#2 Grum:

Fact: Grum sends 18 billion spam messages per day

Also known as Tedroo and Reddyb, Grum was a botnet involved in sending pharmaceutical spam emails across the globe. Traced back in early 2008, Grum is one of the largest botnets found till date. At the time of its shutdown on July 19, 2012, it was reported that Grum comprised around 18 percent of worldwide spam traffic. Grum relies on two types of control servers for its operation. One type is used to push configuration updates to the infected computers, and the other is used to tell the botnet what spam emails to send.

Grum relies on two types of control servers for its operation. One type is used to push configuration updates to the infected computers, and the other is used to tell the botnet what spam emails to send

In July 2010, the Grum botnet consisted of estimated 560,000–840,000 computers infected with the Grum rootkit. The botnet alone delivered about 39.9 billion spam messages in March 2010, equating to approximately 26 percent of the total global spam volume, temporarily making it the world's then-largest botnet.

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