Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Acme.sh runs arbitrary commands from a remote server

github.com

Post reply on HN
Print view View original

21–30 of 71 posts

Re: Acme.sh runs arbitrary commands from a remote server

#21

Post by paulgb »

Vecr wrote: post #16

Even if this is just RCE in the script somehow (I doubt it, it can probably do anything the user running it can), it's horrifying. It means the certificate authority could just take your newly generated certificates and upload them anywhere they want. That's a catastrophic compromise in the TLS security model.

If the CA is compromised, can’t they just bypass ACME verification and generate a cert for your domain anyway?

Re: Acme.sh runs arbitrary commands from a remote server

#22

Post by mholt »

0x0 wrote: post #15
agwa wrote: post #14

Earlier quoted context omitted.

> So the person claiming to be the founder of "QuantumCA" does not possess the private key corresponding to https://crt.sh/?caid=200960 - can we be sure the private key is only accessible by ssl.com's CA system? So the certificates listed here aren't issued by this person, but by the ssl.com's system? https://crt.sh/?Identity=%25&iCAID=200960&exclude=expired&de ... Correct. You can see the Quantum intermediates liste…

I find it troubling that a root CA (ssl.com) is apparently OK with lending their name in a business relationship with an actor that is actively exploiting an acme.sh 0day.

I honestly don't think anyone else knew about the RCE until yesterday.

Re: Acme.sh runs arbitrary commands from a remote server

#23

Post by mholt »

paulgb wrote: post #21
Vecr wrote: post #16

Even if this is just RCE in the script somehow (I doubt it, it can probably do anything the user running it can), it's horrifying. It means the certificate authority could just take your newly generated certificates and upload them anywhere they want. That's a catastrophic compromise in the TLS security model.

If the CA is compromised, can’t they just bypass ACME verification and generate a cert for your domain anyway?

Yes, but with serious consequences (it would go into public transparency logs, at least for CAs in most public root stores).

If the CA can access your private key, then it can reuse (or worse, redistribute) it without anyone knowing.

Re: Acme.sh runs arbitrary commands from a remote server

#24

Post by Vecr »

paulgb wrote: post #21
Vecr wrote: post #16

Even if this is just RCE in the script somehow (I doubt it, it can probably do anything the user running it can), it's horrifying. It means the certificate authority could just take your newly generated certificates and upload them anywhere they want. That's a catastrophic compromise in the TLS security model.

If the CA is compromised, can’t they just bypass ACME verification and generate a cert for your domain anyway?

Yeah, but that's more likely to be noticed in cert transparency and by the website operator, as there's either a duplicate cert in the log or the website server does not work.

Re: Acme.sh runs arbitrary commands from a remote server

#25

Post by dspillett »

paulgb wrote: post #21
Vecr wrote: post #16

Even if this is just RCE in the script somehow (I doubt it, it can probably do anything the user running it can), it's horrifying. It means the certificate authority could just take your newly generated certificates and upload them anywhere they want. That's a catastrophic compromise in the TLS security model.

If the CA is compromised, can’t they just bypass ACME verification and generate a cert for your domain anyway?

The CA isn't directly compromised so a third party couldn't generate any arbitrary certificate this way. Essentially though, assuming my understanding is correct, it would allow them to be a man-in-the-middle and take copies of the keys & certificates used by this tool, allowing them to use keys and certificates generated by that tool. Also, if such a tool is run by root (bad practise, but not uncommon practise) or other significantly privileged user, they potentially have access to far more.

Re: Acme.sh runs arbitrary commands from a remote server

#26

Post by chunk_waffle »

regecks wrote: post #5

I think the title buries the most horrifying part of this. The HiCA certificate authority is relying on an RCE to do an end-run around the semantics of the ACME HTTP-01 validation method. Fucked up and they should be booted from every root program for this.

When confronted they just flat out shut down the service. They also donated $1000 to the project, and they've redirected requests to their payment site to the US White House's website, and they're from China.

They were also suggesting that user's ran the utility as root...

All really shady...

Re: Acme.sh runs arbitrary commands from a remote server

#27

Post by predictabl3 »

Sounds about par for the course for folks that think shell is a productively sustainable way of writing secure or reliable software. Not even remotely sorry about that opinion. The gall to claim ACME compat, then force require a single client, all so you can remote execute arbitrary commands. Should be enough to ruin the CA, but we know how people handle things like this "oh, won't affect me" (until it does). Seemingly just so they can avoid some reverse proxy rules to host the challenge endpoints at the right place? Holy wow. Oh there we go baby, eval'ing with arbitrary input in the shell script, complete with lazy inproper string quoting. I should probably just stop before I say more unkind things.

Was it even run through shellcheck?!

Stop writing this stuff in shell people. 95% of the time I review any (posix, nushell lacks most of these issues) shell scripts, it's obvious they would fall apart the second any string unexpectedly had a space in it. Even scripts written by darling companies of HN.

Post reply on HN