user account disappeared

[J. Hellenthal]

https://www.unix.com/man-page/FreeBSD/8/pwd_mkdb/

-- 
 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 at dataix.net> wrote:
> 
> Looks like your master passwd db is out of sync.
> 
> Command is mkpwdb or something similar then run init q
> 
> Personally it would seem someone got ahold of master.passwd and doesn’t know how it works or a port upgrade failed to complete properly updating the db
> 
> -- 
> 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 15:23, Gareth de Vaux <security at lordcow.org> wrote:
>> 
>> Hi all, one of my users in a jail has mysteriously half disappeared. I've renamed the user to 'lostuser', the password hash, and the process it's running to protect privacy below:
>> 
>> I suddenly can't log in over ssh:
>> 
>> sshd[22485]: Invalid user lostuser from XYZ
>> 
>> # su - lostuser
>> su: unknown login: lostuser
>> 
>> # ls -ld /home/lostuser
>> drwx------  8 1012  users  18 Jan 23 11:19 /home/lostuser
>> 
>> $HOME still exists but only showing the userid.
>> 
>> # egrep "1012|lostuser" /etc/passwd
>> lostuser:*:1012:1000:User &:/home/lostuser:/usr/local/bin/bash
>> 
>> # egrep "1012|lostuser" /etc/master.passwd 
>> lostuser:$6$9xxxxx/:1012:1000::0:0:User &:/home/lostuser:/usr/local/bin/bash
>> 
>> Entries are still in /etc/*passwd ?
>> 
>> # 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
>> 
>> This process is still running, which is a network server which is still functioning:
>> 
>> # ps aux | grep lostuser
>> 1012      56261  0.0  0.1   44952   21288  7  S+J   3Dec20    9:52.21 /usr/local/bin/python3.6 /home/lostuser/xyz
>> 
>> also obviously showing the userid and not the username.
>> 
>> 
>> # 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 lostuser xyz
>> 
>> 23 Jan 2021 was the last successful login, and later that day /etc/*passwd was touched due to me changing the
>> password of a different user, confirmed as the only change from diff'ing against backups.
>> 
>> Last buildworld upgrade on 3 Nov 2020 (host and jail):
>> 
>> $ uname -a
>> FreeBSD ns1.lordcow.org 11.4-STABLE FreeBSD 11.4-STABLE #0 r367290: Tue Nov  3 12:11:29 SAST 2020     root at lordcow.org:/usr/obj/usr/src/sys/GENERIC  amd64
>> 
>> The last ports upgrade was 13 Feb 2021, before that I'm not sure.
>> 
>> The last entry in /var/log/userlog was 23 Jul 2020, and:
>> 
>> # ls -l /var/log/userlog 
>> -rw-------  1 root  wheel  4202 Jul 23  2020 /var/log/userlog
>> 
>> 
>> ie. timeline:
>> 
>> 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
>> 
>> Any ideas?
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