CVE-2011-1985 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 validate user-mode input, which allows local users to gain privileges or cause a denial of service (NULL pointer dereference and system crash) via a crafted application, aka "Win32k Null Pointer De-reference Vulnerability."
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Analysis
by VulDB Data Team • 01/21/2025
The CVE-2011-1985 vulnerability represents a critical kernel-mode privilege escalation flaw affecting multiple versions of the Microsoft Windows operating system. This vulnerability resides within the win32k.sys kernel driver which handles graphical user interface components and window management functions. The flaw manifests as improper validation of user-mode input data, creating a pathway for malicious applications to exploit the system's security boundaries and execute arbitrary code with elevated privileges.
The technical nature of this vulnerability stems from a NULL pointer dereference condition within the win32k.sys driver. When a malicious application presents crafted input to the kernel-mode driver, the system fails to properly validate the data before processing it, leading to a situation where a NULL pointer is dereferenced. This condition results in a system crash and potential privilege escalation depending on the execution context and system configuration. The vulnerability specifically affects Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2, and Windows 7 Gold and SP1 versions, making it a widespread concern across multiple Windows platforms.
From an operational perspective, this vulnerability presents significant risks to system security and availability. Local attackers who can execute code on a target system can leverage this flaw to escalate their privileges from standard user level to SYSTEM level access, effectively gaining complete control over the affected machine. The vulnerability can also be exploited to cause denial of service conditions through system crashes, potentially leading to availability disruptions in enterprise environments. The impact extends beyond individual systems as successful exploitation can provide attackers with persistent access to compromised machines, enabling further reconnaissance and lateral movement within networks.
The vulnerability aligns with CWE-476, which describes NULL pointer dereference conditions in software systems. From an adversarial perspective, this flaw maps to several ATT&CK techniques including privilege escalation through kernel exploitation and defense evasion by leveraging system-level access. The attack surface is particularly concerning as it requires no network connectivity and can be exploited through local execution, making it particularly dangerous in environments where user privileges are commonly granted. Organizations should implement immediate mitigations including applying Microsoft security patches, implementing least privilege principles, and monitoring for suspicious system behavior. The vulnerability demonstrates the critical importance of kernel-mode security validation and proper input sanitization in operating system components, as these areas represent the most privileged execution contexts within the Windows ecosystem.