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We're given a box to ssh into, lets do this.

$ ssh morpheus@challenges.ringzer0team.com -p 10089
The authenticity of host '[challenges.ringzer0team.com]:10089 ([78.109.87.50]:10089)' can't be established.
ECDSA key fingerprint is SHA256:ay3OoeHJOwmJrQs+ug/kjJHyNCaV3hUcxrqat7jmFI8.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '[challenges.ringzer0team.com]:10089,[78.109.87.50]:10089' (ECDSA) to the list of known hosts.
morpheus@challenges.ringzer0team.com's password:
 888888ba  oo                   d8888888P                    a8888a  d888888P
 88     8b                           .d8'                   d8    8b    88
 88aaaa8P  dP 88d888b. .d8888b.    .d8'   .d8888b. 88d888b. 88  P 88    88    .d8888b. .d8888b. 88d8b.d8b.
 88    8b. 88 88    88 88    88  .d8'     88ooood8 88    88 88 d  88    88    88ooood8 88    88 88  88  88
 88     88 88 88    88 88    88 d8'       88.  ... 88       Y8    8P    88    88.  ... 88    88 88  88  88
 dP     dP dP dP    dP `8888P88 Y8888888P `88888P' dP        Y8888P     dP    `88888P' `88888P8 dP  dP  dP
oooooooooooooooooooooooo     88 ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
                        d8888P
                                    +---------------------------------+
                                    |  Welcome to the Sysadmin track  |
                                    |                                 |
                                    |   - Play nice and play Fair -   |
                                    |                                 |
                                    |----[ info@ringzer0team.com ]----|
Last login: Mon Jul 13 12:46:43 2020 from 69.159.171.94
morpheus@lxc-sysadmin:~$

And let's start poking around:

$ ls -al
morpheus@lxc-sysadmin:~$ ls -al
total 20
dr-x------ 2 morpheus morpheus 4096 Oct 17  2018 .
drwxr-xr-x 8 root     root     4096 May 30  2018 ..
lrwxrwxrwx 1 root     root        9 May 30  2018 .bash_history -> /dev/null
-r-x------ 1 morpheus morpheus  220 Aug 31  2015 .bash_logout
-r-x------ 1 morpheus morpheus 3771 Jun  2  2018 .bashrc
lrwxrwxrwx 1 root     root        9 Oct 17  2018 .mysql_history -> /dev/null
-r-x------ 1 morpheus morpheus  655 May 16  2017 .profile

Huh, I was expecting a readme or something to go off...

$ cat .profile
# ~/.profile: executed by the command interpreter for login shells.
# This file is not read by bash(1), if ~/.bash_profile or ~/.bash_login
# exists.
# see /usr/share/doc/bash/examples/startup-files for examples.
# the files are located in the bash-doc package.
# the default umask is set in /etc/profile; for setting the umask
# for ssh logins, install and configure the libpam-umask package.
#umask 022
# if running bash
if [ -n "$BASH_VERSION" ]; then
    # include .bashrc if it exists
    if [ -f "$HOME/.bashrc" ]; then
	. "$HOME/.bashrc"
    fi
fi
# set PATH so it includes user's private bin directories
PATH="$HOME/bin:$HOME/.local/bin:$PATH"

.local in the path would be useful for phishing, but other than that, nothing interesting.
Let's keep poking around

$ ls -al /home
total 32
drwxr-xr-x  8 root      root      4096 May 30  2018 .
drwxr-xr-x 22 root      root      4096 Jul  7 01:26 ..
dr-x------  2 architect architect 4096 Oct 17  2018 architect
dr-x------  2 cypher    cypher    4096 Oct 17  2018 cypher
dr-x------  2 morpheus  morpheus  4096 Oct 17  2018 morpheus
dr-x------  2 neo       neo       4096 Oct 17  2018 neo
dr-x------  3 oracle    oracle    4096 Oct 17  2018 oracle
dr-xr-x---  2 trinity   neo       4096 Oct 17  2018 trinity
$ ps -aux
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.0  37228  5304 ?        Ss   Jul07   0:44 /sbin/init
root        38  0.0  0.1 158480 106316 ?       Ss   Jul07  10:22 /lib/systemd/systemd-journald
root        84  0.0  0.0  28980  2924 ?        Ss   Jul07   0:02 /usr/sbin/cron -f
syslog      86  0.0  0.0 256392  4208 ?        Ssl  Jul07   2:09 /usr/sbin/rsyslogd -n
root       156  0.0  0.0  65508  6528 ?        Ss   Jul07   2:37 /usr/sbin/sshd -D
root       159  0.0  0.0   4504  1608 ?        S    Jul07   0:10 /bin/sh /root/files/backup.sh -u trinity -p Flag-xxx
root       172  0.0  0.0  15752  2212 pts/2    Ss+  Jul07   0:00 /sbin/agetty --noclear --keep-baud pts/2 115200 38400 9600 vt220
root       175  0.0  0.0  15752  2212 pts/0    Ss+  Jul07   0:00 /sbin/agetty --noclear --keep-baud pts/0 115200 38400 9600 vt220
root       176  0.0  0.0  15752  2212 ?        Ss+  Jul07   0:00 /sbin/agetty --noclear --keep-baud console 115200 38400 9600 vt220
root       177  0.0  0.0  15752  2212 pts/3    Ss+  Jul07   0:00 /sbin/agetty --noclear --keep-baud pts/3 115200 38400 9600 vt220
root       179  0.0  0.0  15752  2212 pts/1    Ss+  Jul07   0:00 /sbin/agetty --noclear --keep-baud pts/1 115200 38400 9600 vt220
mysql      182  0.0  0.2 1282828 190004 ?      Ssl  Jul07   3:53 /usr/sbin/mysqld
root      1353  0.0  0.0  90488  6840 ?        SNs  22:47   0:00 sshd: morpheus [priv]
morpheus  1368  0.0  0.0  90488  3380 ?        SN   22:47   0:00 sshd: morpheus@pts/4
morpheus  1369  0.0  0.0  21180  3740 pts/4    SNs  22:47   0:00 -bash
root      1598  0.0  0.0  65508  6264 ?        Ss   22:50   0:00 sshd: [accepted]
sshd      1599  0.0  0.0  65508   724 ?        S    22:50   0:00 sshd: [net]
root      1600  0.0  0.0   7288   640 ?        S    22:50   0:00 sleep 10
root      1603  0.0  0.0  90340  6816 ?        Ss   22:50   0:00 sshd: unknown [priv]
sshd      1604  0.0  0.0  65508  3336 ?        S    22:50   0:00 sshd: unknown [net]
root      1605  0.0  0.0  90340  6816 ?        Ss   22:50   0:00 sshd: unknown [priv]
sshd      1606  0.0  0.0  65508  3336 ?        S    22:50   0:00 sshd: unknown [net]
morpheus  1607  0.0  0.0  37364  3320 pts/4    RN+  22:50   0:00 ps -aux
root     30389  0.0  0.0  49932  3404 ?        SN   22:00   0:00 su neo -c /bin/monitor
neo      30391  0.0  0.0   4216   612 ?        SNs  22:00   0:00 /bin/monitor

Oh damn, that was easy! Flag-xxx