CVE-2010-3940 in Windows
Summary
by MITRE
Double free vulnerability in win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7 allows local users to gain privileges via a crafted application, aka "Win32k PFE Pointer Double Free Vulnerability."
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Analysis
by VulDB Data Team • 10/07/2021
The CVE-2010-3940 vulnerability represents a critical double free error in the win32k.sys kernel-mode driver component of Microsoft Windows operating systems. This flaw exists within the Windows kernel-mode subsystem responsible for handling graphical user interface elements and window management functions. The vulnerability specifically affects multiple Windows versions including XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, as well as Windows 7. The double free condition occurs when the win32k.sys driver improperly handles memory allocation and deallocation processes, creating a scenario where the same memory block can be freed twice. This type of vulnerability falls under the CWE-415 category of double free conditions, which is a well-documented memory safety issue that can lead to arbitrary code execution. The vulnerability is particularly dangerous because it operates at kernel level, where the privilege escalation potential is maximal. When exploited, this vulnerability allows local attackers to execute arbitrary code with kernel-level privileges, effectively bypassing system security mechanisms and gaining complete control over the affected system. The attack vector requires a local user to run a specially crafted application that triggers the vulnerable code path in win32k.sys through improper handling of windowing system objects.
The technical exploitation of CVE-2010-3940 leverages the inherent weakness in the memory management routines of the win32k.sys driver by manipulating the pointer references used for window and graphics object handling. The vulnerability stems from the driver's failure to properly validate and manage memory pointers during the processing of user-mode applications that interact with the graphical subsystem. When a malicious application sends crafted window messages or graphics operations to the kernel, it can cause the win32k.sys driver to free the same memory block twice, leading to heap corruption. This heap corruption can then be manipulated by an attacker to overwrite critical data structures or function pointers, ultimately allowing for privilege escalation. The attack follows the typical pattern of heap-based exploitation where the double free creates a predictable memory layout that can be leveraged to achieve code execution. According to the ATT&CK framework, this vulnerability maps to T1068 (Local Privilege Escalation) and T1059 (Command and Scripting Interpreter) as attackers would need to execute commands with elevated privileges to fully exploit the system. The exploitation process requires local access to the target system, making it a local privilege escalation vulnerability rather than a remote attack vector. The vulnerability's impact is severe because the win32k.sys driver is essential for all graphical operations in Windows, making the exploitation path accessible through normal user interactions with the graphical interface.
The operational impact of CVE-2010-3940 extends beyond simple privilege escalation to encompass complete system compromise and potential lateral movement within network environments. Once an attacker successfully exploits this vulnerability, they gain kernel-level access that allows them to bypass all standard Windows security controls including user access controls, file permissions, and application whitelisting mechanisms. The compromised system becomes a potential foothold for further attacks, including data exfiltration, credential harvesting, and deployment of additional malware. Organizations running affected Windows versions are particularly vulnerable since the exploit can be triggered through legitimate user applications, making detection difficult and the attack surface broad. The vulnerability's presence in multiple Windows versions means that enterprises with mixed operating system environments face significant risk across their entire infrastructure. Security professionals must consider that exploitation of this vulnerability can occur through seemingly benign applications that interact with the graphical subsystem, potentially including legitimate business applications or even system utilities. The vulnerability's classification as a local privilege escalation issue means that attackers who already have user-level access to a system can leverage this flaw to gain complete system control, making it a critical concern for organizations with compromised accounts or insider threats. This vulnerability aligns with ATT&CK techniques that involve privilege escalation through kernel-mode exploitation, where attackers can manipulate system-level components to achieve persistent access and avoid detection by traditional security measures.
Mitigation strategies for CVE-2010-3940 require immediate patching of affected systems through Microsoft security updates, as the vulnerability has been addressed in subsequent security releases. Organizations should prioritize patch management for all affected Windows versions, particularly those running legacy operating systems where patching might be more challenging. System administrators should implement additional security controls including disabling unnecessary graphical services, implementing strict application whitelisting policies, and monitoring for suspicious graphical subsystem activity. The vulnerability's exploitation requires local access, so network segmentation and user access controls can help limit the potential impact. Security monitoring should focus on detecting unusual memory allocation patterns or kernel-mode activity that might indicate exploitation attempts. Additionally, organizations should consider implementing exploit prevention technologies such as Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) to make exploitation more difficult. Regular security audits should verify that all systems are properly updated and that no vulnerable versions remain in production environments. The vulnerability's impact on legacy systems highlights the importance of maintaining up-to-date security patches and considering migration to supported Windows versions that have better security protections against such kernel-mode exploits. Organizations should also develop incident response procedures specifically addressing kernel-mode exploit scenarios, as these attacks can be particularly difficult to detect and remediate due to their low-level system access capabilities.