Computers in the United States launched the most cyberattacks in 2008, more than doubling the number from any other country, according to data published by SecureWorks, a security-as-a-service provider.

The United States has the most number of compromised computers, many of which are being used to spread malicious attacks, Don Jackson, director of threat intelligence for SecureWorks, told SCMagazineUS.com.

Between January and September 2008, 20.6 million attempted attacks against SecureWorks' clients originated from computers within the United States. The second-highest number of cyberattacks came from China with 7.7 million attempted attacks originating from computers there.

Of countries where compromised computers have launched the most attacks, Brazil came in third, with 166,987 attempted attacks and South Korea followed with 162,289.

“We have a lot of different countries now that have joined the big leagues,” Jackson said.

For organizations to avoid being compromised, SecureWorks recommended utilizing a blacklist to block inbound communications from IP addresses that are known to be malicious and also blocking outbound communications to foreign countries known to harbor hackers and networks known to host criminal activity.

“This should be a warning to organizations and personal computer users that, not only are they putting their computers and networks at risk by not securing them, but they are actually providing these cybercriminals with a platform from which to compromise other computers,” Hunter King, security researcher for SecureWorks, said in a news release.

SecureWorks' data lists countries in which cyberattacks against its clients originated. The numbers indicate attacks coming from compromised computers in each country.