Two British men who pleaded guilty to charges they helped create the "TK worm" were sentenced to prison Friday in Newcastle Crown Court. The worm infected thousands of computers, including two owned by the U.S. Department of Defense (DOD).

Jordan Bradley, a 22-year-old electrician, was sentenced to three months imprisonment and Andrew Harvey received six months, according to the National Hi-Tech Crime Unit (NHTCU). Harvey is 23 years old and unemployed. Both men were part of the international hacking gang called the Thr34t Krew (TK).

They were arrested in February 2003 after an investigation by the NHTCU and the U.S. Computer and Technology Crime Hi-Tech Response Team (CATCH), based in southern California.

The TK worm created by the gang installed a Trojan horse program and allowed the gang to control infected machines. U.S. authorities said in May that at least two DOD computers were infected.

The sentencing judge said the number of computers compromised was unquantifiable, but U.K. authorities said in 2003 the worm infected as many as 18,000 computers worldwide, causing an estimated £5.5 million (AU$12.66 million) in damages.

Once the computers were infected, the gang could send them commands. Those commands included scanning other computers for vulnerabilities to distributed denial of service attacks, NHTCU said.

A U.S. man, Raymond Paul Steigerwalt, was sentenced to 21 months in prison in May in connection with the Thr34t Krew, and ordered to pay US$12,000 in restitution to the DOD. Steigerwalt, 21, was charged with one count of conspiracy to commit fraud and one count of possession of child pornography.