CVE-2012-1866 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 user-mode input passed to kernel mode for driver objects, which allows local users to gain privileges via a crafted application, aka "Clipboard Format Atom Name Handling Vulnerability."
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Analysis
by VulDB Data Team • 03/25/2021
The vulnerability identified as CVE-2012-1866 represents a critical privilege escalation flaw within the Windows kernel-mode driver subsystem, specifically within the win32k.sys component that manages user interface elements including clipboard functionality. This vulnerability resides in the kernel-mode drivers of multiple Windows operating systems including Windows xp sp2 and sp3, windows server 2003 sp2, windows vista sp2, windows server 2008 sp2 and r2, and windows 7 gold and sp1, making it a widespread concern across the windows ecosystem. The flaw manifests when the system processes user-mode input that is passed to kernel mode for driver objects, creating a dangerous condition where malicious applications can manipulate the kernel execution flow.
The technical exploitation of this vulnerability occurs through improper handling of clipboard format atom name data structures during the interaction between user-mode applications and kernel-mode drivers. When a crafted application attempts to register or manipulate clipboard format atom names, the win32k.sys driver fails to properly validate or sanitize the input parameters before processing them in kernel space. This improper input validation creates a buffer overflow condition or arbitrary code execution opportunity that can be leveraged by local attackers to execute malicious code with kernel-level privileges. The vulnerability specifically targets the clipboard functionality and atom name handling mechanisms within the windows user interface subsystem, making it particularly dangerous as it can be triggered through normal user interaction with clipboard operations.
The operational impact of this privilege escalation vulnerability is severe and far-reaching, as local users who can execute arbitrary code on a target system can leverage this flaw to elevate their privileges from standard user level to system level administrative access. This allows attackers to bypass normal security controls, install malware, modify system files, disable security features, and ultimately gain complete control over the affected system. The vulnerability is particularly concerning because it requires no special privileges to exploit, making it accessible to any user who can run applications on the target system. Additionally, the widespread deployment of affected Windows versions means that numerous systems across enterprise networks, government agencies, and individual users could be compromised, creating a significant attack surface for malicious actors.
Mitigation strategies for this vulnerability primarily involve applying the official microsoft security patches released in response to this flaw, which address the improper input validation in the win32k.sys driver component. System administrators should prioritize immediate patch deployment across all affected windows systems, particularly in enterprise environments where multiple vulnerable versions exist. Additional protective measures include implementing application whitelisting policies to restrict execution of potentially malicious applications, disabling unnecessary clipboard functionality where possible, and monitoring for suspicious privilege escalation attempts through system logs and security information event management systems. The vulnerability aligns with common weakness enumeration cwe-121, which covers stack-based buffer overflow conditions, and represents a typical example of attack technique t1068 from the attack tactics and techniques framework, specifically targeting privilege escalation through kernel-mode exploitation. Organizations should also consider implementing additional security controls such as user access controls, privilege separation, and regular security assessments to reduce the overall risk exposure from such kernel-level vulnerabilities.