CVE-2010-3939 in Windows
Summary
by MITRE
Buffer overflow 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 vectors related to improper memory allocation for copies from user mode, aka "Win32k Buffer Overflow Vulnerability."
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Analysis
by VulDB Data Team • 10/07/2021
The CVE-2010-3939 vulnerability represents a critical buffer overflow flaw within the win32k.sys kernel-mode driver component of Microsoft Windows operating systems. This vulnerability affects a broad range of Microsoft Windows versions including Windows xp sp2 and sp3, windows server 2003 sp2, windows vista sp1 and sp2, windows server 2008 gold sp2 and r2, and windows 7. The flaw resides in the kernel-mode drivers that handle graphical user interface operations, making it particularly dangerous as it operates at the most privileged level of the operating system. The vulnerability stems from improper memory allocation practices during copies from user mode to kernel mode, creating conditions where malicious code can overwrite adjacent memory locations. This type of vulnerability falls under the common weakness enumeration category CWE-121, which deals with stack-based buffer overflow conditions, and specifically relates to CWE-125 which addresses out-of-bounds read vulnerabilities. The attack surface is significant as win32k.sys handles critical graphical operations including window management, drawing functions, and user interface rendering components that are essential for normal system operation. The vulnerability is classified under the attack technique category T1068 in the attack tactic framework, which covers local privilege escalation through exploitation of system vulnerabilities.
The technical implementation of this buffer overflow occurs when user-mode applications interact with kernel-mode components through the win32k.sys driver. During these interactions, the driver fails to properly validate the size of data being copied from user space into kernel space, allowing an attacker to provide more data than the allocated buffer can accommodate. This condition creates a situation where adjacent memory locations in kernel space become overwritten, potentially corrupting critical data structures or even allowing code execution within the kernel context. The flaw specifically manifests when processing certain graphical operations that involve copying user-supplied data into kernel buffers without adequate bounds checking. Attackers can exploit this vulnerability by crafting malicious applications that trigger the vulnerable code path, typically through graphical user interface operations that involve window management, drawing, or other win32k.sys functions. The exploitation process involves carefully constructed input data that exceeds the buffer capacity, causing the overflow to overwrite critical kernel memory locations. This type of vulnerability is particularly insidious because it allows local users to escalate privileges from standard user level to kernel level execution, providing complete system compromise. The attack requires local access to the system but does not need network connectivity, making it a significant concern for systems where local access is possible.
The operational impact of CVE-2010-3939 extends beyond simple privilege escalation to encompass complete system compromise and potential data exfiltration capabilities. Once successfully exploited, the vulnerability allows attackers to execute arbitrary code with kernel-level privileges, effectively providing them with unrestricted access to all system resources, including the ability to modify or delete any file, access any network connection, or extract sensitive information from memory. The vulnerability affects the stability and security posture of affected systems, as it creates a persistent backdoor that can be used for long-term system compromise. Organizations running vulnerable versions of windows are exposed to significant risk, particularly in environments where local access is possible through legitimate user accounts or where users might be tricked into executing malicious code. The impact is particularly severe in enterprise environments where a single compromised system can potentially serve as a foothold for broader network infiltration. The vulnerability's exploitation can also lead to system instability and crashes, as the kernel memory corruption can cause unpredictable behavior in system operations. Additionally, the vulnerability's presence in multiple windows versions means that organizations must carefully assess their entire fleet of systems to ensure complete protection against this threat vector.
Mitigation strategies for CVE-2010-3939 focus on both immediate remediation and long-term security hardening measures. Microsoft addressed this vulnerability through security updates released in the 2010 timeframe, and organizations should ensure all affected systems are patched with the latest security updates from microsoft. The primary defense mechanism involves applying the official microsoft security patches that correct the buffer overflow condition in win32k.sys. System administrators should also implement additional security controls including disabling unnecessary graphical user interface operations, limiting user privileges where possible, and monitoring for suspicious kernel-mode activity. The vulnerability's exploitation requires local access, so restricting local system access and implementing strong user authentication measures can significantly reduce the attack surface. Network segmentation and access controls should be implemented to prevent lateral movement if a system is compromised. Organizations should also consider implementing endpoint protection solutions that can detect and prevent exploitation attempts targeting kernel-mode vulnerabilities. Regular security assessments and vulnerability scanning should be conducted to identify any remaining vulnerable systems within the network infrastructure. The mitigation approach aligns with the principle of least privilege and defense in depth strategies recommended in cybersecurity frameworks, ensuring that even if one layer of defense is breached, additional protective measures remain effective against exploitation attempts.