The Hacker101 community is moving toward and ephemeral sharing.
Upon launching the instance, you're greeted with a simple interface: a title field and a content box. The site proudly claims it uses 128-bit AES encryption
To understand the attack, we must understand how AES-CBC works.
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Never display explicit cryptographic errors to the end user. Ensure your application returns a generic error message (e.g., "An error occurred while processing your request") for both padding failures and signature failures. hacker101 encrypted pastebin
The Encrypted Pastebin is a web application that allows users to create "pastes"—small snippets of text or code—and securely store them. The key feature, as the name suggests, is that these pastes are encrypted before being stored, making them unreadable to anyone without the proper key.
One common entry point is creating a post and manipulating the encrypted part of the URL, as suggested in some walkthrough discussions. Using PadBuster:
This article provides a comprehensive walkthrough of the challenge, explaining each flag in detail, the cryptographic principles involved, and the broader lessons for bug bounty hunters and penetration testers.
The goal for Flag 3 is to use the SQL injection vulnerability to retrieve data from this tracking table, which contains a history of all pastebin URLs ever generated. The URL for id=1 contains the final flag. The Hacker101 community is moving toward and ephemeral
. In CBC mode, the ciphertext of the previous block is XORed with the plaintext of the current block. By carefully toggling bits in one block of the ciphertext, you can precisely control what the plaintext of the block becomes after decryption. Hacker101 Crypto Attacks video
: You learn how to modify encrypted data so that, when the server decrypts it, the resulting plaintext is changed to whatever you want—like turning a "user" account into an "admin". Encryption Bypass : It demonstrates that even if data is protected by
When you submit a new paste, the application redirects you to a unique URL.
The benefits of using Encrypted Pastebin, particularly in the context of Hacker101, are: This public link is valid for 7 days
By successfully attacking this challenge, you gain a deep understanding of cryptographic implementation flaws and practical experience using tools like PadBuster.
The final flag is the most satisfying, as it combines the cryptographic techniques with a more traditional web vulnerability: (SQLi). Every page loaded by the application triggers a tracking.gif image, which likely logs the request data (like headers, IP, and the accessed URL) in a database table.
At its core, the application claims "military-grade" 128-bit AES encryption. However, it suffers from a classic Padding Oracle
Welcome back to the CTF series! Today, we’re tackling one of the most notorious "Hard" challenges in the Hacker101 CTF Encrypted Pastebin