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How the CVE Works:
The vulnerability in Ed25519-Java (up to version 0.3.0) arises due to a missing scalar range check during the EdDSA (Edwards-curve Digital Signature Algorithm) signature verification process. EdDSA is designed to provide strong security guarantees, including SUF-CMA (Strong Existential Unforgeability under Chosen Message Attacks). However, the implementation in Ed25519-Java fails to validate whether the scalar used in the signature falls within the acceptable range. This omission allows an attacker to craft a new valid signature for a known message by manipulating the scalar value. As a result, the signature becomes malleable, meaning multiple distinct signatures can be generated for the same message, undermining the integrity and non-repudiation properties of the cryptographic system.
DailyCVE Form:
Platform: Ed25519-Java
Version: 0.3.0 and earlier
Vulnerability: Signature Malleability
Severity: Moderate
Date: Mar 13, 2025
What Undercode Say:
Exploitation:
1. Exploit Code Example:
from ed25519 import SigningKey, VerifyingKey Attacker manipulates the scalar to create a new signature def exploit_malleability(message, original_signature): manipulated_scalar = manipulate_scalar(original_signature) new_signature = create_signature_with_scalar(message, manipulated_scalar) return new_signature
2. Steps to Exploit:
- Obtain a valid signature for a known message.
- Manipulate the scalar value within the signature.
- Generate a new valid signature using the manipulated scalar.
- Use the new signature to bypass signature verification checks.
Protection:
1. Patch Implementation:
- Update to the latest version of Ed25519-Java (post-0.3.0) where the scalar range check is enforced.
- Ensure the scalar value is within the valid range during signature verification.
2. Code Fix Example:
public boolean verifySignature(byte[] message, byte[] signature) {
if (!isScalarInRange(signature)) {
throw new SecurityException("Invalid scalar range detected.");
}
// Proceed with normal verification
return ed25519.verify(message, signature);
}
3. Additional Mitigations:
- Use cryptographic libraries that have been formally verified for SUF-CMA compliance.
- Regularly audit cryptographic implementations for compliance with standards.
4. Commands for Verification:
- Use static analysis tools to detect missing range checks in cryptographic code.
- Example: `bandit -r ed25519-java/` to scan for security issues.
5. Monitoring:
- Monitor logs for repeated signature verification failures, which may indicate exploitation attempts.
- Example: `grep “Signature verification failed” /var/log/auth.log`
6. References:
- bash
- bash
By addressing this vulnerability, developers can ensure the integrity and non-repudiation of their cryptographic systems.
References:
Reported By: https://github.com/advisories/GHSA-p53j-g8pw-4w5f
Extra Source Hub:
Undercode
