CVE-2020-28242 : Vulnerability Insights and Analysis

Asterisk Open Source versions 13.x before 13.37.1, 16.x before 16.14.1, 17.x before 17.8.1, and 18.x before 18.0.1, as well as Certified Asterisk before 16.8-cert5, are affected by a vulnerability that can lead to memory exhaustion and system restart due to a loop caused by changing nonces in outbound INVITE challenges.

Understanding CVE-2020-28242

This CVE involves a critical issue in Asterisk Open Source versions that can result in memory consumption and system instability.

What is CVE-2020-28242?

The vulnerability in Asterisk Open Source versions allows for a continuous loop of INVITE requests when challenged outbound, leading to memory exhaustion and potential system shutdown.

The Impact of CVE-2020-28242

The exploitation of this vulnerability can result in Asterisk consuming increasing amounts of memory, potentially causing system instability, restarts, or shutdowns.

Technical Details of CVE-2020-28242

This section provides more detailed technical information about the vulnerability.

Vulnerability Description

The issue arises when Asterisk faces an outbound INVITE challenge with changing nonces in each response, causing it to send INVITEs in a loop, leading to memory exhaustion.

Affected Systems and Versions

Asterisk Open Source 13.x before 13.37.1
Asterisk Open Source 16.x before 16.14.1
Asterisk Open Source 17.x before 17.8.1
Asterisk Open Source 18.x before 18.0.1
Certified Asterisk before 16.8-cert5

Exploitation Mechanism

The vulnerability is exploited by challenging Asterisk on an outbound INVITE and changing the nonce in each response, triggering a loop of INVITE requests.

Mitigation and Prevention

Protecting systems from this vulnerability requires immediate actions and long-term security practices.

Immediate Steps to Take

Apply the necessary patches provided by Asterisk to address the vulnerability.
Configure outbound authentication on endpoints to prevent the exploitation of this issue.

Long-Term Security Practices

Regularly update and patch Asterisk installations to mitigate known vulnerabilities.
Monitor system memory usage to detect abnormal behavior that may indicate exploitation.

Patching and Updates

Ensure that all affected Asterisk versions are updated to the latest secure releases to prevent the exploitation of this vulnerability.