CP Plus CP-VNR-3104 Man-in-the-Middle Attack Vulnerability via Private Key Exposure

A vulnerability in the CP Plus CP-VNR-3104 model allows attackers to extract the Elliptic Curve (EC) private key, potentially leading to unauthorized access to sensitive information or the execution of a man-in-the-middle attack. This issue arises from a timing vulnerability in the EC mathematics library of the Bouncy Castle cryptography library, which can expose private key details when an attacker observes timing variations during the generation of deterministic ECDSA signatures.

Impact

Exploitation of this vulnerability could result in the unauthorized disclosure of the EC private key, allowing attackers to intercept and manipulate communications or data exchanges, thereby executing a man-in-the-middle attack.

Reproduction

The vulnerability can be reproduced by uploading a firmware file to the device's update service. The uploaded file is decrypted using a binary that can be executed with QEMU, a user-space emulator. This process involves providing the encrypted firmware file and a decryption key, which is read from a configuration file on the device. Once the firmware is decrypted, it can be analyzed for vulnerabilities, such as the timing issue that exposes the private key during ECDSA signature generation.