CVE-2017-3737 : Vulnerability Insights and Analysis

OpenSSL 1.0.2b-1.0.2m introduced an error state mechanism that could lead to a security bypass vulnerability.

Understanding CVE-2017-3737

Starting from version 1.0.2b, a mechanism called "error state" was introduced in OpenSSL 1.0.2 to handle fatal errors during handshakes.

What is CVE-2017-3737?

The error state mechanism in OpenSSL 1.0.2 does not function properly when SSL_read() or SSL_write() is directly called, potentially allowing a security bypass.

The Impact of CVE-2017-3737

Exploiting this issue requires an application bug triggering a call to SSL_read()/SSL_write() after a fatal error, affecting versions 1.0.2b to 1.0.2m.

Technical Details of CVE-2017-3737

OpenSSL 1.0.2 introduced an error state mechanism that could be exploited under specific conditions.

Vulnerability Description

The error state mechanism in OpenSSL 1.0.2 does not work correctly when SSL_read() or SSL_write() is directly called, potentially allowing data to be passed without encryption/decryption.

Affected Systems and Versions

Versions 1.0.2b to 1.0.2m of OpenSSL are affected by this vulnerability.

Exploitation Mechanism

To exploit this issue, an application bug must trigger a call to SSL_read()/SSL_write() after receiving a fatal error during a handshake.

Mitigation and Prevention

Steps to address and prevent the CVE-2017-3737 vulnerability.

Immediate Steps to Take

Update OpenSSL to version 1.0.2n, where the issue has been resolved.
Monitor for any unusual SSL_read()/SSL_write() calls after handshake failures.

Long-Term Security Practices

Regularly update OpenSSL to the latest versions to patch known vulnerabilities.
Implement secure coding practices to minimize the risk of triggering such vulnerabilities.

Patching and Updates

Ensure timely application of security patches and updates to OpenSSL to mitigate potential risks.