The Rat Pack New Years CTF 22–23

Ctf writeup

5 min readJan 5, 2023

Pronay Biswas (b0mk35h)

Introduction

The Rat Pack New years CTF 22–23 hosted a CTF on the 4th of January 2023, which was a 12 hour CTF from 4:30a.m. to 4:30p.m. I participated in the CTF using the alias “b0mk35h” and solved 14 challenges and ranked 4th position.

The Challenges I have solved-

The pages below show a summary of how I found the flags by solving the challenges.

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Web Challenge

Roborat

challenge url- https://hackxpert.com/labs/chall2/

As mentioned, the name of this challenge is “roborat”. My first step was to check the “/robots.txt” file of this website and I got the path.

2. By using this path I have got my flag.

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Cryptography challenges

Cryptography — Pt 1

> crypto- ZmxhZ3tJYW1Ob3RDcmF6eSwsLFlPVUFSRSEhfQ==

As I saw last of this crypto there was “==” in the last. “==” define the base 64 encoding. Then I have to use CyberChef to decode it.

2. Cryptography — Pt 2

> It was a very easy challenge. To solve this crypto I used CyberChef and got the flag.

3. Cryptography — Pt 3

> It was a very easy challenge, using CyberChef easily anyone can solve this.

4. xorat

> Based on the name of the challenge, I assume it is a XOR cipher. Then I used the dcode.fr tool to decrypt this file using the XOR cipher.

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Forensics challenges

Remorse

> From the name of this challenge we can understand that it is Morse code. Then I use the Morse code decoder online tool to decode the wav file and get the flag.

2. MOUSE ROLL?

> I first used an online morse code decoder to decode the wav file, since it is a wav file. Then I found that it was not clear. There was something similar called spectrogram.

> Then I had to search for a spectrogram analyzer again to decode the WAV file. And I got the flag.

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JWT

JWT — 1

>JWT stands for “JSON Web Token”. I recall watching a video walkthrough and can apply that experience. I have opened the challenge. Then I right clicked and “inspect element”. Then I click on “Network” and try to find JWT but there is nothing there.

> Then click on the JWT file and watch the response code and find “Bearer…..”

> Copy the value and open a online tool and from there find value false and change the value true.

> Copy the code and past it to the main page and get the flag.

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OSINT

Basic OSINT

> In this challenge, the hints were — “Are you following our posts on social media …”. Then I decide to search Twitter for The XSS Rat gr33nm0nk hAck3rio Twitter profiles one by one. When visiting the hAck3rio Twitter page, I found a tweet with a link.

> I opened the link and got a photo of a “rat”.

> Then I downloaded it and checked the metadata with exiftool and got the flag.

2. OSINT — Part 2

In this challenge a link was given. And also a hint was there which is- “We have a hidden page on https://hackxpert.com/ratsite that is not mentioned in the code. Can you find it together with the flag?”

Then I opened the link and searched for the robots.txt file and got a hidden page.