CVE-2021-21972 is a critical remote code execution vulnerability found in the vSphere Client (HTML5) of VMware vCenter Server. This vulnerability allows a malicious actor with network access to port 443 to exploit the issue and execute commands with unrestricted privileges on the underlying operating system that hosts vCenter Server. This vulnerability affects several versions of VMware vCenter Server, specifically versions 7.x prior to 7.0 U1c, 6.7 prior to 6.7 U3l, and 6.5 prior to 6.5 U3n, as well as VMware Cloud Foundation versions 4.x prior to 4.2 and 3.x prior to 3.10.1.2.
With a CVSS score of 9.8, this vulnerability is classified as critical. The high severity rating indicates significant potential for impact to organizations, particularly regarding confidentiality, integrity, and availability. As attackers may leverage this vulnerability to gain unauthorized access, the urgency for organizations to address this issue cannot be overstated.
Organizations should prioritize patching immediately to mitigate the risk associated with this vulnerability. The availability of a known exploit further emphasizes the need for rapid remediation efforts to protect systems and data.
The vulnerability was publicly disclosed on February 24, 2021, and has been included in the Known Exploited Vulnerabilities (KEV) catalog as of November 3, 2021. This inclusion highlights its exploitation in the wild, underscoring the importance of timely updates.
Given the critical nature of this vulnerability, it is essential for organizations to remain vigilant and proactive in their security measures. Regular vulnerability assessments and prompt application of security patches are vital in maintaining a secure environment.
Vulnerability Details
The official description of CVE-2021-21972 states that the vSphere Client (HTML5) contains a remote code execution vulnerability in a vCenter Server plugin. The vulnerability allows attackers with network access to port 443 to execute commands with unrestricted privileges on the underlying operating system that hosts vCenter Server.
This vulnerability is classified under CWE-22, which indicates improper handling of special elements in a file path. The vulnerability impacts the following products: VMware vCenter Server (versions 7.x before 7.0 U1c, 6.7 before 6.7 U3l, and 6.5 before 6.5 U3n) as well as VMware Cloud Foundation (versions 4.x before 4.2 and 3.x before 3.10.1.2).
This vulnerability has a CVSS v3.1 score of 9.8, indicating critical severity. It is characterized by a network attack vector, low attack complexity, no required privileges, no user interaction needed, and high impacts on confidentiality, integrity, and availability.
Technical Analysis
The root cause of CVE-2021-21972 lies in the vCenter Server plugin's inability to securely handle input, allowing attackers to exploit this weakness for remote code execution. The attack vector is network-based, meaning that any attacker with access to the network can initiate an exploit without needing physical access to the affected system.
The attack complexity is classified as low, which indicates that the exploit does not require specialized conditions and can be executed easily. Additionally, no privileges are required for exploitation, and no user interaction is needed to trigger the vulnerability. The impacts of this vulnerability are severe: it can lead to complete compromise of the confidentiality, integrity, and availability of the affected systems.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2021-21972 is significant due to its critical nature and ease of exploitation. Organizations utilizing affected versions of VMware vCenter Server and VMware Cloud Foundation must be aware of the potential for unauthorized access and control over their systems. The blast radius of this vulnerability is extensive as it can affect all instances of the vulnerable software across an organization’s infrastructure.
The urgency assessment based on CVSS indicates that organizations must address this vulnerability immediately. With the known exploitation in the wild, the potential for data breaches and operational disruption is high. Organizations are advised to review their deployment of VMware products and prioritize the application of patches.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | Yes |
Ransomware Use | Yes |
Affected Versions
Affected versions include VMware vCenter Server (7.x before 7.0 U1c, 6.7 before 6.7 U3l, and 6.5 before 6.5 U3n) and VMware Cloud Foundation (4.x before 4.2 and 3.x before 3.10.1.2). Organizations should check their systems to ensure they are not running any of these vulnerable versions.
Mitigation & Remediation
To mitigate the risks associated with CVE-2021-21972, organizations should apply updates per vendor instructions. The specific patches for vulnerable versions are critical for remediation. If a patch is not immediately available, organizations should implement network segmentation to limit exposure and closely monitor network traffic for suspicious activity.
Organizations should also consider engaging in penetration testing to validate defenses and ensure the effectiveness of security measures.
Detection Guidance
Organizations should monitor logs for unusual activity, particularly relating to the vCenter Server. Key indicators may include unexpected command executions or access attempts from unauthorized IP addresses. Behavioral anomalies in user activity or system stability should also be investigated.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-21972 highlights the critical need for organizations to maintain a robust vulnerability management program. This incident represents a pattern of increasing sophistication in attacks targeting critical infrastructure, emphasizing the necessity for proactive security measures.
Security teams should evaluate their current defenses against similar vulnerabilities and consider adopting a more aggressive approach to patch management and security testing. Engaging in penetration testing methodology can provide insights into potential weaknesses and help fortify defenses.
Ultimately, the strategic defensive takeaway from this vulnerability is the importance of integrating security into the development lifecycle and fostering a culture of security awareness within organizations.
Continuous monitoring and security assessments should become integral parts of an organization’s operational framework to adapt to evolving threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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