From: Ken Thompson <kenbob@gmail.com>
To: Douglas McIlroy <douglas.mcilroy@dartmouth.edu>
Cc: TUHS main list <tuhs@minnie.tuhs.org>
Subject: Re: [TUHS] Thompson trojan put into practice
Date: Mon, 20 Sep 2021 06:51:40 -0700 [thread overview]
Message-ID: <CAMP=X_mmx7EyGbE7-8KLa6piZgZ+Df3dRGcBtBx-=Qy+DFv6PQ@mail.gmail.com> (raw)
In-Reply-To: <CAKH6PiVEHTfmdpz2iPwm1oSoL2r15WGfEU6xAdE60wq0xubWfw@mail.gmail.com>
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pwb recompiled the compiler and it got 1 byte larger.
again, another byte. after that they played with it
until they broke the quine part. i am not sure that
if they ever realized what was going on.
the extra byte was my bug.
On Mon, Sep 20, 2021 at 4:58 AM Douglas McIlroy <
douglas.mcilroy@dartmouth.edu> wrote:
> >> > It's part of my academic project to work on provable compiler
> security.
> >> > I tried to do it according to the "Reflections on Trusting Trust" by
> Ken
> >> > Thompson, not only to show a compiler Trojan horse but also to prove
> that
> >> > we can discover it.
> >>
> >> Of course it can be discovered if you look for it. What was impressive
> about
> >> the folks who got Thompson's compiler at PWB is that they found the
> horse
> >> even though they weren't looking for it.
>
> > I had not heard this story. Can you elaborate, please? My impression
> from having
> > read the paper (a long time ago now) is that Ken did the experiment
> locally only.
>
> Ken did it locally, but a vigilant person at PWB noticed there was an
> experimental
> compiler on the research machine and grabbed it. While they weren't
> looking for
> hidden stuff, they probably were trying to find what was new in the
> compiler. Ken
> may know details about what they had in the way of source and binary.
>
> Doug
>
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next prev parent reply other threads:[~2021-09-20 13:53 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-20 11:57 Douglas McIlroy
2021-09-20 13:51 ` Ken Thompson [this message]
2021-09-20 14:35 ` John P. Linderman
2021-09-20 14:48 ` [TUHS] On UNIX Trojans Ron Natalie
-- strict thread matches above, loose matches on Subject: below --
2021-09-20 3:04 [TUHS] Thompson trojan put into practice Noel Chiappa
2021-09-20 3:21 ` David Arnold
2021-09-20 4:35 ` Earl Baugh
2021-09-20 4:36 ` Earl Baugh
2021-09-20 2:39 Douglas McIlroy
2021-09-20 2:50 ` Larry McVoy
2021-09-20 7:12 ` arnold
2021-09-19 15:46 arnold
2021-09-19 15:58 ` Al Kossow
2021-09-19 16:02 ` arnold
2021-09-19 16:10 ` John Floren
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