CVE-2023-3773 : Security Advisory and Response

This CVE, titled "Kernel: xfrm: out-of-bounds read of xfrma_mtimer_thresh nlattr," was published by Red Hat on July 25, 2023, with a severity rating of "Moderate."

Understanding CVE-2023-3773

This CVE relates to a flaw found in the Linux kernel's IP framework for transforming packets within the XFRM subsystem. It could allow a malicious user with CAP_NET_ADMIN privileges to trigger an out-of-bounds read, potentially leading to sensitive heap data leakage to userspace.

What is CVE-2023-3773?

The CVE-2023-3773 vulnerability is rooted in the XFRM subsystem of the Linux kernel, presenting a risk of information disclosure due to an out-of-bounds read operation. By exploiting this flaw, an attacker could potentially access sensitive data beyond the allocated memory bounds.

The Impact of CVE-2023-3773

The impact of CVE-2023-3773 could allow an attacker to read beyond the intended boundaries of XFRMA_MTIMER_THRESH, leading to a potential leak of confidential information stored in the heap memory to unauthorized users or applications.

Technical Details of CVE-2023-3773

This vulnerability has a CVSS v3.1 base score of 5.5, categorizing it as having a medium severity level. The attack complexity is considered low, and the attack vector is local. It has a high impact on confidentiality, low impact on integrity, and low impact on availability.

Vulnerability Description

The flaw in the XFRM subsystem of the Linux kernel could result in a 4-byte out-of-bounds read of XFRMA_MTIMER_THRESH during the parsing of netlink attributes, potentially leading to the exposure of sensitive heap data to userspace.

Affected Systems and Versions

The vulnerability affects Red Hat Enterprise Linux versions 7, 8, and 9, as well as Fedora. Specific impacted versions of the kernel package for different environments are listed by Red Hat with corresponding Common Platform Enumeration (CPE) entries.

Exploitation Mechanism

A malicious actor with CAP_NET_ADMIN privileges can exploit this vulnerability by manipulating netlink attributes related to the XFRM subsystem, triggering an out-of-bounds read operation and potentially extracting sensitive data from the kernel's heap memory.

Mitigation and Prevention

To safeguard systems against the CVE-2023-3773 vulnerability, immediate steps should be taken to mitigate the risk and prevent exploitation.

Immediate Steps to Take

Organizations should apply relevant security patches and updates provided by Red Hat for affected systems promptly.
Limit and monitor user privileges, especially those related to CAP_NET_ADMIN, to reduce the potential impact of malicious exploitation.

Long-Term Security Practices

Regularly monitor security advisories and updates from Red Hat and other relevant sources to stay informed about emerging vulnerabilities.
Implement robust access control measures and security best practices to minimize the risk of unauthorized access to sensitive data.

Patching and Updates

Ensure that all affected systems, including Red Hat Enterprise Linux versions 7, 8, and 9, as well as Fedora, are updated with the latest kernel patches released by Red Hat to mitigate the CVE-2023-3773 vulnerability and enhance system security.