Cookies cause concern in MI5 laptop theft

A laptop computer containing sensitive information on Northern Ireland has been stolen from an MI5 intelligence agent, it emerged today as security experts warned that not all the information on the device was necessarily secure.

The £2,000 computer was snatched from the Security Service worker as he stopped to help a passer-by in the ticket hall at Paddington Underground station in central London.

The MI5 man, along with two other people, chased after the thief as he ran through crowds at the busy station but failed to catch him before he disappeared into a maze of corridors.

The laptop, which was carrying coded information on Ulster, was stolen on the afternoon of 4 March. Jack Straw, the Home Secretary, was told of the security breach.

A government source confirmed the theft and said: "We believe that the information on the laptop is secure. The police are currently investigating the theft."

"We believe this was an opportunistic theft and that the MI5 agent was not targeted deliberately. The information in the computer does not constitute a threat to national security or individuals," he asserted.

The source confirmed that the laptop contained information about Northern Ireland, but said that the information "did not relate to the peace process or security."

Richard Stagg, senior security architect at Information Risk Management, said: "There will be an encryption system on the laptop. It's an accepted fact that occasionally laptops will be stolen, and this is a case of due diligence on the part of MI5 being put to use."

Stagg said that although every laptop from MI5 would have encryption built in, it was still possible that information contained in cookies and in swap files would be present on the PC in an unencrypted form.

Graham Cluley of Sophos said there was a question over whether the whole hard disk was encrypted. Some disk encryption products create a partition on which encrypted files are placed, and this technique leaves some files in plain text.

Special Branch officers and the British Transport Police are investigating the theft.