I'm glad they mention Wheeler's work briefly in section 7.2, since it provides a general counter to the trusting-trust attack that a lot of people seem to not know about. They dismiss it as not applying in this case, but I'm not really convinced by their argument. It's true if you only replace the compiler and run in the same environment then it won't help, but IIRC Wheeler's approach treats the environment itself as a parameter to diversify on. So not just the compiler, but also the host/OS, and even the hardware. Thus it's trivial to extend it to strip. Build binutils from source with your bad distro toolchain, fixup with your distro strip, call this build A. Then build binutils from source in a diverse environment, which includes fixup with a diverse stripper, call this B. Then do a rebuild (same diverse environment) but with B's toolchain and stripper, call this C, and compare C with A. Mismatch busts the attack.
FYI, x86_64-linux and i686-linux nixpkgs bootstrap seed is not 25 bundled binaries, but 181 bytes, since https://github.com/NixOS/nixpkgs/pull/479322. at publication date this article would apply to non-x86 platforms like aarch64-linux, risvc64-linux, etc.
if you're concerned about this and not on x86, i encourage you to extend this to other platforms! i believe it's possible to generalize this to every linux platform musl itself supports, in time.
> Ken Thompson's trusting-trust attack [...] is widely regarded as a threat specific to compilers. We show that it is not
And yet, from Reflections On Trusting Trust:
> In demonstrating the possibility of this kind of attack, I picked on the C compiler. I could have picked on any program-handling program such as an assembler, a loader, or even hardware microcode.
The paper is certainly a nice worked-out example of the attack, which is worthwhile, but it's not novel.
It goes back to Paul Karger's MULTICS Security Evaluation where he invented and described the attack. Thompson learned it from him. Karger invented a lot of attacks and security techniques a decade or more ahead of the hacking community.
The solution to this in the Orange Book (TCSEC) days in the 1980's-1990's was a system fully traceable from requirements to code, proven to embed a security policy, and analyzable and buildable from source locally by the customer using existing, trusted tools. Eventually, people added hashes for the code and data.
So, your program that combines source files or checks dependencies would be fully specified in its success and failure states. Only combinations of functions leading to a provably-secure state are even allowed. If you can't do that, the feature is too complex to allow. Human pentesters review it from design to algorithms to building it to spot ways attacks might happen.
That's what it takes to build software that usually resists subversion. Most software isn't built that way. It can't be because the priorities of developers and customers work against it. So, we'll continue to see clever attacks that exploit systems not designed to high security standards.
For this topic, I recommend David A. Wheeler's page on Software, Configuration Management Security because it covers many issues with it in mostly-centralized systems.
> Most software isn't built that way. It can't be because the priorities of developers and customers work against it.
The most significant such priority may be cost, of paying developers and of time to delivery.
I've been thinking that the dramatic reductions in those costs due to LLMs enables us to produce much more quantity and/or quality. Many complain now about quantity, so perhaps we are finally at a stage where we don't need much more software, and can focus on quality.
In other words, LLMs might enable us to some of these things that were impossible before.
The Nix project has been able to bootstrap an entire Linux distribution from scratch. However, doing that traditionally relies on binary seeds -- meaning the very first compiler in the chain is downloaded as a prebuilt binary rather than compiled from a fully verified source. This leaves a single foundational gap where users will have to trust trust an external black-box binary. Efforts toward reproducible builds and reducing this trust perimeter focus on removing binary seeds and tracing every compilation step back to a minimal, manually verifiable root.
Ken Thompson's Trusting Trust is an interesting conundrum... there are ways to minimize the need to trust however, if you can express everything in the same language or common runtime:
Yes and no. We used to have rampant script kiddies back in the '90s and early 2000s. After 2005-ish, well maybe 2010, most systems became adequate enough to not trust users' input, bug bounties, security as a separate role, etc, etc.
It would take at least some knowledge to hack, not just a random script from a forum.
Whilst true, security will improve rapidly again. Potentially via AI, potentially via other technologies.
If its easy enough to find exploits, its likely similarly easy to scan code for exploits, or use AI-based anti-virus technologies. The only thing holding us back is the cost of compute. We can't all run the latest models against everything.
I'm glad they mention Wheeler's work briefly in section 7.2, since it provides a general counter to the trusting-trust attack that a lot of people seem to not know about. They dismiss it as not applying in this case, but I'm not really convinced by their argument. It's true if you only replace the compiler and run in the same environment then it won't help, but IIRC Wheeler's approach treats the environment itself as a parameter to diversify on. So not just the compiler, but also the host/OS, and even the hardware. Thus it's trivial to extend it to strip. Build binutils from source with your bad distro toolchain, fixup with your distro strip, call this build A. Then build binutils from source in a diverse environment, which includes fixup with a diverse stripper, call this B. Then do a rebuild (same diverse environment) but with B's toolchain and stripper, call this C, and compare C with A. Mismatch busts the attack.
