*sshole · sshhole.com
sshhole.com
openssh on musl linux has been letting people into password-less accounts since 2016.

are you affected?

  • is your sshd running on musl? (alpine, openwrt, buildroot, yocto)
  • is it not using pam? alpine’s openssh-server doesn’t by default, or maybe you set UsePAM no
  • are password logins still on? they are by default
  • is there an account with just * as its password? key-only users, ldap users, root on alpine
  • and some other account with a real password?
  • then that * account takes any password between 257 and 1024 characters

on alpine’s official aws and azure images that’s the default alpine user, and it has passwordless doas. so it’s root

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

  • tal@lemmy.todayEnglish
    10·
    3 hours ago

    did you get hacked? check.

    $ grep “Accepted password” /var/log/messages

    That’s a really bad check unless you have an external box receiving logs and you’re looking there, because the first thing that a sophisticated attacker is going to do if they get in as root is remove the signs of their presence.