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Building Backdoors Into Computer Chips

Efforts to introduce malware into computer systems are less precise than building a secret portal right into the architecture.

The Stuxnet worm, a now-famous digital weapon probably aimed at an Iranian nuclear reactor or enrichment plant, turns out to be a ham-handed tool for cyberwarfare. Although it was written to do significant damage to a single facility, with a sophistication that left some analysts breathless, it was anything but precise; it spread promiscuously by USB stick, using flaws in Windows, and wound up on machines from Europe to Indonesia.

Swifter methods of electronic warfare may already exist. The secret Israeli attack on a suspected nuclear plant in Syria near the end of 2007 occurred during a mysterious blackout of Syrian air defenses. A report in 2008 suggested the blackout was the result of Stuxnet-style sabotage using not a computer worm but a purpose-built backdoor in European computer chips.

The technical journal IEEE Spectrum speculated that "commercial off-the-shelf microprocessors in the Syrian radar might have been purposely fabricated with a hidden 'backdoor' inside. By sending a preprogrammed code to those chips, an unknown antagonist had disrupted the chips' function and temporarily blocked the radar."

The journal cited an American source who said French military contractors had built these backdoors into computer chips because "the French wanted a way to disable" any of their circuits that fell into enemy hands.

The capacity to disable a circuit is called a "kill switch." A proper "backdoor" would leave an opening for a foreign government to control a certain system, which (experts assume) was also the purpose of Stuxnet. But undermining a system with a computer chip is much cleaner than sending a worm into the world on a USB stick: It doesn't rely on software bugs, it's all but undetectable, and a chip can't be "cleaned out" like a malware infection. It (or the system that uses it) would have to be replaced.

If the Syrian-sabotage story is true, it's easy to assume that most Western governments have leaned on their high-tech contractors for similar backdoor help. (Could Washington have missed a chance the French have seized? Unlikely.) But it's not all good news for the West, because the decimation of domestic manufacturing in rich nations has seen to it that most computer chips pass under the hands of workers elsewhere, places that have their own agendas. Like, say, China.

Three years ago the German government noticed that "a large number of computers in the German chancellery as well as the foreign, economy and research ministries had been infected with Chinese spy software," according to Spiegel magazine. "Information was taken from German computers on a daily basis by hackers based in the northwestern province of Lanzhou, Canton province and Beijing."

The scandal showed not only that China was keeping up with malware technology, but also that it was fishing for German industrial secrets. It also showed the sheer impossibility of shielding every detail of sensitive technologies in a globalized world economy. And since even a single modern jet fighter can use hundreds or even thousands of microchips, the potential for mayhem is vast.

Nevertheless, this defense nightmare is still a job for governments, rather than the public. And the governments are on it, more or less — the U.S. and its European allies are trying to build "trusted" production lines for military microchips and other complex components.

What the public doesn't have to worry about (for now) is a serious attack on its nuclear power plants through the anarchic, open Internet. The Stuxnet and Syria stories show that real cyberwarfare needs to occur at a deeper level than just a little malware attached to your e-mail. So recent calls for a complete reconstruction of the public Internet in the name of defending against cyber-armageddon are frivolous.

And a separate push to reconfigure the public Internet follows the logic of cyberwarfare itself: The FBI wants Congress to demand wiretapping technologies be built into every form of digital communication in the U.S., from BlackBerry messaging to Skype. "Essentially, officials want Congress to require all services that enable communications ... to be technically capable of complying if served with a wiretap order," according to the New York Times.

This debate may sound familiar to people who remember the "Clipper chip" absurdity of the 1990s. But the more common term for the FBI's desire is — wait for it — a backdoor.