FYI, x86_64-linux and i686-linux nixpkgs bootstrap seed is not 25 bundled binaries, but 181 bytes, since https://github.com/NixOS/nixpkgs/pull/479322. at publication date this article would apply to non-x86 platforms like aarch64-linux, risvc64-linux, etc.
if you're concerned about this and not on x86, i encourage you to extend this to other platforms! i believe it's possible to generalize this to every linux platform musl itself supports, in time.
This is basically an ELF executable file infecting virus, nothing novel about that.
From TFA:
> Ken Thompson's trusting-trust attack [...] is widely regarded as a threat specific to compilers. We show that it is not
And yet, from Reflections On Trusting Trust:
> In demonstrating the possibility of this kind of attack, I picked on the C compiler. I could have picked on any program-handling program such as an assembler, a loader, or even hardware microcode.
The paper is certainly a nice worked-out example of the attack, which is worthwhile, but it's not novel.
It goes back to Paul Karger's MULTICS Security Evaluation where he invented and described the attack. Thompson learned it from him. Karger invented a lot of attacks and security techniques a decade or more ahead of the hacking community.
https://gwern.net/doc/cs/security/2002-karger.pdf
“Widely regarded” still applies, I think.
The solution to this in the Orange Book (TCSEC) days in the 1980's-1990's was a system fully traceable from requirements to code, proven to embed a security policy, and analyzable and buildable from source locally by the customer using existing, trusted tools. Eventually, people added hashes for the code and data.
So, your program that combines source files or checks dependencies would be fully specified in its success and failure states. Only combinations of functions leading to a provably-secure state are even allowed. If you can't do that, the feature is too complex to allow. Human pentesters review it from design to algorithms to building it to spot ways attacks might happen.
That's what it takes to build software that usually resists subversion. Most software isn't built that way. It can't be because the priorities of developers and customers work against it. So, we'll continue to see clever attacks that exploit systems not designed to high security standards.
For this topic, I recommend David A. Wheeler's page on Software, Configuration Management Security because it covers many issues with it in mostly-centralized systems.
> Most software isn't built that way. It can't be because the priorities of developers and customers work against it.
The most significant such priority may be cost, of paying developers and of time to delivery.
I've been thinking that the dramatic reductions in those costs due to LLMs enables us to produce much more quantity and/or quality. Many complain now about quantity, so perhaps we are finally at a stage where we don't need much more software, and can focus on quality.
In other words, LLMs might enable us to some of these things that were impossible before.
you could backdoor not only the strip command but alot of other commands that work on elf binaries: strings, strace, objdump, nm, ldd, etc
This paper can be boiled down to:
If you have malware on your CI machine it can infect the artifacts it creates.
The Nix project has been able to bootstrap an entire Linux distribution from scratch. However, doing that traditionally relies on binary seeds -- meaning the very first compiler in the chain is downloaded as a prebuilt binary rather than compiled from a fully verified source. This leaves a single foundational gap where users will have to trust trust an external black-box binary. Efforts toward reproducible builds and reducing this trust perimeter focus on removing binary seeds and tracing every compilation step back to a minimal, manually verifiable root.
Ken Thompson's Trusting Trust is an interesting conundrum... there are ways to minimize the need to trust however, if you can express everything in the same language or common runtime:
https://ulanguage.org/ULanguage#trust
In other words: AI can not be trusted.
Nothing about this uses AI in any way. I'm so tired of people injecting it into every conversation.
The attack doesn’t use AI, but an AI could use the attack. (and the researchers definitely used AI to write the paper!)
AI could enable script kiddies to pull this off.
Script kiddies have always been a problem you have to defend against. This is nothing new.
Yes and no. We used to have rampant script kiddies back in the '90s and early 2000s. After 2005-ish, well maybe 2010, most systems became adequate enough to not trust users' input, bug bounties, security as a separate role, etc, etc.
It would take at least some knowledge to hack, not just a random script from a forum.
Now, with LLMs, it's the '90s all over again.
Whilst true, security will improve rapidly again. Potentially via AI, potentially via other technologies.
If its easy enough to find exploits, its likely similarly easy to scan code for exploits, or use AI-based anti-virus technologies. The only thing holding us back is the cost of compute. We can't all run the latest models against everything.
Script kiddies will soon have capabilities that nation states once upon a time could only dream of.