CVE-2011-1888 in Windows
Summary
by MITRE
win32k.sys in the kernel-mode drivers in Microsoft Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 allows local users to gain privileges via a crafted application that triggers a NULL pointer dereference, a different vulnerability than other CVEs listed in MS11-054, aka "Win32k Null Pointer De-reference Vulnerability."
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 11/14/2021
The CVE-2011-1888 vulnerability represents a critical privilege escalation flaw within the Windows kernel-mode driver subsystem, specifically targeting the win32k.sys component that manages user interface elements and graphics rendering. This vulnerability exists in multiple Windows versions including Vista SP1 and SP2, Windows Server 2008 Gold, SP2, R2, and R2 SP1, as well as Windows 7 Gold and SP1, making it one of the most widespread kernel-level exploits in the Windows ecosystem. The flaw manifests when a malicious application triggers a NULL pointer dereference condition within the win32k.sys driver, which operates in kernel mode and handles critical system functions including window management, graphics rendering, and user input processing. This particular vulnerability is distinct from other issues catalogued in MS11-054, indicating it operates through a separate code path and exploitation vector despite being part of the same broader security update cycle.
The technical implementation of this vulnerability stems from improper input validation within the win32k.sys driver, which fails to properly handle certain user-mode inputs that ultimately reach kernel space. When a crafted application sends malformed parameters to the graphics subsystem through legitimate Windows APIs, the driver attempts to access a NULL pointer that has not been properly initialized or validated, resulting in an immediate system crash or more critically, allowing privilege escalation. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions in software development, where applications fail to check for null values before dereferencing pointers. The kernel-mode execution context means that successful exploitation can elevate a local user account to SYSTEM level privileges, effectively granting complete control over the affected system.
The operational impact of CVE-2011-1888 is severe and far-reaching, as it enables local privilege escalation without requiring any network connectivity or complex attack vectors. Attackers can leverage this vulnerability through a simple local application that triggers the malformed input conditions, making it particularly dangerous in environments where users have local access to systems. The vulnerability's exploitation can result in complete system compromise, data exfiltration, persistent backdoor installation, and further lateral movement within network environments. Organizations running affected Windows versions are particularly vulnerable as the flaw exists in core system drivers that handle essential user interface functions, meaning any user interaction with graphics-intensive applications or even standard desktop operations could potentially trigger the exploit. This makes the vulnerability extremely difficult to monitor and detect in production environments where legitimate applications frequently interact with the graphics subsystem.
Mitigation strategies for CVE-2011-1888 primarily involve applying the relevant Microsoft security updates that address the underlying kernel-mode driver vulnerability. Organizations should prioritize immediate deployment of the security patches released as part of MS11-054, which specifically target this win32k.sys NULL pointer dereference issue. Additionally, implementing security measures such as user account control restrictions, limiting local user privileges, and monitoring for unusual kernel-mode activity can help reduce the attack surface. System administrators should also consider disabling unnecessary graphics rendering features and restricting access to potentially malicious applications that could trigger the vulnerability. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation through kernel exploits and local execution, with the attack chain typically beginning with initial access through a compromised local application or user account, followed by exploitation of the kernel vulnerability to achieve SYSTEM level control. Regular vulnerability assessments and security monitoring should focus on identifying applications that interact with graphics APIs and kernel-mode drivers to prevent exploitation of similar vulnerabilities.