up servers to control the hijacked computers and to display web pages offering illicit goods for sale.

The spammers don’t buy their own servers. They buy server space from hosting companies, which are shielded from liability in many cases and not directly responsible for the actions of their customers. That has made it difficult to find the spammers and prosecute them, leaving law enforcement frustrated and frequently ineffective.

Reports were published recently identifying McColo Corp., a San Jose company, as the hosting company of choice for virtually all the top botnets blasting out spam or malware attacks. The company has offices in a 30-story office tower in downtown San Jose and apparently its entire business is devoted to providing a platform for bad guys and diverting any attempt to pursue the spammers by refusing to cooperate with law enforcement and shifting the spam networks around to help them evade detection. Researchers estimated that networks run through McColo servers were responsible for 75% of the world’s spam.

In an interesting twist, security researchers contacted the two companies providing the Internet connection to the building. Both companies became convinced that McColo Corp. was evil and decided to cut off the company’s Internet connections on Tuesday without fuss or delay.

The volume of spam worldwide dropped by more than forty percent immediately.

Spam drop

Lots of companies monitor spam and all of them noticed the huge decline, with estimates of drops in global spam from 40%-75% when McColo was forced offline.

This won’t permanently reduce the volume of spam. It won’t take long for McColo to find other Internet connections or for other companies to step up in its place. Trying to shut down the bad guys is like playing Whack A Mole – a law enforcement victory here, a broken Internet connection there, but they keep popping up.

It’s always nice to have a moment of triumph, though, and this was a particularly dramatic one.

It was reporting by Brian Krebs of the Washington Post that got the carriers’ attention – here’s his article about the effect of the disconnect.

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