CVE-2015-0073 in Windows
Summary
by MITRE
The Windows Registry Virtualization feature in the kernel in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 does not properly restrict changes to virtual stores, which allows local users to gain privileges via a crafted application, aka "Registry Virtualization Elevation of Privilege Vulnerability."
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Analysis
by VulDB Data Team • 04/15/2022
The vulnerability identified as CVE-2015-0073 resides within the Windows Registry Virtualization feature implemented in Microsoft Windows operating systems spanning multiple versions including Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1. This flaw specifically affects the kernel-level implementation of registry virtualization mechanisms that were designed to provide backward compatibility for legacy applications by redirecting registry writes from the standard system locations to virtualized user-specific locations. The vulnerability stems from insufficient access controls and validation mechanisms within the virtual store management system, creating a path for privilege escalation attacks.
The technical flaw manifests when local malicious applications exploit the improper restriction of changes to virtual stores, allowing unauthorized modifications to registry entries that should be protected. The registry virtualization feature typically operates by intercepting registry write operations from applications and redirecting them to virtual stores located in the user profile directory, specifically under the ntuser.dat file. However, the vulnerability occurs because the kernel does not properly validate or restrict access to these virtual stores, enabling a crafted application to manipulate registry entries that would normally require administrator privileges. This weakness creates a scenario where a low-privilege user can effectively elevate their privileges by modifying virtual registry entries that are then processed with elevated permissions, particularly affecting registry keys that control system-level functionality.
The operational impact of this vulnerability is significant as it provides local attackers with a method to escalate privileges from standard user level to administrator level without requiring physical access or sophisticated attack vectors. Attackers can leverage this vulnerability by creating malicious applications that manipulate the virtual registry stores, potentially modifying critical system registry entries that control software installation, service configuration, or security policies. The vulnerability affects systems where registry virtualization is enabled, which is the default behavior for many legacy applications and system components. This privilege escalation capability can lead to complete system compromise, allowing attackers to install malware, modify system configurations, disable security features, or establish persistence mechanisms within the compromised systems. The vulnerability is particularly concerning because it operates at the kernel level and can be exploited through legitimate application execution paths, making detection and prevention challenging.
Mitigation strategies for CVE-2015-0073 should focus on both immediate patching and system hardening measures. Microsoft released security updates that address this vulnerability through kernel-level fixes that properly enforce access controls on virtual stores and restrict unauthorized modifications to registry virtualization mechanisms. Organizations should prioritize applying the relevant security patches as soon as possible, particularly for systems that are not running the latest Windows versions or have not received the specific update addressing this vulnerability. System administrators should also consider disabling registry virtualization for applications that do not require it, though this approach may impact legacy application compatibility. Additional defensive measures include implementing application whitelisting policies, monitoring registry access patterns for suspicious activity, and ensuring that only trusted applications have the ability to modify system registry entries. From a cybersecurity perspective, this vulnerability aligns with CWE-276, which addresses improper privileges, and maps to ATT&CK technique T1068, which covers privilege escalation through local exploitation. The vulnerability demonstrates how seemingly benign system features can create security weaknesses when access controls are not properly implemented at the kernel level, highlighting the importance of comprehensive security testing and validation of system-level components.