External risk intelligence

VMware vCenter Server Remote Code Execution Vulnerability.

CVE advisoryKnown Exploit

CVE-2021-21985

A vulnerability in VMware's vCenter Server allows attackers with network access to execute commands with unrestricted privileges on the host operating system. This poses a significant business risk, potentially leading to system compromise and operational disruption.

3Halo Surface Signal

Server-Side Request Forgery

Vmware Vcenter Server

6.56.77.0

External exposure likelihood

Halo Surface Signal score for CVE-2021-21985

VMware vCenter Server is a management component for virtualization infrastructure. While it is network-accessible and often requires connectivity to host environments, it is typically deployed behind internal management network controls rather than being directly exposed on the public internet, though occasional accidental or intentional exposure occurs.

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability exists within the vSphere Client's Virtual SAN Health Check plug-in. This flaw could permit an attacker to execute commands on the operating system hosting vCenter Server. The potential impact involves unauthorized system access and control.

  • Vulnerable vSphere Client plug-in
  • Flaw in input validation
  • Unrestricted command execution

Attack Path

How an attacker could exploit the issue

The Virtual SAN Health Check plug-in in vCenter Server has a vulnerability that allows for remote code execution. An attacker can exploit this by sending network traffic to port 443. This could result in commands being executed with unrestricted privileges on the vCenter Server's operating system.

  • Network access required.
  • Attacker sends malicious traffic.
  • Unrestricted command execution.

Live Threat

Current exploitation, exposure, and threat context

The identified vulnerability presents a significant risk to organizations. A sophisticated attacker could potentially gain unrestricted command execution on the operating system hosting the affected vCenter Server. This could lead to widespread system compromise, data theft, or disruption of critical business operations. The ease of exploitation and the potential for severe damage necessitate a high level of attention.

  • High attacker skill level required.
  • No access or conditions needed.
  • Significant business risk, treat as urgent.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

The Virtual SAN Health Check plug-in in vCenter Server has a remote code execution vulnerability. This issue can allow a malicious actor with network access to execute commands with unrestricted privileges on the operating system hosting vCenter Server. Given this, organizations should take immediate steps to identify and mitigate risks associated with this vulnerability.

  • Find all vCenter Server instances and identify affected assets.
  • Reduce exposure by isolating risk or limiting network access.
  • Apply vendor fixes, verify remediation, and monitor for related activity.

Frequently asked questions

What is the VMware vCenter Server Remote Code Execution vulnerability?

The vSphere Client's Virtual SAN Health Check plug-in has an improper input validation vulnerability. This allows a remote attacker with network access to port 443 to execute commands with unrestricted privileges on the operating system hosting vCenter Server.

What is the weakness class for CVE-2021-21985?

This vulnerability is associated with CWE-918 (Server-Side Request Forgery), CWE-20 (Improper Input Validation), and CWE-470 (Improper Control of Generation of Code).

How can CVE-2021-21985 be exploited, and what is the scope of impact?

An attacker with network access can exploit this by sending malicious traffic to port 443. The execution of commands has unrestricted privileges on the underlying operating system, affecting the vCenter Server environment.

How relevant is CVE-2021-21985, and is it actively exploited?

This vulnerability is considered highly relevant and presents a significant risk. It has been listed on the CISA Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation and a need for urgent attention.

What steps should be taken to address the VMware vCenter Server RCE vulnerability?

Organizations should identify all vCenter Server instances, determine affected assets, and reduce exposure by isolating risk or limiting network access. Applying vendor-provided patches and verifying remediation are critical. Continuous monitoring for related activity is also advised.

References