CVE-2011-1887 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."
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Analysis
by VulDB Data Team • 01/21/2025
The CVE-2011-1887 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 with various service packs, and Windows 7. The flaw manifests when a malicious application triggers a NULL pointer dereference within the win32k.sys driver, allowing local attackers to elevate their privileges from standard user level to system level access. This vulnerability operates through a distinct code path compared to other issues referenced in MS11-054, making it particularly concerning for security professionals who must address multiple overlapping vulnerabilities simultaneously.
The technical exploitation of this vulnerability relies on the manipulation of kernel-mode driver functions that handle graphics and user interface operations. When a crafted application executes code that causes the win32k.sys driver to attempt to dereference a NULL pointer, the system experiences an unexpected state that can be leveraged by malicious actors. The vulnerability stems from inadequate input validation within the driver's handling of user-mode applications that interact with graphics subsystems, particularly those involving window management operations and GDI (Graphics Device Interface) calls. This type of flaw falls under CWE-476, which specifically addresses NULL pointer dereference conditions in software systems, and represents a classic example of a kernel-mode privilege escalation vulnerability.
The operational impact of CVE-2011-1887 is severe and far-reaching, as successful exploitation grants attackers complete system control without requiring network access or complex attack vectors. Local users who can execute malicious code on a vulnerable system can immediately escalate their privileges to SYSTEM level, enabling them to bypass all security controls, modify system files, install malware, and access sensitive data. The vulnerability's exploitation requires only local execution capabilities, making it particularly dangerous in environments where users may have legitimate access to systems but could be compromised through social engineering or other attack vectors. From an adversary perspective, this vulnerability aligns with ATT&CK technique T1068, which describes privilege escalation through local exploitation, and represents a common target for attackers seeking to establish persistent access or move laterally within compromised networks.
Mitigation strategies for CVE-2011-1887 primarily involve applying the relevant Microsoft security patches released as part of MS11-054, which address the specific NULL pointer dereference issue in win32k.sys. System administrators should prioritize deployment of these patches across all affected Windows systems, particularly in enterprise environments where the risk of exploitation is highest. Additional protective measures include implementing user account control policies, restricting local user privileges, and monitoring for suspicious application behavior that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of kernel-mode security and highlights the necessity of maintaining up-to-date system patches, as this flaw could be exploited by attackers with minimal technical skill to achieve complete system compromise. Organizations should also consider implementing application whitelisting policies and monitoring for abnormal graphics driver behavior as part of their defense-in-depth strategies.