Encrypted Pastebin [2021] — Hacker101

This is where the real challenge begins. The error message from Flag 0 reveals that the backend is written in Python. Further manipulation of the post parameter can trigger a specific error: PaddingException .

The application allows users to submit a title and body via a POST form, after which the server generates an encrypted URL that reflects the submitted content. The encryption is performed using AES-128-CBC, with the ciphertext passed as a post parameter in the URL.

While the claim of "military-grade encryption" sounds impressive, the implementation contains critical flaws that allow attackers to retrieve sensitive data. hacker101 encrypted pastebin

: Prefer authenticated encryption like AES-GCM , which prevents these types of tampering attacks entirely. AI responses may include mistakes. Learn more

[Altered Ciphertext Block 1] ---> Decryption Cipher ---> XORed with [Original Vector] = [Target Plaintext Block 2] Use code with caution. This is where the real challenge begins

Look closely at the error response. If you see "Padding Exception" or a distinct error behavior compared to changing bytes early in the string, a padding oracle exists. 3. Automating the Script

A dedicated automated command-line tool for padding oracle exploits. The application allows users to submit a title

This means:

: Many writeups, such as this one on Medium , demonstrate how to write a Python script to automate the requests and XOR operations.

Let me know which part of the challenge you'd like to explore further. Share public link

To retrieve Flag 1, participants must: