More great investigative reporting from Brian Krebs:
An increasing number of services offered in the cybercrime underground allow miscreants to purchase access to hacked computers at specific organizations. For just a few dollars, these services offer the ability to buy your way inside of Fortune 500 company networks.
The service I examined for this post currently is renting access to nearly 17,000 computers worldwide, although almost 300,000 compromised systems have passed through this service since its inception in early 2010.
Read more on Krebs on Security.