A teenager identified by U.S. law enforcement officials only as B.D.H pleaded guilty last week to charges that he used botnets to illegally install adware on hundreds of thousands of computers in the U.S., including those belonging to the military.

A statement from the U.S. Attorney's office in Los Angeles announcing the teenager's plea calls him a "well-known juvenile member" of the botnet underground. Officials said the teenager pleaded guilty to two counts of juvenile delinquency for conspiring to commit wire fraud, causing damage to computers and for accessing computers without authorization to commit fraud.

The teen is scheduled to be sentenced May 5. Under a plea agreement, he will receive a sentence ranging from one year to 18 months in prison.

Asst. U.S. Attorney Mark Krause said that most of the materials related to the case, including details about the investigation, have been sealed because it involves a juvenile under the age of 18. Krause, however, supplied a redacted version of the charging document against B.D.H, which the courts have allowed to be made public.

According to the public statement and the charging document, B.D.H -- who was known online as "Sobe" -- worked with another person, Jeanson James Ancheta, in a scheme to make money by surreptitiously planting adware on large numbers of computers. Sobe and Ancheta, who was 20 at the time of his arrest in 2006 and from Downey, Calif., first enrolled as affiliates of legitimate online advertising companies so they could obtain affiliate identification numbers so they could get payments for adware installations. But the payments were supposed to be for adware programs installed with the consent of the user.

The two then illegally modified the adware so it could be installed without the user's knowledge or consent and hosted it on servers they controlled.

Between August 2004 and December 2005, Sobe and Ancheta broke into hundreds of thousands of computers and directed them via Internet Relay Channels (IRC) to the adware hosting servers. Once the servers then downloaded the modified adware, Sobe and Ancheta sought compensation from the online advertisers for each installation.

Among the computers infected were those belonging to the Defense Information Security Agency (DISA) and the Sandia National Laboratories.

To avoid getting caught, the two varied the download times and the rate of adware installations on compromised machines. In the charging documents, prosecutors offered numerous examples of chat sessions between Sobe and Ancheta that focused on ways to infect computers and how to avoid detection by network administrators and the FBI.

The chats included discussions on new malware they planned to deploy, as well as methods for disabling systems.

In one of these conversations Sobe noted that it was unlikely that "feds [would] bust in someones (sic) door for irc bots etc. lol", the charging documents showed. Another time, the pair used AIM to troubleshoot a botnet that kept losing bots and could not infect more than 25,000 computers at any given time. During one of these sessions, Sobe was assured that he would earn at least "2.2gs" by the end of the month.

The conversations also showed that both knew that they had infected systems belonging to the Defense Department and to Sandia labs.

Ancheta is now serving a 57-month sentence in a federal prison for his role in the scheme. He was sentenced in May 2006 after pleading guilty to using malicious code to infect thousands of computers and creating vast botnets from the compromised systems. He admitted to selling the botnets to others who used them to launch distributed denial-of-service attacks and for distributing adware.

He also confessed to making US$107,000 in advertising affiliate payments for downloading adware on more than 400,000 infected computers that he controlled.