CVE-2021-1697 in Windows
Summary
by MITRE • 01/13/2021
Windows InstallService Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 10/09/2024
The Windows InstallService elevation of privilege vulnerability represents a critical security flaw in Microsoft Windows operating systems that allows unauthenticated attackers to escalate their privileges from standard user level to SYSTEM level. This vulnerability specifically affects the Windows Installer service which is responsible for managing software installations and updates on Windows systems. The flaw exists in the way the service handles certain installation requests and validates user permissions, creating an opportunity for malicious actors to exploit the system's trust model and gain elevated privileges without proper authentication. The vulnerability impacts multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it particularly dangerous in enterprise environments where these systems are prevalent.
Technical exploitation of CVE-2021-1697 occurs through a privilege escalation mechanism that leverages improper access control within the Windows Installer service. The vulnerability stems from a lack of proper input validation and privilege checking when processing installation requests, allowing attackers to manipulate installation parameters to bypass standard security restrictions. This flaw enables attackers to execute arbitrary code with SYSTEM privileges, effectively granting them complete control over the affected system. The vulnerability is classified under CWE-276 as improper privilege management, specifically involving inadequate access control mechanisms. Attackers typically exploit this by creating malicious installation packages or manipulating existing installation processes to trigger the vulnerable code path, which then executes with elevated privileges due to insufficient permission validation.
The operational impact of this vulnerability extends beyond individual system compromise to potentially affect entire network infrastructures, particularly in enterprise environments where multiple Windows systems are deployed. Organizations running affected Windows versions face significant risk of unauthorized access, data breaches, and potential lateral movement within their networks. The vulnerability can be exploited remotely in certain configurations, making it particularly dangerous for systems exposed to untrusted networks or the internet. Security researchers have noted that this vulnerability can be chained with other exploits to create more sophisticated attack vectors, potentially leading to complete system compromise. The vulnerability's impact is further amplified by the fact that many organizations may not have immediate visibility into which systems are affected, particularly in large enterprise environments with diverse operating system deployments.
Mitigation strategies for CVE-2021-1697 primarily involve applying Microsoft's security patches and updates as soon as they become available, which address the underlying privilege escalation flaw in the Windows Installer service. Organizations should prioritize patch management processes to ensure all affected Windows systems receive the necessary updates promptly. Additional defensive measures include implementing strict access controls and privilege management policies, disabling unnecessary installation services where possible, and monitoring for suspicious installation activities. Network segmentation and the principle of least privilege should be enforced to limit the potential impact of successful exploitation. Security teams should also consider implementing endpoint detection and response solutions that can identify anomalous installation patterns or privilege escalation attempts. The vulnerability aligns with ATT&CK technique T1068 which covers privilege escalation through local exploitation, and organizations should incorporate these mitigation strategies into their overall security posture to defend against this and similar vulnerabilities.