CVE-2023-27601 Explained : Impact and Mitigation

This CVE involves a vulnerability in OpenSIPS related to the codec_delete_XX() functions. It was published on March 15, 2023.

Understanding CVE-2023-27601

This vulnerability affects versions of OpenSIPS prior to 3.1.7 and 3.2.4. It causes the server to crash when a malformed SDP body is received and processed by the

delete_sdp_line

function in the sipmsgops module.

What is CVE-2023-27601?

OpenSIPS, a Session Initiation Protocol (SIP) server implementation, experiences a crash due to improper handling of an SDP body that does not terminate with a line feed character. This vulnerability was discovered during fuzz testing against an OpenSIPS server utilizing specific functions, leading to a denial of service risk.

The Impact of CVE-2023-27601

Exploiting this vulnerability enables an attacker to crash the server, particularly affecting configurations using functions like

codec_delete_except_re

. This can trigger an

abort

in the lumps processing function, resulting in a Denial of Service.

Technical Details of CVE-2023-27601

This section delves into the specifics of the vulnerability.

Vulnerability Description

The vulnerability arises from the

delete_sdp_line

function's expectation of an SDP line ending with a line feed character. By sending a malformed SDP body, an attacker can trigger a server crash.

Affected Systems and Versions

Versions of OpenSIPS prior to 3.1.7 and 3.2.4 are impacted by this vulnerability, particularly configurations using functions reliant on the vulnerable code.

Exploitation Mechanism

The vulnerability can be exploited by sending a malformed SDP body that does not end with a line feed character, leading to a server crash and denial of service.

Mitigation and Prevention

To address CVE-2023-27601, follow these important steps:

Immediate Steps to Take

Upgrade OpenSIPS to version 3.1.7 or 3.2.4 to mitigate the vulnerability.
Implement strict input validation mechanisms to prevent malformed SDP bodies from causing crashes.

Long-Term Security Practices

Regularly update and patch OpenSIPS to protect against known vulnerabilities.
Conduct thorough security testing, including fuzzing, to identify and address potential weaknesses.

Patching and Updates

Ensure that OpenSIPS is kept updated with the latest security patches and fixes to mitigate the risk posed by vulnerabilities like CVE-2023-27601.