CVE-2023-1901 Explained : Impact and Mitigation

This CVE record was published on July 10, 2023, by Zephyr. It pertains to a vulnerability in Zephyr versions less than or equal to 3.3 that could allow a malicious HCI Controller to exploit a dangling reference in the host layer, potentially leading to a Denial of Service (DoS) or Remote Code Execution (RCE).

Understanding CVE-2023-1901

This section will delve into the details of CVE-2023-1901, outlining the vulnerability, its impact, technical aspects, and mitigation strategies.

What is CVE-2023-1901?

The vulnerability identified in CVE-2023-1901 involves the bluetooth HCI host layer logic not clearing a global reference to a semaphore after synchronously sending HCI commands. This flaw could be exploited by a malicious HCI Controller to leverage the dangling reference in the host layer, resulting in a potential crash or unauthorized code execution on the Host layer.

The Impact of CVE-2023-1901

The impact of this vulnerability is considered medium with a base CVSS score of 5.9. It poses a high availability impact, potentially leading to a Denial of Service (DoS) situation where the host layer crashes. Additionally, there is a possibility of Remote Code Execution (RCE) on the Host layer, emphasizing the severity of the issue.

Technical Details of CVE-2023-1901

In this section, we will explore the technical aspects of CVE-2023-1901, including vulnerability description, affected systems, and exploitation mechanisms.

Vulnerability Description

The vulnerability stems from the failure of the bluetooth HCI host layer to clear a global reference to a semaphore post the synchronous transmission of HCI commands. This oversight enables a malicious HCI Controller to exploit the dangling reference, potentially leading to a crash or unauthorized code execution on the Host layer.

Affected Systems and Versions

Zephyr versions less than or equal to 3.3 are impacted by this vulnerability. Specifically, installations with Zephyr version 3.3 and below that utilize the affected bluetooth HCI host layer logic are susceptible to exploitation by a malicious actor.

Exploitation Mechanism

By exploiting the lingering reference to the semaphore within the bluetooth HCI host layer after sending synchronous HCI commands, a malicious HCI Controller can orchestrate a series of actions that may result in a crash of the host layer or unauthorized execution of code, thus compromising system integrity.

Mitigation and Prevention

To address CVE-2023-1901 and enhance system security, appropriate mitigation and prevention measures must be implemented promptly.

Immediate Steps to Take

Users should update their Zephyr installations to version 3.4 or above, where the vulnerability has been fixed.
Organizations are advised to review and restrict access to critical bluetooth HCI functionalities, mitigating the risk of potential exploitation.
Implementing network segmentation and access controls can help limit exposure to malicious actors seeking to exploit the vulnerability.

Long-Term Security Practices

Regular security audits and vulnerability assessments of system components, especially critical protocols like bluetooth HCI, are essential to proactively identify and address potential security gaps.
Training and awareness programs for developers and IT personnel can ensure a culture of security-conscious coding practices and adherence to secure development methodologies.

Patching and Updates

Timely application of security patches and updates released by Zephyr for the affected versions is crucial to remediate the vulnerability and strengthen system resilience against emerging threats.
Establishing a robust patch management process that includes testing and validation of updates before deployment is essential to prevent disruptions and ensure the integrity of the system.

By following these mitigation strategies and best practices, organizations can effectively address CVE-2023-1901 and bolster their overall cybersecurity posture to mitigate risks associated with such vulnerabilities.