CVE-2023-20896 Explained : Impact and Mitigation

This CVE-2023-20896 was published on June 22, 2023, by VMware. It affects VMware vCenter Server and VMware Cloud Foundation. The vulnerability involves an out-of-bounds read issue in the DCERPC protocol implementation within the VMware vCenter Server.

Understanding CVE-2023-20896

This section will delve into the specifics of CVE-2023-20896 in terms of its nature, impact, and affected systems.

What is CVE-2023-20896?

The CVE-2023-20896 vulnerability found in VMware vCenter Server allows a malicious individual with network access to trigger an out-of-bounds read through a specially crafted packet. This can lead to a denial-of-service affecting certain services like vmcad, vmdird, and vmafdd.

The Impact of CVE-2023-20896

The CVSS v3.1 score for CVE-2023-20896 is 5.9, categorizing it as a medium-severity vulnerability. With a high attack complexity and network-based attack vector, the availability impact is considered high. While no confidentiality or integrity impact is identified, the exploit doesn't require any special privileges or user interaction.

Technical Details of CVE-2023-20896

In this section, we will explore the vulnerability description, the affected systems and versions, as well as the exploitation mechanism.

Vulnerability Description

The vulnerability resides in the way VMware vCenter Server handles the DCERPC protocol, leading to an out-of-bounds read scenario when processing maliciously crafted packets.

Affected Systems and Versions

VMware vCenter Server versions 8.0 (less than U1b) and 7.0 (less than U3m) are impacted by this vulnerability. Additionally, VMware Cloud Foundation versions 5.x and 4.x are also affected if they are less than 7.0 U3m or 8.0 U1b.

Exploitation Mechanism

By sending a carefully crafted packet to the VMware vCenter Server, a bad actor can exploit this vulnerability to trigger an out-of-bounds read scenario, ultimately leading to service denial.

Mitigation and Prevention

This section will outline the steps to mitigate the CVE-2023-20896 vulnerability and prevent potential exploitation.

Immediate Steps to Take

It is crucial to apply the patches provided by VMware to address this vulnerability promptly. Network segmentation and access control measures can also help limit exposure.

Long-Term Security Practices

Regular security audits, keeping systems up-to-date, and implementing robust network security protocols can fortify the overall resilience of the infrastructure against such vulnerabilities.

Patching and Updates

Ensure that VMware vCenter Server and VMware Cloud Foundation are updated to versions that contain the necessary security fixes to mitigate the risk posed by CVE-2023-20896. Always stay informed about security advisories from VMware to proactively address such vulnerabilities.