Writeups | Status 418

World Wide CTF 2024

All Your Bases Are Belong To Us

Misc

This problem gives us an encoded message along with the hint: [...] The first step is to find that 2ˆ16 is 65536 and, given the hint, the decoding will likely involve `Base65536`. Using an online decoder for `Base65536` does not give us a useful result right away, so more steps are required.

World Wide CTF 2024

Bongcloud

Misc

This problem gives us an endpoint to connect via `netcat`, that is, a persistent TCP connection. It starts by stating that we need to beat the chess bot three times to be considered the chess master and get our reward. What follows is a board of chess with a first move by the server already...

World Wide CTF 2024

Guessy CTF Solver

Web

In this problem we receive the code for an Express.JS API with a single endpoint: /hack. This endpoint received a URL along with paths that will be loaded using the `happy-dom` library and will be searched for flags following the format `PREFIX{...}` (by default `wwf{...}`). The API restricts its...

CyberSci Regional Qualifiers 2024-25

Parts

Crypto

For the most part the encryption mechanism was secure, using a large e, n, p and q values made most attacks unfeasible. The only liability is the block size of four which can be reasonably brute forced, especially when considering the restricted charset of only `[A-Za-z0-9_-]`. I therefore built a...

CyberSci Regional Qualifiers 2024-25

Data is the new Currency

Forensics

This is a pcap forensics challenge, and the intructions give the following hint about what to look for: [...] So let's look at the PCAP: ![Initial view of the PCAP](writeup/image.png) Initally, we can see some HTTP traffic and unencrypted SMTP traffic. Usually, looking at HTTP traffic is a good...