Certified Ethical Hacker (CEH) Practice Question

CBC mode is malleable because each plaintext block is produced by XOR-ing the decrypted ciphertext block with the previous ciphertext block (or IV for the first block). By flipping chosen bits in the IV or a preceding ciphertext block, an attacker can deterministically flip corresponding bits in the following plaintext block. This technique is known as a CBC bit-flipping attack and works even when the key remains unknown. A padding-oracle attack targets padding validation to recover plaintext, not to predictably modify it. Meet-in-the-middle attacks require two independent encryption stages (e.g., 2DES) and are ineffective against single-key AES. Simply replaying or substituting whole ciphertext blocks does not provide fine-grained control over individual plaintext bits.