CVE-2021-46837 : Vulnerability Insights and Analysis

A vulnerability in Sangoma Asterisk versions allows an attacker to trigger a crash by manipulating T.38 re-invite responses initiated by Asterisk.

Understanding CVE-2021-46837

What is CVE-2021-46837?

The CVE-2021-46837 vulnerability in Sangoma Asterisk versions enables a crash-triggering attack through T.38 re-invite responses.

The Impact of CVE-2021-46837

The vulnerability allows attackers to crash systems by sending specific image lines with zero ports, exploiting an active topology append operation.

Technical Details of CVE-2021-46837

Vulnerability Description

The crash exploit is a result of an append operation in relation to the active topology, contrary to expected behavior.

Affected Systems and Versions

Sangoma Asterisk 16.x before 16.16.2
Sangoma Asterisk 17.x before 17.9.3
Sangoma Asterisk 18.x before 18.2.2
Certified Asterisk before 16.8-cert7

Exploitation Mechanism

The crash occurs when a specific m=image line with zero port is included in a response to a T.38 re-invite initiated by Asterisk.

Mitigation and Prevention

Immediate Steps to Take

Apply patches provided by Sangoma for the affected versions.
Monitor for any suspicious activity on Asterisk servers.

Long-Term Security Practices

Regularly update and patch Asterisk installations.
Implement network segmentation to limit the impact of potential attacks.
Conduct security audits to identify and address vulnerabilities.
Train personnel on security best practices.

Patching and Updates

Ensure timely installation of security patches released by Sangoma to address the CVE-2021-46837 vulnerability.