An advanced tool called Padre has been developed to launch and operate Padding Oracle attacks against encryption in CBC. This tool, available on Github, operates by exploiting the way that data is divided into blocks of a certain size in many cryptographic systems, such as those that use block ciphers like AES. The data must be “supplemented” with additional bits to fill the remaining space and the Padding Oracle attack capitalizes on this addition process to gain access to the encrypted data.
In the Padding Oracle attack, the key is unknown, however, the system that knows the key, known as the oracle, can be accessed. Information from the oracle system can be used to decipher the block of encrypted data.
There are several features of Padre that make it a valuable tool for launching Padding Oracle attacks:
- Very fast parallel implementation
- Deciphering of tokens
- Encryption of arbitrary data
- Automatic removal of filling prints
- Automatic determination of the length of the code block
- If a failure occurs during the operation, Padre will tell you how to configure it for a successful attack
- Support for tokens in the parameters of Get/Post, cookies
- Flexible setting of coding rules (Base64, Hex, etc.)
The Padding Oracle attack is dangerous because it can have a significant impact. It allows for the disclosure of encrypted information of the session, bypassing authentication, creation of fake trusted tokens and expanding the attack surface overall.
For more information on Padre and to download the tool, visit the Github page.