A grand jury indictment unsealed on Thursday against a 23-year-old American man highlights the extent to which U.S. government computer networks are under siege.

Andrew James Miller, of Devon, Pennsylvania, was arrested on Thursday morning on charges that he tried to sell secret access to two U.S. government supercomputers for US$50,000 to an undercover FBI agent.

The supercomputers belong to the National Energy Research Scientific Computing Center (NERSC), which provides high-performance computing for research projects approved by the Department of Energy.

Its computers are some of the most powerful in the world, such as the "Hopper," a Cray XE6 that ranked #5 in a list of the top 500 supercomputers in the world in 2010, and Carver, described as an IBM iDataPlex Linux cluster with 3,200 compute cores.

By its own admission, NERSC is a ripe target for hackers. "Both because of our unique computing resources, and simply because we are a government institution, attackers target NERSC systems. In particular, smart attackers who have time and resources have been known to target our systems," according to the organization's website.

NERSC supports some 4,000 user-accounts within the U.S. and internationally. But users are not supposed to store classified or national security related information, including any nuclear weapons-related data.

The indictment said that Miller and an as-of-yet unindicted co-conspirator nicknamed "Intel" chatted online with an undercover FBI agent on April 16, 2011. The two were part of a hacking group known as the "Underground Intelligence Agency."

Miller allegedly "stated that he accessed, earlier in the morning, two government super computers associated with the 'nersc.gov' domain," the indictment reads. He also allegedly stated that he installed a backdoor that allowed him to consistently access several government networks.

"Miller then pasted a network notification banner and file system information into the chat to demonstrate his access to nersc.gov," according to the indictment.

Less than a week later, Miller is alleged to have said that he and his partner had access to half of the top 500 supercomputers, possessing some "root" access and other access credentials, mostly on ".gov" and ".edu" domains. In July, Miller "offered to sell" to the undercover FBI agent login credentials to nersc.gov for US$50,000, the indictment said.

NERSC warns on its website that theft of user credentials is its "single greatest threat." The institution uses an intrusion detection system called "Bro" which collects data from a modified version of (SSH) Secure Shell, an encrypted network protocol used for logging into a remote network. SSH is used to log into NERSC's computational systems.

Miller is accused of also installing backdoors, or programs that maintain persistent access, and obtaining login credentials for other organizations including RNKTel.com, a service provider in Massachusetts; the University of Massachusetts-Amherst; and Crispin Porter and Bogusky (CPB Group), an advertising agency in Denver.

In the case of CPB Group, Miller is accused of gaining access to two databases and a mail server. The company's network contains databases for "many large, national databases," the indictment said. The FBI wired $1,000 to Miller via Western Union for the data.

Miller is charged with conspiracy, two counts of computer fraud and access device fraud in U.S. District Court in Massachusetts. If convicted on all counts, he could face up to 30 years in prison, the Department of Justice said.

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