The folowing plaintext has been encrypted using an unknown key, with AES-128 CBC:
Original: Pass: sup3r31337. Don’t loose it!
How would you modify it so that it now decrypts to: “Pass: notAs3cre7. Don’t loose it!”
This challenge does not have a specific flag format.
This is going to be an AES-CBC byte flipping attack.
Just take the IV, XOR the first block of the original plaintext with the first of the target plaintext, and patch the IV.
See the differences?
Pass: sup3r31337 . Don't loose it ! Pass: notAs3cre7 . Don't loose it !
And here’s the code: