CVE-2015-0078 in Windows
Summary
by MITRE
win32k.sys in the kernel-mode drivers in Microsoft Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 does not properly validate the token of a calling thread, which allows local users to gain privileges via a crafted application, aka "Win32k Elevation of Privilege Vulnerability."
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Analysis
by VulDB Data Team • 04/15/2022
The CVE-2015-0078 vulnerability represents a critical privilege escalation flaw in Microsoft Windows kernel-mode drivers, specifically within the win32k.sys component that manages user interface elements and windowing operations. This vulnerability affects a broad range of Microsoft operating systems including Windows 8, Windows 8.1, Windows Server 2012, Windows Server 2012 R2, Windows RT, and Windows RT 8.1. The flaw resides in how the kernel-mode driver validates thread tokens during system calls, creating an exploitable condition that allows local attackers to elevate their privileges from standard user level to system level access. The vulnerability is particularly concerning because it operates within the kernel space where the most privileged operations occur, making it a prime target for attackers seeking to establish persistent system control.
The technical implementation of this vulnerability stems from inadequate validation of thread tokens within the win32k.sys driver, which is responsible for managing the Windows graphical user interface components including windows, menus, and other user interface elements. When a malicious application attempts to invoke certain kernel-mode functions through the win32k.sys driver, the system fails to properly verify the security context and token credentials of the calling thread. This validation failure creates a path where unprivileged code can manipulate the system's privilege escalation mechanisms, effectively bypassing the normal security boundaries that separate user-mode applications from kernel-mode operations. The vulnerability is classified as a kernel-mode privilege escalation flaw that directly violates fundamental security principles of operating system protection mechanisms.
The operational impact of CVE-2015-0078 is severe and far-reaching, as it provides local attackers with the capability to achieve system-level privileges without requiring physical access or complex exploitation techniques. Once successfully exploited, the vulnerability allows attackers to execute arbitrary code with the highest system privileges, enabling them to install malware, modify system files, disable security features, and establish persistent backdoors. The attack vector is particularly dangerous because it requires only local access to the target system, meaning that an attacker who has already gained user-level access through other means can leverage this vulnerability to escalate their privileges. This makes the vulnerability especially attractive for attackers who have already compromised a system through phishing, social engineering, or other initial access methods, as it provides a straightforward path to complete system takeover.
Mitigation strategies for CVE-2015-0078 primarily focus on applying Microsoft security updates and implementing additional operational security measures. Microsoft released patches through the regular security update cycle that address the specific validation flaw in win32k.sys, and organizations should ensure immediate deployment of the relevant security updates. Additionally, implementing the principle of least privilege, disabling unnecessary user accounts, and maintaining current antivirus signatures can help reduce the attack surface and limit potential exploitation success. From an operational security perspective, organizations should monitor for signs of privilege escalation attempts and implement process monitoring to detect anomalous behavior that might indicate exploitation attempts. The vulnerability aligns with CWE-269, which covers "Improper Privilege Management," and represents a classic example of how kernel-mode flaws can enable elevation of privilege attacks that are difficult to detect and defend against using traditional security measures. This vulnerability also maps to ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation," demonstrating how attackers can leverage system vulnerabilities to gain elevated access rights.