Thoughts, writeups, and experiments in cybersecurity and coding
The challenge involves a network service that encrypts data using a combination of RSA and AES-CBC. It reveals vulnerabilities primarily in the AES layer, allowing for a Padding Oracle Attack. An exploit script successfully decrypts the ciphertext and retrieves the flag: ENO{Y4y_a_f4ctor1ng_0rac13}.
Category: Cryptography Difficulty: Medium 1. Challenge Overview The challenge provides a Python script and a remote service. Upon connecting, the server encrypts a hidden flag using a custom scheme and then acts as an oracle, allowing us to encrypt any hex-encoded message of our choice. The core of the encryption lies in a linear transformation … Read more
Category: Crypto / Reverse Difficulty: Easy/Medium 1. Challenge Overview Upon connecting to the server, I was greeted with two integers. Looking at the provided source code, chall.py, I saw that the program takes a secret flag, converts it into a large integer, and then passes it through a function called reduce(a, f) using a random … Read more