Yet another Hacker News

OpenSSH 10.6p2 has been released with a workaround for a critical vulnerability

77 points Animux 3 hours ago 30 comments

throwa356262 2 hours ago | parent

musl only, the quick fix:

     PasswordAuthentication=no

Which is a good advice in general.

solyin 1 hour ago | parent

How do you break back into your digital life? You wake up in a strange place. Something happened. Everything's gone. No wallet/keys/smartphone/tablet/laptop. How would you get back into your digital life given only a laptop with access to the Internet, unless something, somewhere is passwordauthenticate=yes.

INTPenis 51 minutes ago | parent

Yeah your vault has password authentication. Your password manager in other words. Your vault is where you store your private ssh keys, and or the passwords for the keys.

viraptor 35 minutes ago | parent

Remotely: An encrypted file with a seed / master passwords to all the other data, published under a public url you can remember, but not linked anywhere and not listed.

Locally: Same, but printed out, laminated, in a safe place with other documents.

denkmoon 35 minutes ago | parent

I walk to my pc and type ssh-keygen. If i can’t do that I’ve got bigger problems. “I must be able to recover remotely using a memorised credential” is a terrible requirement.

jareklupinski 33 minutes ago | parent

> You wake up in a strange place. Something happened. Everything's gone. No wallet/keys/smartphone/tablet/laptop.

at this point the _last_ thing i care about is my email.

where am i? am i ok? how are my friends/loved ones?

once those are in place, it becomes clearer how to get back to "normal"

petesergeant 22 minutes ago | parent

1Password subscription and the memorized key. 1Password is the only place my ssh private keys are stored.

fn-mote 22 minutes ago | parent

The somewhere for password authentication is a place you have physical access. Not ssh.

mr_mitm 8 minutes ago | parent

I log in via console, either physical or virtual (the latter requires MFA though)

patadura 25 minutes ago | parent

imo this is a good advice only if the devices that connect to the server have their home encrypted and ssh private key protected.

phoronixrly 2 hours ago | parent

I presume Dropbear, thus musl-based OpenWrt routers are also not affected? Not that Dropbear has been an example in that regard.

manwe150 2 hours ago | parent

Since after you posted, various people in the thread have reported dropbear is not affected

mijoharas 16 minutes ago | parent

There is this write-up/fancy page from the person who found the vulnerability[0] (HN discussion[1], how I found this thread).

At the bottom of that it says dropbear is unaffected.

> on debian, ubuntu, fedora or anything else with glibc? going through pam? dropbear? openbsd? you're fine

[0] https://sshhole.com/

[1] https://news.ycombinator.com/item?id=50378228

crest 2 hours ago | parent

I'm sure some people running lightweight containers just had a heart attack.

smw 1 hour ago | parent

I would imagine the vast majority of lightweight containers don't contain an ssh server?

jordiburgos 1 hour ago | parent

Workaround? Why not a fix?

ale42 1 hour ago | parent

AFAIU because the bug is in musl and not in OpenSSH

entuno 1 hour ago | parent

Seems slightly confusing that the OpenSSH release notes page says:

> This release contains a critical security workaround that affects Linux systems that use the musl libc and PAM disabled.

But that there's nothing about it on their security page.

Even if it's not technically a bug in their code, the fact that they've made a "critical" release to address it suggests that it should probably be listed on the security page as well. But maybe (hopefully) they just haven't updated the security page yet.

asdfsa32 1 hour ago | parent

Who does PasswordAuthentication=yes in this day and age anyway.

ectospheno 40 minutes ago | parent

People who use AuthenticationMethods "publickey,password"

You must present a key first after which you must enter a password.

rvz 25 minutes ago | parent

Just do no password at all.

ectospheno 18 minutes ago | parent

Putting the one in 1fa? No thanks.

walrus01 17 minutes ago | parent

As this is apparently affecting openwrt, probably a fair number of openwrt users, if I had to guess

mhitza 5 minutes ago | parent

If you run a cockpit service on your server you will need password authentication enabled, unfortunately.

amluto 1 hour ago | parent

Wow, what a bug. I expect the exploit is literally as simple as trying to ssh in as a user with the password has ‘*’ in /etc/shadow and typing anything as the password.

To the extent that systems that are configured in the vulnerable manner exist in the wild, I’m surprised they weren’t exploited years ago by trivial ssh bots.

P.S. Wow, I’m reminded of just how awful traditional UNIX-y C APIs and code are.

P.P.S. The musl code in question is nuts. The API it implements is awful. Seriously, here’s the manpage:

https://man.archlinux.org/man/crypt.3.en

You can’t call this function correctly. sshd’s “fix” is basically to assume that a too-short return is an error return instead of a success return.

PAM is also awful, but this is worse.

jmclnx 24 minutes ago | parent

>We consider the root cause of this bug to be outside OpenSSH itself, but we're in a good position to deliver a mitigation quickly.

So not a ssh issue but an issue specific to Linux using "musl libc without PAM".

K0nserv 19 minutes ago | parent

This looks terrible for musl, what a collection of terrible decisions on their part. I guess I'm staying away from it.

sheepscreek 7 minutes ago | parent

To err is human. There’s no escaping it, I’m afraid.