Date: Sat, 27 Feb 2021 18:16:11 -0600 From: "J. Hellenthal" <jhellenthal@dataix.net> To: Gareth de Vaux <security@lordcow.org> Cc: FreeBSD-security@freebsd.org Subject: Re: user account disappeared Message-ID: <CBB7DF0D-3729-48F4-B1D1-D1AC5C40FAD2@dataix.net> In-Reply-To: <D5C4A93C-8919-4DAF-B539-A8C0B825BE9B@dataix.net> References: <D5C4A93C-8919-4DAF-B539-A8C0B825BE9B@dataix.net>
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https://www.unix.com/man-page/FreeBSD/8/pwd_mkdb/ --=20 J. Hellenthal The fact that there's a highway to Hell but only a stairway to Heaven says a= lot about anticipated traffic volume. > On Feb 27, 2021, at 18:12, J. Hellenthal <jhellenthal@dataix.net> wrote: >=20 > =EF=BB=BFLooks like your master passwd db is out of sync. >=20 > Command is mkpwdb or something similar then run init q >=20 > Personally it would seem someone got ahold of master.passwd and doesn=E2=80= =99t know how it works or a port upgrade failed to complete properly updatin= g the db >=20 > --=20 > J. Hellenthal >=20 > The fact that there's a highway to Hell but only a stairway to Heaven says= a lot about anticipated traffic volume. >=20 >> On Feb 27, 2021, at 15:23, Gareth de Vaux <security@lordcow.org> wrote: >>=20 >> =EF=BB=BFHi all, one of my users in a jail has mysteriously half disappea= red. I've renamed the user to 'lostuser', the password hash, and the process= it's running to protect privacy below: >>=20 >> I suddenly can't log in over ssh: >>=20 >> sshd[22485]: Invalid user lostuser from XYZ >>=20 >> # su - lostuser >> su: unknown login: lostuser >>=20 >> # ls -ld /home/lostuser >> drwx------ 8 1012 users 18 Jan 23 11:19 /home/lostuser >>=20 >> $HOME still exists but only showing the userid. >>=20 >> # egrep "1012|lostuser" /etc/passwd >> lostuser:*:1012:1000:User &:/home/lostuser:/usr/local/bin/bash >>=20 >> # egrep "1012|lostuser" /etc/master.passwd=20 >> lostuser:$6$9xxxxx/:1012:1000::0:0:User &:/home/lostuser:/usr/local/bin/b= ash >>=20 >> Entries are still in /etc/*passwd ? >>=20 >> # ls -l /etc/*passwd /etc/group >> -rw-r--r-- 1 root wheel 605 Nov 6 16:52 /etc/group >> -rw------- 1 root wheel 4092 Jan 23 12:22 /etc/master.passwd >> -rw-r--r-- 1 root wheel 2621 Jan 23 12:22 /etc/passwd >>=20 >> This process is still running, which is a network server which is still f= unctioning: >>=20 >> # ps aux | grep lostuser >> 1012 56261 0.0 0.1 44952 21288 7 S+J 3Dec20 9:52.21 /us= r/local/bin/python3.6 /home/lostuser/xyz >>=20 >> also obviously showing the userid and not the username. >>=20 >>=20 >> # grep lostuser /var/log/auth.log >> ... >> Dec 31 10:56:34 ns1 sshd[43798]: Accepted publickey for lostuser from xyz= >> Dec 31 10:56:57 ns1 sshd[44133]: Disconnected from user lostuser >> Jan 10 09:37:05 ns1 sshd[9679]: Accepted publickey for lostuser from xyz >> Jan 10 09:37:09 ns1 sshd[10241]: Disconnected from user lostuser >> Jan 23 11:19:11 ns1 sshd[45905]: Accepted publickey for lostuser from xyz= >> Jan 23 11:19:14 ns1 sshd[46228]: Disconnected from user lostuser >> Feb 27 18:06:49 ns1 sshd[93323]: Invalid user lostuser from xyz >> Feb 27 18:06:49 ns1 sshd[93323]: Connection closed by invalid user lostus= er xyz >>=20 >> 23 Jan 2021 was the last successful login, and later that day /etc/*passw= d was touched due to me changing the >> password of a different user, confirmed as the only change from diff'ing a= gainst backups. >>=20 >> Last buildworld upgrade on 3 Nov 2020 (host and jail): >>=20 >> $ uname -a >> FreeBSD ns1.lordcow.org 11.4-STABLE FreeBSD 11.4-STABLE #0 r367290: Tue N= ov 3 12:11:29 SAST 2020 root@lordcow.org:/usr/obj/usr/src/sys/GENERIC a= md64 >>=20 >> The last ports upgrade was 13 Feb 2021, before that I'm not sure. >>=20 >> The last entry in /var/log/userlog was 23 Jul 2020, and: >>=20 >> # ls -l /var/log/userlog=20 >> -rw------- 1 root wheel 4202 Jul 23 2020 /var/log/userlog >>=20 >>=20 >> ie. timeline: >>=20 >> 23 Jul 2020 Last userlog change >> 3 Nov 2020 buildkernel/buildworld and reboot >> 3 Dec 2020 lostuser network server process spawned and still functioning= >> 23 Jan 2021 Last successful login to lostuser >> 23 Jan 2021 Unrelated user's password intentionally changed with passwd >> 13 Feb 2021 ports upgrade >> 27 Feb 2021 Discover user doesn't exist anymore but still has entries in /= etc/*passwd and a process running >>=20 >> Any ideas? >> _______________________________________________ >> freebsd-security@freebsd.org mailing list >> https://lists.freebsd.org/mailman/listinfo/freebsd-security >> To unsubscribe, send any mail to "freebsd-security-unsubscribe@freebsd.or= g"
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