PWN Bad grades challenge — HTB

SC & ASLR & NX bypass and double pointer tips [x64]

This is a re-uploaded article from years ago. HTB banned it because the challenge was still active. I promised the audience to re-upload it after the challenge is retired.

This is my fourth walkthrough referring to the methodology described here. It will be as always:

• concise,
• straight to the point.
• without the steps that lead to the rabbit hole.

0. Download the binary:

Source: https://app.hackthebox.eu/challenges

1. Basic checks:

2. Spot the first vulnerability — buffer overflow:

• The first vulnerability lies in the total grades counter buffer, which could be overflowed with more than 33 Bytes.
• Make a loop that will add 34 grades to the grade pool.