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Is Ken Thompson's compiler hack still a threat?

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Re: Is Ken Thompson's compiler hack still a threat?

#21

Post by monochromatic »

taeric wrote: post #19
Scramblejams wrote: post #16

Earlier quoted context omitted.

Did you mean that the compromised printer would be made to produce compromised output? If so, the downvotes may be because it's relatively easy to audit the output of a 3D printer, compared to the output of a compiler. It's a common practice, for example, to x-ray a critical piece of structure to verify it's free of cracks. A similar inspection would generally show if the hidden internals of a printed object conform…

So, the full argument my friends and I were having, was that it would be impossible for a government to enforce printers that could not do guns. My assertion was it was likely more doable than my friend would care to admit. My claim centered on this idea, as well as the identifying marks laserjets do on printouts and a belief that they already have scanners noticing when money is scanned. (No, I don't know the detail…

"Money" is a lot more of a known quantity than "gun." How would they detect a printer making a gun I'd designed myself?

Re: Is Ken Thompson's compiler hack still a threat?

#22

Post by taeric »

monochromatic wrote: post #21
taeric wrote: post #19

Earlier quoted context omitted.

So, the full argument my friends and I were having, was that it would be impossible for a government to enforce printers that could not do guns. My assertion was it was likely more doable than my friend would care to admit. My claim centered on this idea, as well as the identifying marks laserjets do on printouts and a belief that they already have scanners noticing when money is scanned. (No, I don't know the detail…

"Money" is a lot more of a known quantity than "gun." How would they detect a printer making a gun I'd designed myself?

I was thinking more of the common types of gun. Much more likely someone would try and make an AR-15/whatever than a self designed thing.

Again, I wasn't meaning this to be air tight. Just more doable than nothing.

Re: Is Ken Thompson's compiler hack still a threat?

#23

Post by monochromatic »

taeric wrote: post #22
monochromatic wrote: post #21

Earlier quoted context omitted.

"Money" is a lot more of a known quantity than "gun." How would they detect a printer making a gun I'd designed myself?

I was thinking more of the common types of gun. Much more likely someone would try and make an AR-15/whatever than a self designed thing. Again, I wasn't meaning this to be air tight. Just more doable than nothing.

Well, fair enough. If you hard-code in a few of the more common files that contain AR lowers, you'll probably catch 80% of this.

Re: Is Ken Thompson's compiler hack still a threat?

#24

Post by taeric »

monochromatic wrote: post #23
taeric wrote: post #22

Earlier quoted context omitted.

I was thinking more of the common types of gun. Much more likely someone would try and make an AR-15/whatever than a self designed thing. Again, I wasn't meaning this to be air tight. Just more doable than nothing.

Well, fair enough. If you hard-code in a few of the more common files that contain AR lowers, you'll probably catch 80% of this.

Actually, I was thinking more that you could target common ammunition types.

Regardless, I thought it keyed into this idea, because so long as you had it in the printer to make it such that any printer it created also did this, it fits this description perfectly. (And yeah, I realize I just jumped from 3d printer to replicators. My knowledge in this area is as shallow as it seems. :) )

Edit: forgot to add, the idea was originally that the printer would make the gun in such a way that it would be identifiable as coming from that printer. Not that it would have to refuse to make them.

Re: Is Ken Thompson's compiler hack still a threat?

#25

Post by wglb »

michaelhoffman wrote: post #8
wglb wrote: post #6

Earlier quoted context omitted.

And, after he first mentioned the exploit, and before he achieved the award, the AT&T lawyers made him say publicly that he didn't really do that.

Where can we find records of him stating that this never happened?

I am unable to locate it now.

It seemed very weird at the time--the AT&T lawyers making him deny what he had done.

And it is possible that the denial was about the general release of the exploit, rather than whether or not he really did it. My memory could be slightly off for events back that far ago.

It was a minor industry rag and the story was published shortly after the hack was announced. It might have been the same paper that Dennis Ritchie told of auditing the behavior of Coherent and saying publicly that it was definitely not a clone. I think the lawyers were upset about that as well.

Re: Is Ken Thompson's compiler hack still a threat?

#26

Post by wglb »

mseepgood wrote: post #2

Did he really do that?

See the email in the article http://skeptics.stackexchange.com/questions/6386/was-the-c-c...

marked with

From: Ken Thompson Date: Wed, Sep 28, 2011 at 6:27 PM Subject: Re: Was compiler from "Reflections" ever built or distributed? To: Ezra Lalonde

Re: Is Ken Thompson's compiler hack still a threat?

#27

Post by patio11 »

mseebach wrote: post #5

A variation of the threat very much exists: Do you know (meaning, there are no unknown unknowns) that no piece, anywhere in your toolchain (OS, compiler, library, framework, buildtool, CI etc), contains malicious code? At the time Thompson made this comment, he talked about the C compiler because it was the one bit of shared code everything else depended on. Today, the attack surface is much, much larger. If I was ru…

I think you vastly overestimate the difficulty of getting a code execution bug on Rails relative to the resources of a nation-state. You don't need to do anything remotely suspicious; just hire vulnerability researchers. They're ridiculously cheaper than aircraft carriers.

Or, to put it another way, anybody with $20k can uncover an RCE in Rails without needing to suborn any community member.

Re: Is Ken Thompson's compiler hack still a threat?

#28

Post by SkyMarshal »

mseebach wrote: post #5

A variation of the threat very much exists: Do you know (meaning, there are no unknown unknowns) that no piece, anywhere in your toolchain (OS, compiler, library, framework, buildtool, CI etc), contains malicious code? At the time Thompson made this comment, he talked about the C compiler because it was the one bit of shared code everything else depended on. Today, the attack surface is much, much larger. If I was ru…

>I'd target trusted members of the communities around popular open source projects.

I'm sure everyone here is already aware, but the FBI may have already experimented with that:

http://arstechnica.com/information-technology/2010/12/fbi-ac...

Re: Is Ken Thompson's compiler hack still a threat?

#29

Post by tptacek »

patio11 wrote: post #27
mseebach wrote: post #5

A variation of the threat very much exists: Do you know (meaning, there are no unknown unknowns) that no piece, anywhere in your toolchain (OS, compiler, library, framework, buildtool, CI etc), contains malicious code? At the time Thompson made this comment, he talked about the C compiler because it was the one bit of shared code everything else depended on. Today, the attack surface is much, much larger. If I was ru…

I think you vastly overestimate the difficulty of getting a code execution bug on Rails relative to the resources of a nation-state. You don't need to do anything remotely suspicious; just hire vulnerability researchers. They're ridiculously cheaper than aircraft carriers. Or, to put it another way, anybody with $20k can uncover an RCE in Rails without needing to suborn any community member.

$20k is too low, but your point stands.
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