CVE-2021-1727 in Windows
Summary
by MITRE • 02/26/2021
Windows Installer Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 02/26/2021
This vulnerability involves a critical flaw in the Windows Installer component that allows attackers to escalate privileges from standard user accounts to administrative level access. The issue stems from improper privilege validation within the installer service which fails to properly verify the security context of processes attempting to execute installation operations. When a malicious user or attacker crafts a specially designed installer package or exploits existing installation files, they can manipulate the system to perform actions with elevated privileges without proper authentication or authorization checks.
The technical root cause of this vulnerability lies in the Windows Installer service implementation which does not adequately enforce security boundaries between different privilege levels during installation processes. This flaw typically manifests when the installer service accepts commands or parameters from untrusted sources without validating whether the requesting process has appropriate permissions. The vulnerability can be exploited through various attack vectors including malicious .msi files, compromised installation packages, or by manipulating existing legitimate installation workflows.
From an operational perspective, this privilege escalation vulnerability poses significant risks to enterprise environments where standard user accounts are commonly used for day-to-day operations. Attackers who successfully exploit this vulnerability can gain complete control over affected systems, install persistent backdoors, modify system configurations, access sensitive data, and establish footholds for lateral movement within networks. The impact extends beyond individual systems as compromised installations can serve as launching points for broader attacks against network infrastructure and other connected devices.
Organizations should implement multiple layers of defense to mitigate this vulnerability including immediate deployment of Microsoft security patches, strict application control policies that limit installation permissions, monitoring for suspicious installer activity, and regular security audits of installed software packages. The vulnerability aligns with CWE-276 which addresses improper privileges, and maps to ATT&CK technique T1068 which covers privilege escalation through local exploitation. System administrators should also configure least privilege access controls, implement application whitelisting solutions, and maintain comprehensive logging of installation activities to detect potential exploitation attempts. Regular vulnerability assessments and security awareness training for users can further reduce the attack surface and prevent successful exploitation of this critical weakness in Windows installer services.