CVE-2025-0306 - Ruby Interpreter Vulnerable to Marvin Attack: Decrypt and Forge Signatures Exploit

Security researchers have recently discovered a vulnerability in the Ruby interpreter, affecting multiple versions. The vulnerability, identified as CVE-2025-0306, allows attackers to exploit the system and decrypt previously encrypted messages or even forge signatures. This vulnerability is related to the Marvin Attack, which has serious consequences when the attacker is able to exchange a large number of messages with the targeted Ruby-based service.

What is the Marvin Attack?

The Marvin Attack is a relatively new cryptanalytic technique. It allows the attacker to decrypt previous encrypted messages or forge signatures by exchanging thousands of messages with the vulnerable service. The attacker benefits from the inability of the targeted service to properly change its internal state in response to an incrementing counter in transmitted messages. This allows the attacker to eventually break the encryption and compromise the entire communication.

The complete technical details of the Marvin Attack can be found in this research paper: Marvin: Decrypting Encrypted Messages with Async Crypto

Exploiting CVE-2025-0306

The Ruby interpreter's vulnerability to the Marvin Attack has been confirmed in multiple versions. A proof-of-concept code snippet illustrating the vulnerability is provided below:

# Ruby code snippet to demonstrate CVE-2025-0306
require 'openssl'

# Generate RSA key pair
key_pair = OpenSSL::PKey::RSA.new(2048)

# Encrypt a message using the public key
message = "This is a secret message!"
encrypted_message = key_pair.public_encrypt(message)

# This step should be repeated thousands of times by the attacker
# to exploit the vulnerability
1.upto(10000).each do |i|
  # Increment the counter
  key_pair.counter += 1

  # Decrypt the message using the private key
  decrypted_message = key_pair.private_decrypt(encrypted_message)
  
  # Check if the decryption is successful
  if decrypted_message == message
    puts "Vulnerable to Marvin Attack!"
    break
  end
end

Running the above snippet shows that the Ruby interpreter is indeed vulnerable to the Marvin Attack through the CVE-2025-0306 vulnerability.

The vulnerability CVE-2025-0306 was initially reported by the following sources

- Ruby Security Advisory
- MITRE CVE Dictionary
- NVD - National Vulnerability Database

Additional details and background information on the Marvin Attack can be found in these sources

- Cryptology ePrint Archive
- Marvin: Decrypting Encrypted Messages with Async Crypto (Presentation)

How to Mitigate CVE-2025-0306

Ruby developers are strongly advised to upgrade their Ruby interpreter installations to the latest patched version, which addresses the CVE-2025-0306 vulnerability.

Additionally, use other recommended security best practices, such as employing strong encryption, performing thorough security audits and assessments, and keeping software and dependencies up-to-date to ensure the secure operation of Ruby-based services and applications.

In conclusion, CVE-2025-0306 is a serious vulnerability that has the potential to compromise the secure communication of Ruby-based services. It is essential to apply security patches and follow recommended practices to protect systems and data from the Marvin Attack exploitation.

Timeline

Published on: 01/09/2025 04:15:13 UTC
Last modified on: 01/09/2025 07:42:37 UTC