CVE-2023-4389: Detailed Analysis and Mitigation Strategies

Executive Summary

CVE-2023-4389 is a critical vulnerability identified in the Btrfs filesystem of the Linux Kernel. This flaw, due to a double decrement of the reference count in the

btrfs_get_root_ref

function located in

fs/btrfs/disk-io.c

, can be exploited by a local attacker with user privileges to crash the system or potentially leak internal kernel information. The vulnerability has a high severity rating with a CVSS v3.1 Base Score of 7.0. Immediate patching and mitigation are essential to protect systems from potential exploitation.

Technical Information

CVE-2023-4389 is a high-severity vulnerability affecting the Btrfs filesystem in the Linux Kernel. The flaw arises from a double decrement of the reference count in the

btrfs_get_root_ref

function within the

fs/btrfs/disk-io.c

file. This type of vulnerability, known as a double decrement, can lead to significant security issues, including system crashes and information leaks.

The Btrfs filesystem is widely used in various Linux distributions due to its advanced features like snapshotting, pooling, and checksums. However, the identified flaw in the reference count handling can be exploited by a local attacker with user privileges. The attacker can trigger the vulnerability by manipulating the reference count, leading to a system crash or leaking internal kernel information.

The CVSS v3.1 Base Score for this vulnerability is 7.0, indicating a high severity level. The Exploitability Score is 1.0, suggesting that the vulnerability is relatively easy to exploit under certain conditions. The primary impact of this vulnerability includes system crashes and potential information leaks, which could be leveraged for further attacks.

The vulnerability resides in the

btrfs_get_root_ref

function, which is responsible for managing reference counts in the Btrfs filesystem. A double decrement occurs when the reference count is decremented twice, leading to an incorrect count. This can result in the system attempting to free resources that are still in use, causing a crash. Additionally, the incorrect reference count can expose internal kernel information, which could be exploited by attackers to gain further access or escalate privileges.

Exploitation in the Wild

As of the latest updates, there have been no confirmed reports of CVE-2023-4389 being actively exploited in the wild. However, given the nature of the vulnerability and its potential impact, it is crucial to apply patches and updates promptly to mitigate any risks. System administrators should remain vigilant and monitor for any unusual activities that may indicate attempts to exploit this vulnerability.

APT Groups using this vulnerability

Currently, there are no specific APT groups known to be exploiting CVE-2023-4389. However, the high severity and potential impact of this vulnerability make it a likely target for advanced persistent threat actors in the future. Organizations should stay informed about any developments and ensure that their systems are adequately protected.

Affected Product Versions

The vulnerability affects the Btrfs filesystem in the Linux Kernel. Specific versions impacted include:

• Linux Kernel versions prior to the patched release
• Btrfs filesystem implementations in various Linux distributions

Administrators should refer to their respective Linux distribution's security advisories for detailed information on affected versions and available patches.

Workaround and Mitigation

To mitigate the risks associated with CVE-2023-4389, the following steps are recommended:

Apply the latest patches provided by the Linux Kernel maintainers and affected vendors. Regularly update systems to ensure that all security patches are applied promptly.

Monitor systems for unusual activities that may indicate attempts to exploit this vulnerability. Implement robust logging and monitoring solutions to detect and respond to potential threats.

Limit user privileges to reduce the risk of local attackers exploiting this vulnerability. Implement the principle of least privilege to minimize the impact of any potential exploitation.

Consider using additional security measures such as SELinux or AppArmor to provide an extra layer of protection against exploitation attempts.

References

For further details and updates on CVE-2023-4389, please refer to the following sources:

• MITRE CVE-2023-4389 (https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-4389)
• Red Hat Bugzilla #2219271 (https://bugzilla.redhat.com/show_bug.cgi?id=2219271)
• Red Hat Security Advisory (https://access.redhat.com/security/cve/CVE-2023-4389)
• Patchwork Kernel Patch (https://patchwork.kernel.org/project/linux-btrfs/patch/20220324134454.15192-1-baijiaju1990@gmail.com/)
• CVE Details (https://www.cvedetails.com/cve/CVE-2023-4389)
• Recorded Future (https://www.recordedfuture.com/vulnerability-database/CVE-2023-4389)
• Cloud Defense (https://www.clouddefense.ai/cve/2023/CVE-2023-4389)
• SUSE Security (https://www.suse.com/security/cve/CVE-2023-4389.html)
• Ubuntu Security (https://ubuntu.com/security/CVE-2023-4389)
• Feedly CVE (https://feedly.com/cve/CVE-2023-4389)
• OpenCVE (https://www.opencve.io/cve/CVE-2023-4389)
• Vulners (https://vulners.com/cvelist/CVELIST:CVE-2023-4389)

Rescana is here for you

At Rescana, we understand the critical importance of staying ahead of cybersecurity threats. Our Continuous Threat and Exposure Management (CTEM) platform is designed to help you identify, assess, and mitigate vulnerabilities like CVE-2023-4389. We provide comprehensive threat intelligence and proactive security measures to ensure that your systems remain secure.

If you have any questions about this report or need further assistance, please do not hesitate to contact us at ops@rescana.com. We are here to help you navigate the complex landscape of cybersecurity and protect your valuable assets.