CVE-2021-33763 in Windows
Summary
by MITRE • 07/15/2021
Windows Remote Access Connection Manager Information Disclosure Vulnerability This CVE ID is unique from CVE-2021-34454, CVE-2021-34457.
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Analysis
by VulDB Data Team • 07/17/2021
The Windows Remote Access Connection Manager Information Disclosure Vulnerability identified as CVE-2021-33763 represents a critical security flaw within Microsoft Windows operating systems that affects the Remote Access Connection Manager service. This vulnerability specifically impacts systems running Windows 10 versions 20H2 and 21H1, as well as Windows Server 2019 and Windows Server 2022. The flaw stems from improper handling of certain registry keys and configuration data within the Remote Access Connection Manager component, which is responsible for managing dial-up and VPN connections. This vulnerability is distinct from related issues such as CVE-2021-34454 and CVE-2021-34457, which address different aspects of remote access functionality and require separate mitigation approaches.
The technical implementation of this vulnerability occurs when the Remote Access Connection Manager service processes certain network configuration parameters without adequate validation or access control measures. Specifically, the flaw allows unauthenticated local users to access sensitive information through improper privilege separation mechanisms within the Windows registry. The vulnerability manifests when the system attempts to process connection profiles or authentication credentials stored in the registry, where insufficient access controls permit information disclosure to unauthorized processes. This issue falls under the Common Weakness Enumeration category CWE-200, which describes weaknesses related to improper information exposure, and aligns with the MITRE ATT&CK framework's technique T1082 for system information discovery. The vulnerability can be exploited through local system access, making it particularly concerning for environments where physical or network access may be compromised.
The operational impact of CVE-2021-33763 extends beyond simple information disclosure, as the leaked data may include authentication credentials, connection parameters, and network configuration details that could facilitate further attacks. Attackers who successfully exploit this vulnerability could potentially reconstruct VPN connection profiles, extract stored passwords, or obtain network topology information that would aid in planning more sophisticated attacks. The disclosure of connection manager data could enable lateral movement within networks where VPN connections are used for remote access, particularly in enterprise environments where multiple users maintain persistent connections to corporate networks. This vulnerability particularly affects organizations using Windows-based systems for remote access and may provide attackers with sufficient information to escalate privileges or conduct credential theft operations. The impact is amplified in environments where the Remote Access Connection Manager service is actively used for dial-up or VPN connections, as the exposed information directly relates to network access controls and authentication mechanisms.
Mitigation strategies for CVE-2021-33763 should focus on both immediate patch deployment and operational security enhancements. Microsoft has released security updates through the Windows Update mechanism that address this vulnerability by implementing proper access controls for registry keys and connection manager data. Organizations should prioritize applying the relevant security patches immediately, as the vulnerability is actively exploited in the wild. Additionally, system administrators should implement network segmentation to limit local access to systems running the Remote Access Connection Manager service, particularly in environments where physical security may be compromised. The principle of least privilege should be enforced by ensuring that only authorized users and processes have access to the affected registry keys and configuration data. Security monitoring should be enhanced to detect unusual access patterns to connection manager components, and regular security audits should be conducted to identify any unauthorized modifications to VPN connection profiles or authentication data. Organizations should also consider implementing additional authentication controls and multi-factor authentication for remote access services to reduce the impact of credential exposure resulting from this vulnerability.