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Comment by tonnydourado | Hacker News Reader

How many alpine installs are running sshd? Most containers using it as a base image aren't. Embedded Linux is unlikely to be running it, too. And if one IS running sshd, how often is it with unchanged defaults? I don't buy the inference here.

I'll concede that embedded linux might be my blindspot here. Maybe cheap web hosting, too, but that seems much less likely to be using musl.

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Embedded linux is your blindspot here.

Yes

Most embedded systems I've seen use glibc or uClibc. I agree it would make sense for them to use musl, but the embedded space moves very slowly.

Rumor has it that Cisco has been hurriedly patching something and refusing to tell their customers what it is. I'm thinking it's this.

A lot of embedded systems use musl and no PAM. Some of them might use Alpine, but the distribution doesn't matter that much.

And ssh? I'd assume most would use proprietary or industry-specific standard for data IO, or just https, for domestic IoT stuff

And also ssh in many cases.

I thought Dropbear was pretty much the defacto SSH server for embedded applications, is OpenSSH+musl actually a common combination for these scenarios?

Well, OpenWrt is OpenSSH + musl.

OpenWrt uses Dropbear by default:

https://openwrt.org/docs/guide-user/services/ssh/transfer_dr...

We don’t know that dropbear isn’t vulnerable. The bug here is in musl and OpenSSH is just being a bro by working around it

I wouldn't say the bug is only in musl. Musl is probably the "worst" offender here (at least choose something other than "*"!), but the change in sshd was also a little suspect. i.e. the "let's find a user and take their salt (and hashing algorithm) and use it to compute and compare the hash to avoid timing attacks" change.

I haven't thought it through, but I suspect in an ideal world, sshd shouldn't have accepted the user password regardless of the outcome of crypt() if the user did not exist and it only pretended to go through the motions to avoid a timing attack.

Did look into their patch yesterday(?) which seemed to mitigate this issue which they (rightfully IMHO) consider caused by musl. But it seems their fix is to do a sanity check on the supposed hashed password char length, and thus still theoretically still allowing the possibility of those "!!!INVALID_PASSWORD!!!" suggestions to fall through....

Tried it, doesn't work.

Some use Dropbear, some use openssh.

This vulnerability clearly is not one that affects everyone like the PHP vulnerability did. But it's exposure is still significant and very easy to exploit. As easy as it gets.

Most of those would be using dropbear rather than openssh.

> Most containers using it as a base image aren't.

On top of the embedded linux blindspot, this statement seems unfounded.

> if one IS running sshd, how often is it with unchanged defaults?

By definition, I would imagine the answer to this is most of the time.

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