A systems auditor working on the computer security at the US Department of Education has been jailed for five months for putting spyware on his boss's computer.

Kenneth Kwak admitted putting the malware on his boss's machine that allowed him to monitor emails and internet activity. He then told others in his office about his boss's habits.

"The US government has adopted a 'zero tolerance' policy regarding intrusions into its computer systems, and a clear message is being sent out to its staff that hacks like this are not just unacceptable but criminal," said Graham Cluley, senior technology consultant at Sophos.

"Kwak should be thankful that no evidence was found that his hack was financially motivated, as that surely saved him from a stiffer jail term."

At the end of his five-month sentence Kwak will spend another five months electronically tagged. He will be on probation for three years and has to pay $40,000 restitution to the US government.

Kwak had been facing a maximum sentence of five years in prison and a $250,000 fine.