CVE-2021-22005 in vCenter Server
Summary
by MITRE • 09/24/2021
The vCenter Server contains an arbitrary file upload vulnerability in the Analytics service. A malicious actor with network access to port 443 on vCenter Server may exploit this issue to execute code on vCenter Server by uploading a specially crafted file.
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Analysis
by VulDB Data Team • 01/30/2025
The vulnerability identified as CVE-2021-22005 represents a critical arbitrary file upload flaw within VMware vCenter Server's Analytics service component. This vulnerability exists in the server's web application interface where proper input validation and file type restrictions are insufficiently implemented, allowing attackers to bypass security controls and upload malicious files to the target system. The Analytics service, which is designed to collect and process performance data from virtualized environments, inadvertently provides an attack vector that enables remote code execution through crafted file uploads. The flaw specifically affects VMware vCenter Server versions prior to 7.0 U1c and 6.7 U3k, making it a widespread concern across enterprise virtualization environments.
The technical exploitation of this vulnerability occurs through a combination of insufficient server-side validation and inadequate file extension filtering mechanisms. Attackers can upload specially crafted files with extensions that appear legitimate but contain malicious payloads, such as web shells or executable code. The vulnerability stems from improper sanitization of file names and content, allowing attackers to upload files that can be executed within the context of the vCenter Server process. This arbitrary file upload capability enables malicious actors to gain persistent access to the vCenter Server infrastructure, potentially leading to complete compromise of the virtualized environment. The attack requires only network connectivity to the standard HTTPS port 443, making it particularly dangerous as it can be exploited from external networks without requiring additional authentication credentials.
The operational impact of CVE-2021-22005 extends far beyond simple code execution, as vCenter Server serves as the central management point for VMware virtual environments. Successful exploitation allows attackers to gain administrative control over the entire vCenter infrastructure, potentially enabling them to manipulate virtual machines, steal sensitive configuration data, and establish persistent backdoors within the virtualized environment. This vulnerability directly aligns with attack patterns described in the MITRE ATT&CK framework under the T1059.001 technique for command and scripting interpreter, and the T1078.004 technique for valid accounts, as the compromised system can be used to maintain long-term access and lateral movement within the network. The vulnerability also relates to CWE-434 which describes insecure file upload, and represents a significant threat to enterprise security posture given that vCenter servers typically contain sensitive information about virtual infrastructure and are often accessible from external networks.
Organizations affected by CVE-2021-22005 should immediately implement multiple layers of mitigation strategies to address the arbitrary file upload vulnerability. The primary recommendation involves applying the official VMware patches released in vCenter Server 7.0 U1c and 6.7 U3k, which include enhanced file validation and upload restrictions within the Analytics service. Network segmentation should be implemented to restrict access to vCenter Server ports, particularly port 443, limiting exposure to unauthorized networks. Additional mitigations include implementing web application firewalls to monitor and filter file upload requests, disabling unnecessary services such as the Analytics service if not required, and conducting thorough network monitoring for suspicious file upload activities. Security teams should also review and audit existing access controls, implement principle of least privilege for vCenter Server accounts, and establish regular vulnerability scanning procedures to identify similar weaknesses in the virtualization infrastructure. The vulnerability demonstrates the critical importance of proper input validation and file handling in enterprise web applications, and serves as a reminder of the potential consequences when security controls are insufficiently implemented in critical infrastructure components.