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13 Feb 2006

Man accused of hospital zombie attack that brought down computers

The hospital's computer network is alleged to have been disrupted by the botnet infection.

Experts at SophosLabs™, Sophos's global network of virus, spyware and spam analysis center, have reminded organizations of the threat posed by zombie networks after the news that a man has been indicted for a computer attack which is alleged to have jeopardised patient care.

Christopher Maxwell, from Vacaville, California, has been indicted on charges that he launched an attack in January 2005 which struck hard at Northwest Hospital and Medical Center in north Seattle. The attack is said to have shut down computers in the facility's intensive care unit and prevented doctors' pagers from working properly.

When it noticed that 150 of its 1,100 computers were infected, officials at Northwest Hospital contacted the FBI, and put backup measures in place. Nurses are said to have run charts down hallways rather than transferring them electronically.

According to the US Attorney's office in Seattle, 20-year-old Christopher Maxwell first compromised computer networks at California State University, the University of Michigan and the University of California-Los Angeles by exploiting loopholes in their security. Compromised computers were converted into a network of zombie computers (also known as a botnet) which could be remotely controlled for the purposes of planting commission-earning adware.

In total, Maxwell and two un-named youths are said to have created a zombie network of over 13,000 compromised computers. Maxwell is alleged to have fraudulently earned $100,000 from unnamed companies whose adware he installed.

"Although no patients were harmed, any attack against a hospital network is a serious offense," said Graham Cluley, senior technology consultant for Sophos. "All organizations need to put the appropriate resources in place to ensure their computers are not part of a zombie network. Every PC should be properly defended by up-to-date anti-virus software, firewalls, and the latest security patches."

Maxwell has been summoned to appear at the US District Court in Seattle on 23 February. If convicted, the 20-year-old faces up to 10 years in prison and a $250,000 fine. He could also be ordered to pay restitution to Northwest Hospital that estimates its repair bill amounted to $149,000. The two unidentified juvenile co-conspirators are also being prosecuted.

Zombie computers - are your PCs under someone else's control?

Zombie computers can be used by criminal hackers to launch distributed denial-of-service attacks, spread spam messages or to steal confidential information. SophosLabs estimates that more than 60 percent of all spam today originates from zombie computers. In May, the Sober-Q Trojan horse and Sober-N worm worked in tandem to infect and hijack computers around the world, programming them to spew out German nationalistic spam during an election.

As spammers become more aggressive, collaborating with virus writers to create armies of zombie computers, legitimate organizations with hijacked computers are being identified as a source of spam. This not only harms the organization's reputation, but can also cause the company's email to be blocked by others.

Sophos ZombieAlert™ advises service subscribers when any computer on their network is found to have sent spam to Sophos's extensive global network of spam traps, and provides rapid notification to customers if their Internet Protocol (IP) addresses are listed in public Domain Name Server Block Lists (DNSBL). This information helps customers locate, disinfect, and protect these systems from future attacks.

Sophos continues to recommend that computer users ensure their anti-virus software is up-to-date, and that companies protect themselves with a consolidated solution which can defend them from the threats of both spam and viruses.

About Sophos

More than 100 million users in 150 countries rely on Sophos as the best protection against complex threats and data loss. Sophos is committed to providing complete security solutions that are simple to deploy, manage, and use and that deliver the industry's lowest total cost of ownership. Sophos offers award-winning encryption, endpoint security, web, email, mobile and network security solutions backed by SophosLabs - a global network of threat intelligence centers.

Sophos is headquartered in Boston, US and Oxford, UK. More information is available at