US Ranks First for Bot-Infected Computers and Spam Output

According to data gathered by Microsoft's Malicious Software Removal Tool (MSRT), the United States had the highest number of computers infected with botnet malware, during the first half of 2010.

Botnet are armies of infected computers, which connect to remote command and control (C&C) servers and listen to instructions from attackers.

Botnets can serve a variety of criminal activities, but the largest ones are primarily used to send spam.

According to a recent report from Symantec, during the first half of the year, 90% of the daily spam traffic was generated by five to six million compromised computers.

In the latest edition of its Security Intelligence Report (SIR), Microsoft reveals that during Q2, MSRT has cleaned 2,148,169 bot infections from US computers.

That's four times more than in the second country on the list, Brazil, with 511,002. Spain (485,603), Korea (422,663) and Mexico (364,554) complete the top five.

"Unsurprisingly, the list is dominated by populous locations with large numbers of computer users, led by the United States and Brazil," says Microsoft.

However, there are at least two regions with large numbers of computers that do not dominate the list – China, which finished 8th, and Russia, 9th.

The large number of bot-infected computers in US is also reflected in the country's ranking in spam statistics, where it also first.

According to data from UK-based Sophos, during the last quarter, the United States were responsible for 18.6% of the world's junk mail traffic.

The security vendor releases geographic spam statistics as a "dirty dozen" list of countries, the latest of which reads: USA (18.6%), India (7.6%), Brazil (5.7%), France (5.4%), UK (5.0%), Germany (3.4%), Russia (3.0%), S Korea (3.0%), Vietnam (2.9%), Italy (2.8%), Romania (2.3%) and Spain (1.8%).

Yes, according to Sophos, China is not amongst the world's twelve most spammiest countries, despite Asia accounting for 30.0% of all spam traffic. Now, that's surprising.