CVE-2023-25563 : Security Advisory and Response

This CVE-2023-25563 record was published on February 14, 2023, and is related to a vulnerability in GSS-NTLMSSP, a mechglue plugin for the GSSAPI library that implements NTLM authentication. The vulnerability involves multiple out-of-bounds reads when decoding NTLM fields which can lead to a denial of service.

Understanding CVE-2023-25563

This section will provide an overview of what CVE-2023-25563 is, its impact, technical details, and mitigation steps.

What is CVE-2023-25563?

The vulnerability in GSS-NTLMSSP, prior to version 1.2.0, can trigger a denial of service due to multiple out-of-bounds reads when decoding NTLM fields. Specifically, a 32-bit integer overflow condition can result in incorrect checks of buffer length consistency. This issue can be exploited via the

gss_accept_sec_context

entry point if the application allows tokens larger than 4GB in length, potentially leading to a large out-of-bounds read of up to 65KB and a denial-of-service risk.

The Impact of CVE-2023-25563

The impact of CVE-2023-25563 is categorized as medium, with a base score of 5.9. The vulnerability has a high availability impact, with an attack complexity of high and network-based attack vector. Although confidentiality and integrity impacts are none, the potential for a denial of service is significant.

Technical Details of CVE-2023-25563

This section delves into the vulnerability description, affected systems and versions, as well as the exploitation mechanism.

Vulnerability Description

The vulnerability arises from multiple out-of-bounds reads in GSS-NTLMSSP when decoding NTLM fields, leading to a denial-of-service risk. Version 1.2.0 addresses this issue with a patch.

Affected Systems and Versions

The affected system is "gss-ntlmssp" by "gssapi" with versions prior to "< 1.2.0" being at risk of exploitation.

Exploitation Mechanism

Exploiting this vulnerability involves triggering out-of-bounds reads by sending tokens larger than 4GB in length through the

gss_accept_sec_context

entry point, potentially leading to a denial of service.

Mitigation and Prevention

This section focuses on the immediate steps to take, long-term security practices, and the importance of patching and updates.

Immediate Steps to Take

To mitigate the CVE-2023-25563 vulnerability, it is recommended to update the affected systems to version 1.2.0 or higher. Restricting the size of tokens accepted by the application can also help prevent exploitation.

Long-Term Security Practices

Implementing secure coding practices, conducting regular security assessments, and staying informed about software vulnerabilities are crucial for maintaining long-term security posture.

Patching and Updates

Regularly applying security patches and updates from software vendors is essential to address known vulnerabilities like CVE-2023-25563 and enhance overall system security.