MISSION BRIEF
Welcome to the CBC Bit-Flipping Lab. This environment is designed to demonstrate the malleability of the Cipher Block Chaining (CBC) mode of encryption.
In CBC mode, decryption of a block depends on the ciphertext of the previous block. A one-bit change in a ciphertext block will completely scramble its corresponding plaintext block, but will produce a predictable one-bit change in the next plaintext block.
Your Objective: You have intercepted an encrypted session token. The application validates user privileges based on the decrypted content. You must manipulate the ciphertext (specifically the Initialization Vector or a preceding block) to "flip" specific bits in the target block, escalating your privileges from user=guest to user=admin without knowing the encryption key.
Access the vulnerable application instance below to begin the exploitation.