Traceback
Gaining Access
Nmap scan:
Finding Backdoor
Going to the website revealed that this website has some sort of backdoor left on it.
Reading the page source gave another hint:
For this, we can google 'Some of the best web shells that you might need' and be directed to this repository:
From there, we can create a wordlist of all the possible shells that are available, and use gobuster on the website. We would find that smevk.php is on the website.
We can login with admin:admin and then find a functioning PHP web shell.
Using the Execute part, we can gain a reverse shell on the machine as the webadmin user.
Privilege Escalation
luvit
We can first check our sudo privileges.
There's also a message left behind by the sysadmin user.
luvit is a CLI tool that can be used to execute LUA code. Since we can use sudo on it, we can simply spawn in another shell using os.execute().
Motd-d
When running LinPEAS, we can find that there are some interesting files we can write to:
To exploit this, we would need to trigger the message to be displayed through SSH. As such, we can create a public key and echo it into the authorized_keys file for sysadmin. Afterwards, we need to execute this command:
This would create a bash SUID binary for us to escalate privileges. This 00-header file would need to be placed within the /etc/update-motd.d/ file and then we can SSH in. Afterwards, spawning a root shell is simple.
