CVE-2012-1890 in Windows
Summary
by MITRE
win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 does not properly handle keyboard-layout files, which allows local users to gain privileges via a crafted application, aka "Keyboard Layout Vulnerability."
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Analysis
by VulDB Data Team • 03/26/2021
The vulnerability identified as CVE-2012-1890 represents a critical privilege escalation flaw within the Windows kernel-mode driver component known as win32k.sys. This issue affects multiple versions of the Windows operating system including legacy platforms such as Windows xp service pack 2 and 3, windows server 2003 service pack 2, windows vista service pack 2, windows server 2008 service pack 2 and r2, and windows 7 gold and service pack 1. The vulnerability stems from improper handling of keyboard layout files within the kernel-mode environment, creating a pathway for local attackers to elevate their privileges from standard user level to system level access. The flaw specifically resides in how the win32k.sys driver processes keyboard layout information, which is a fundamental component of the windows graphical subsystem responsible for managing input device interactions.
The technical exploitation of this vulnerability occurs when a malicious application crafts and loads a specially constructed keyboard layout file that triggers a buffer overflow or memory corruption condition within the win32k.sys driver. This improper handling of keyboard layout files allows an attacker to manipulate the driver's memory management routines, potentially leading to arbitrary code execution in kernel space. The vulnerability is classified as a local privilege escalation issue because it requires an attacker to already have a user account on the system, but once exploited, it provides complete system compromise. The attack vector is particularly concerning because keyboard layout files are commonly used system components that can be loaded through normal user operations, making the exploitation relatively straightforward and difficult to detect.
The operational impact of CVE-2012-1890 is severe and far-reaching across enterprise environments, particularly affecting organizations running supported but older windows versions that may not have received timely security updates. Successful exploitation grants attackers complete system control, enabling them to install malicious software, modify system files, access sensitive data, and potentially establish persistence mechanisms. The vulnerability's classification under cwe-121 (stack-based buffer overflow) and cwe-125 (out-of-bounds read) demonstrates its fundamental nature as a memory safety issue that can be exploited for privilege escalation. From an att&ck framework perspective, this vulnerability maps to privilege escalation techniques and can be used to achieve initial access or maintain persistence within compromised systems. The vulnerability also represents a significant concern for compliance and security auditing, as it allows attackers to bypass traditional user-level access controls and gain administrative privileges without requiring external network access or complex attack chains.
Mitigation strategies for CVE-2012-1890 should prioritize immediate patch deployment through microsoft security updates, as the vulnerability has been addressed through official microsoft security bulletins. Organizations should implement additional security controls including restricting user privileges, disabling unnecessary keyboard layout file loading capabilities, and monitoring for suspicious keyboard layout file modifications. The principle of least privilege should be enforced to minimize potential impact, and system administrators should conduct regular vulnerability assessments to identify and remediate similar issues. Network segmentation and endpoint protection solutions can provide additional layers of defense, though they cannot prevent exploitation of this kernel-level vulnerability. Organizations should also consider implementing application whitelisting policies to prevent unauthorized applications from loading malicious keyboard layout files, as this approach directly addresses the attack vector. Regular security awareness training should emphasize the risks of executing untrusted applications that may attempt to exploit such kernel vulnerabilities.