CVE-2019-1559 : Exploit Details and Defense Strategies
Learn about CVE-2019-1559, a vulnerability in OpenSSL that could lead to data decryption. Find out how to mitigate the risk and protect your systems from exploitation.
CVE-2019-1559, also known as the 0-byte record padding oracle vulnerability in OpenSSL, poses a risk to encrypted data due to a specific behavior in the SSL_shutdown() function.
Understanding CVE-2019-1559
This vulnerability affects OpenSSL versions 1.0.2 through 1.0.2q and was discovered by Juraj Somorovsky, Robert Merget, Nimrod Aviram, Steven Collison, and Andrew Hourselt.
What is CVE-2019-1559?
If an application using OpenSSL encounters a severe protocol error and calls SSL_shutdown() twice, OpenSSL may exhibit different behavior based on the type of error received. This behavior could potentially lead to a padding oracle vulnerability, allowing attackers to decrypt data.
The Impact of CVE-2019-1559
The vulnerability could be exploited to decrypt sensitive information if certain conditions are met, such as the use of specific ciphersuites and the application calling SSL_shutdown() twice.
Technical Details of CVE-2019-1559
This section provides more in-depth technical information about the vulnerability.
Vulnerability Description
When an application using OpenSSL calls SSL_shutdown() twice after encountering a fatal protocol error, the library may respond differently based on the type of error received, potentially leading to a padding oracle vulnerability.
Affected Systems and Versions
- Affected Versions: OpenSSL 1.0.2 through 1.0.2q
- Fixed Version: OpenSSL 1.0.2r
Exploitation Mechanism
- Exploiting the vulnerability requires the use of specific ciphersuites and the application calling SSL_shutdown() twice, even in the presence of a protocol error.
Mitigation and Prevention
Protecting systems from CVE-2019-1559 involves immediate steps and long-term security practices.
Immediate Steps to Take
- Update OpenSSL to version 1.0.2r to mitigate the vulnerability.
- Monitor for any unusual decryption activities that could indicate exploitation.
Long-Term Security Practices
- Regularly update OpenSSL and other software components to address security vulnerabilities promptly.
- Implement network monitoring and encryption best practices to enhance overall security.
Patching and Updates
- Apply patches provided by OpenSSL to address the vulnerability and enhance system security.