CVE-2019-1551 Explained : Impact and Mitigation
Learn about CVE-2019-1551, an overflow bug in the x64_64 Montgomery squaring procedure in OpenSSL affecting versions 1.1.1-1.1.1d and 1.0.2-1.0.2t. Find out the impact, affected systems, exploitation mechanism, and mitigation steps.
A bug has been identified in the x64_64 Montgomery squaring procedure used for exponentiation with 512-bit moduli. This CVE affects OpenSSL versions 1.1.1-1.1.1d and 1.0.2-1.0.2t.
Understanding CVE-2019-1551
This CVE involves an overflow bug in the x64_64 Montgomery squaring procedure used for exponentiation with 512-bit moduli.
What is CVE-2019-1551?
The CVE-2019-1551 vulnerability in OpenSSL affects the x64_64 Montgomery squaring procedure used for exponentiation with 512-bit moduli. It does not impact any EC algorithms.
The Impact of CVE-2019-1551
- Attacks against 2-prime RSA1024, 3-prime RSA1536, and DSA1024 are deemed challenging and unlikely to occur due to this defect.
- Attacks against DH512 are considered feasible, but the target would need to reuse the DH512 private key, which is not recommended.
- Applications using the low-level API BN_mod_exp with BN_FLG_CONSTTIME may be affected.
Technical Details of CVE-2019-1551
This section provides detailed technical information about the vulnerability.
Vulnerability Description
The vulnerability involves an overflow bug in the x64_64 Montgomery squaring procedure used for exponentiation with 512-bit moduli.
Affected Systems and Versions
- OpenSSL 1.1.1-1.1.1d
- OpenSSL 1.0.2-1.0.2t
Exploitation Mechanism
The vulnerability can be exploited by attackers to potentially carry out attacks against DH512 if the private key is reused.
Mitigation and Prevention
It is crucial to take immediate steps to address and prevent exploitation of this vulnerability.
Immediate Steps to Take
- Update OpenSSL to version 1.1.1e or 1.0.2u, where the issue has been resolved.
- Avoid reusing the DH512 private key.
- Review and modify applications using the low-level API BN_mod_exp with BN_FLG_CONSTTIME.
Long-Term Security Practices
- Regularly update OpenSSL and other software components to the latest versions.
- Implement secure coding practices to prevent similar vulnerabilities.
Patching and Updates
Ensure timely patching of OpenSSL to the fixed versions (1.1.1e or 1.0.2u) to mitigate the CVE-2019-1551 vulnerability.