Military and intelligence organizations have spent a lot of resources guarding against the possibility of hardware trojans, unauthorized modifications to hardware circuits that leak information or impair device functionality. However, I'm not aware of a single confirmed case appearing in the wild.

I've found one reference to radar failure in Syria, but I don't know if that was actually a hardware trojan.

Does anyone know of any cases?

  • So it seems all we have are claims by government officials that it has happened, but no unambiguous examples except possibly Crypto AG although even that isn't certain. Apr 6, 2012 at 5:16
  • So it seems all we have are claims by government officials that it has happened, but no unambiguous examples except possibly Crypto AG although even that isn't certain. The other examples mentioned were firmware backdoors. I was looking for IC level backdoors such as what the Trusted Integrated Circuit program is trying to prevent. But now that I think of it, attaching a hardware keylogger to a keyboard is an example of what I was looking for. I probably overlooked it because hardware trojans are a far out topic, but hardware keyloggers are everyday fare. Apr 6, 2012 at 5:21

4 Answers 4


In addition to the excellent answers given here, the following two articles may be relevant as well:

Old Trick Threatens the Newest Weapons. John Markoff, New York Times, October 26, 2009. (Discusses risks of hardware trojans. Quotes from a White House review which found that there had been several incidents of compromise of hardware, but provides no details. Discusses Crypto AG, a manufacturer of crypto gear, which introduced a backdoor into their crypto hardware at the request of the NSA. Mentions other cases.)

The Hunt for the Kill Switch. Sally Adee, IEEE Spectrum, May 2008. (Discusses the risk of hardware Trojans. Mentions speculation that Israel introduced backdoors into a Syrian radar site, which allowed them to bomb a Syrian military facility without being detected by the air defense radar.)

To learn more about the remarkable Crypto AG story, you can read at Wikipedia, the Baltimore Sun, reporter Wayne Madsen, and elsewhere.


Perhaps this one about a Siberian pipeline, but I'm sure it fits in the "hardware trojan" you're asking for.


Does hardware backdoors also fits your search? If so, some more few examples:

And I was unable to find links to the information I gave below, so I'm leaving it as it is, but I can't remember the source or find it again.

Onde I read something about US selling a faulty DEC chip, which would give wrong math, to the Russians, using some canadian company. I'm unable to find any page about it, I'll keep searching.


Yes, the British and rest of the allies sold several copies of various German enigma machines after the war to developing countries for secure diplomatic cables knowing fore well they could break them (this one is well documented).

Also rumored is that the NSA clipper chip had certain abilities too but this one is only a rumor, though we know it has some major weaknesses (we can't be sure any of them are deliberate).


In Oct 2018, an attack by Chinese spies reached almost 30 U.S. companies, including Amazon and Apple, by compromising America’s technology supply chain, according to extensive interviews with government and corporate sources.

  • 2
    There is some question of this story after several of the parties allegedly involved have given complete denials.
    – Hector
    Oct 11, 2018 at 10:19

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