Breaking Down the Bit Flipping Attack in AES CBC

How to exploit this type of attack on symmetric ciphers that rely on CBC as a mode of operation

Francesco Pastore
8 min readApr 1, 2024

Bit-flipping attacks are a common threat to cryptographic algorithms, especially for symmetric ciphers operating in CBC mode.

In these scenarios, knowledge of the plaintext format and the ability to modify the ciphertext allows the attacker to manipulate the encrypted data at will.

In this article, we will explore the CBC operation of AES and see how bit-flipping attacks can be exploited in this particular algorithm.

Photo by Andriyko Podilnyk on Unsplash

AES and symmetric ciphers

The Advanced Encryption Standard (AES) is one of the most widely used encryption algorithms. Developed in 1998, it is still a de facto standard by the U.S. government and many other organizations around the world.

TLS, the cryptographic protocol used by HTTPS for example, can work with this algorithm, showing how important and popular it still is.

AES is a symmetric cipher, which means that a single key is used for both encryption and decryption.

It is also a block cipher, which means that the data is divided into blocks of fixed size, and then each block (128 bits) is…



Francesco Pastore

An engineering student in Milan and a web developer for an IT company. Write about programming and cybersecurity topics.