When it comes to cybercrime, Eastern Europe, China, and Brazil may get the lion's share of press attention, but a new study shows a vast proportion of attacks come from computers in the United States.

Security firm SecureWorks has counted 20.6 million attacks against its customers that originated inside US borders so far this year. China ranked No. 2 on the list with 7.7 million, and Brazil and South Korea came in third and fourth, with 166,987 and 162,298 respectively. The study, which was released Monday, is a strong indication that there's no shortage of compromised computers on US soil.

The findings have important implications for organizations trying to fend off denial-of-service attacks and other net-based assaults. Namely, that they need to be aware of the threat that US-based machines pose. In August, after Russia invaded the Republic of Georgia, many Georgian IT staff members sought to secure their networks by blocking Russian IP addresses. They ended up getting clobbered anyway because they failed to block hostile computers from Turkey and the US, said Don Jackson, SecureWorks's director of threat intelligence.

Whereas many of the compromised machines in the US are under the control of people outside of the country, that is not generally the case in China. Entire university networks in that country remain under the control of hackers there, often with the help of insiders. Miscreants in Japan and Poland use much the same approach.

In related news, Chinese hacktivists have begun defacing the websites of several companies involved in the distribution of tainted milk. According to this post on the Dark Visitor blog, targets include the Sanlu Milk Company and the Mongolian Milk Corporation.

"When an infant with kidney stones lies weeping in a hospital bed, can the factory owners intuitively sense the condemnation?" one defacement reads. "In order to gain profit you have gone so far as to devastate these young lives!"

The defacements are designed to protest the shipping of baby formula containing melamine, a toxic chemical used illegally to make the milk appear it has more protein - and hoodwink food testing agencies. ®