• throwa356262 3 hours ago |
    musl only, the quick fix:

         PasswordAuthentication=no
    
    
    Which is a good advice in general.
    • solyin 2 hours ago |
      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 an hour ago |
        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 an hour ago |
        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 an hour ago |
        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 an hour ago |
        > 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 an hour ago |
        1Password subscription and the memorized key. 1Password is the only place my ssh private keys are stored.
      • fn-mote an hour ago |
        The somewhere for password authentication is a place you have physical access. Not ssh.
      • mr_mitm 41 minutes ago |
        I log in via console, either physical or virtual (the latter requires MFA though)
      • worksonmine 21 minutes ago |
        A scenario where all the backups are gone and the server is somehow the only thing that survived is not a very plausible one.
      • MPSimmons 18 minutes ago |
        Does this happen to you a lot? You may have other issues
      • gfv 12 minutes ago |
        PasswordAuthentication=no usually means that ssh stops directly reading /etc/passwd to authenticate, not that it stops accepting passwords completely. You'll still be able to log in with a correct password, provided KbdInteractiveAuthentication is still on, PAM is available, and the PAM policy allows for it.
    • patadura an hour ago |
      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 3 hours ago |
    I presume Dropbear, thus musl-based OpenWrt routers are also not affected? Not that Dropbear has been an example in that regard.
    • manwe150 3 hours ago |
      Since after you posted, various people in the thread have reported dropbear is not affected
    • mijoharas an hour ago |
      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 3 hours ago |
    I'm sure some people running lightweight containers just had a heart attack.
    • smw 2 hours ago |
      I would imagine the vast majority of lightweight containers don't contain an ssh server?
  • jordiburgos 2 hours ago |
    Workaround? Why not a fix?
    • ale42 2 hours ago |
      AFAIU because the bug is in musl and not in OpenSSH
  • entuno 2 hours ago |
    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 2 hours ago |
    Who does PasswordAuthentication=yes in this day and age anyway.
    • ectospheno an hour ago |
      People who use AuthenticationMethods "publickey,password"

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

      • rvz an hour ago |
        Just do no password at all.
        • ectospheno an hour ago |
          Putting the one in 1fa? No thanks.
    • walrus01 an hour ago |
      As this is apparently affecting openwrt, probably a fair number of openwrt users, if I had to guess
    • mhitza 39 minutes ago |
      If you run a cockpit service on your server you will need password authentication enabled, unfortunately.
    • krystalgamer 38 minutes ago |
      it's the default for most systems. I can't remember a time I had to not turn it off.
  • amluto 2 hours ago |
    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 an hour ago |
    >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 an hour ago |
    This looks terrible for musl, what a collection of terrible decisions on their part. I guess I'm staying away from it.
    • sheepscreek 41 minutes ago |
      To err is human. There’s no escaping it, I’m afraid.
      • K0nserv 14 minutes ago |
        I agree entirely, but I'm not sure changing `crypt` to return `"*"` instead of `NULL` on failure qualifies. It's much more of a considered decision, which happens to be very wrong.
  • dust42 20 minutes ago |
    > We are making this release as fast as possible (we learned of the problem yesterday) because we have recently observed multiple cases of rapid bug rediscovery by AI agents, sometimes within hours, and so now consider long embargo periods to be a dangerous practice that primarily benefits attackers.

    I think this will likely become standard. Nevertheless, a few stormy months are ahead.

  • MPSimmons 12 minutes ago |
    Is this actually effective against Alpine? The default install seems to use ! as the placeholder in /etc/shadow instead of * and trying the attack doesn't seem to work.
  • zajio1am 3 minutes ago |
    I would say that PasswordAuthentication=yes is by itself a vulnerability.