CVE-2016-7238 in Windows
Summary
by MITRE
Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, and 1607, and Windows Server 2016 mishandle caching for NTLM password-change requests, which allows local users to gain privileges via a crafted application, aka "Windows NTLM Elevation of Privilege Vulnerability."
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Analysis
by VulDB Data Team • 09/30/2022
This vulnerability represents a critical privilege escalation flaw in Microsoft Windows operating systems that affects multiple versions including Vista SP2 through Windows 10 1607 and Windows Server 2016. The issue stems from improper handling of NTLM authentication caching mechanisms during password change operations, creating a pathway for local attackers to elevate their privileges from standard user level to system administrator level. The vulnerability is classified under CWE-276 as improper privilege management and aligns with ATT&CK technique T1068 which covers privilege escalation through local exploitation.
The technical root cause involves the Windows NTLM authentication system maintaining cached credentials in a manner that does not properly validate the legitimacy of password change requests. When a user attempts to change their password, the system caches certain authentication tokens that should be invalidated or properly revalidated after the change. However, this caching mechanism fails to properly invalidate the cached credentials, allowing an attacker to exploit this weakness by crafting a malicious application that can manipulate these cached values to gain elevated privileges. The vulnerability specifically impacts the NTLM protocol implementation which is used across various Windows authentication scenarios including local logons and network authentication.
The operational impact of this vulnerability is significant as it allows local users to bypass standard security controls that normally prevent privilege escalation. Attackers can leverage this flaw to execute arbitrary code with system-level privileges without requiring additional exploitation vectors or remote access capabilities. This makes the vulnerability particularly dangerous in environments where users may have legitimate local access to systems but should not possess administrative privileges. The attack requires only local execution capability and does not necessitate network access or complex exploitation techniques, making it accessible to a wide range of threat actors.
Mitigation strategies should focus on immediate patch application as provided by Microsoft through regular security updates and service packs. Organizations should prioritize deployment of the relevant security updates that address the NTLM caching behavior and properly invalidate authentication tokens during password change operations. Additional defensive measures include implementing least privilege principles to minimize the impact of potential exploitation, monitoring for unusual authentication patterns, and ensuring that local user accounts do not have unnecessary administrative privileges. Network segmentation and access controls should also be reviewed to limit the potential attack surface and prevent lateral movement if exploitation occurs. The vulnerability demonstrates the importance of proper credential management and authentication token handling in operating system security implementations.