FBI sought approval to use spyware against terror suspects

Reality Bites

Would-be terrorists need only use Ubuntu Linux to avoid the ploy. And even if they stuck with Windows their anti-virus software might detect the malware. Anti-virus firms that accede to law enforcement demands to turn a blind eye to state-sanctioned malware risk undermining trust in their software, as evidenced by the fuss created when similar plans for a "Magic Lantern" Trojan for law enforcement surfaced in the US some years ago.

Graham Cluley, senior technology consultant at Sophos, said that its policy remained that it not give "special treatment" to malware written by the authorities.

"If CIPAV came into our labs we would add detection. The software would be unlikely to have a 'copywriter FBI' notice on it so it may be that we already detect it," Cluley told El Reg.

A seminal academic paper written by Fred Cohen in 1984 showed that it was mathematically impossible to write something that was undetectable, or by similar reasoning, to write a perfect antivirus scanner. Faced with that possibility law enforcement officials would have little option but to request security vendors to deliberately ignore their spyware, an approach Sophos reckons is unworkable.

"If a customer suspects they may be under surveillance and sends a Trojan horse to us, we're going to provide protection against it. We have no way of knowing if it was written by the German or US authorities and, even if we did, we wouldn't know whether it was being used by the police or if it had been commandeered by a third party wishing to spy on our customer," Cluley explained.

The picture gets even more complex if different nations develop their own law enforcement snooping software.

Cluley went on: "The Americans could theoretically write a piece of spyware to spy on criminals in its country and ask us not to detect it. The French may then ask us to detect the American spyware (in case the Americans use it against them). Who should we obey?"

"Security vendors can't play favourites," he added.

It would only require one security vendor (or indeed individual) to write a program which detects the authority's spyware and the idea of convincing the world to turn a blind eye to detecting would fall down like a house of cards, Cluley concluded.

Tapping a phone line and installing malicious code on a user's computer are sometimes compared as equivalent but important differences exist, according to Cluley. "Malicious code on a user's computer can be copied, archived, adapted and - potentially - used by people who do not work for the authorities to spy on completely innocent victims," he explained. ®