CVE-2012-1864 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 "String Atom Class Name Handling Vulnerability," a different vulnerability than CVE-2012-1865.
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Analysis
by VulDB Data Team • 03/25/2021
The vulnerability identified as CVE-2012-1864 represents a critical privilege escalation flaw within the Windows kernel-mode driver subsystem, specifically affecting the win32k.sys component that manages user-mode input processing for graphical user interface elements. This vulnerability operates through a sophisticated mechanism where the kernel-mode driver fails to properly validate and sanitize user-mode input data before processing it within kernel space, creating a pathway for malicious applications to execute arbitrary code with elevated privileges. The flaw manifests in the handling of string atom class names, which are used to manage window class names and other graphical elements in the Windows operating system, making it particularly dangerous as it leverages fundamental GUI subsystem operations that are frequently accessed during normal system operation.
The technical exploitation of this vulnerability involves a local attacker crafting a malicious application that can manipulate the string atom class name handling mechanism within win32k.sys, allowing the attacker to corrupt kernel memory structures and ultimately execute code with system-level privileges. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and more specifically relates to improper input validation in kernel-mode drivers. The vulnerability operates at the intersection of user-mode and kernel-mode execution contexts, where the kernel driver receives untrusted input from user applications without adequate sanitization, creating a classic privilege escalation vector. The flaw is particularly insidious because it requires no network connectivity and can be exploited through local execution, making it a preferred target for attackers seeking persistent system compromise.
The operational impact of CVE-2012-1864 extends beyond simple privilege escalation, as successful exploitation can lead to complete system compromise and persistent backdoor access. Attackers can leverage this vulnerability to install rootkits, modify system files, establish persistent network connections, and exfiltrate sensitive data without detection. The vulnerability affects a broad range of Windows operating systems including legacy platforms that were still in use during the time of discovery, making it particularly dangerous in enterprise environments where older systems may not have been properly updated. From an adversary perspective, this vulnerability aligns with ATT&CK technique T1068, which describes "Exploitation for Privilege Escalation," and T1547, covering "Boot or Logon Autostart Execution,' as successful exploitation enables attackers to establish persistent access. The vulnerability's exploitation typically requires minimal user interaction beyond executing a malicious application, making it particularly effective in social engineering campaigns or when attackers have already gained initial access to a system through other means.
Mitigation strategies for CVE-2012-1864 focus on both immediate system hardening and long-term remediation approaches. Microsoft addressed this vulnerability through security updates that improved input validation within the win32k.sys driver, requiring all affected systems to be patched immediately. Organizations should implement comprehensive patch management policies that prioritize critical security updates and maintain detailed inventory of all systems running affected versions of Windows. Additional mitigations include implementing application whitelisting policies, disabling unnecessary user privileges, and monitoring for unusual kernel-mode activity that might indicate exploitation attempts. Security professionals should also consider deploying kernel-mode exploit detection tools and maintaining detailed system baseline configurations to quickly identify any modifications that might indicate successful exploitation of this vulnerability. The vulnerability demonstrates the critical importance of kernel-mode security and the need for robust input validation mechanisms throughout the operating system's execution environment, as flaws in these core components can provide attackers with the ultimate path to system compromise.