CVE-2019-1256 in Windows
Summary
by MITRE
An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory, aka 'Win32k Elevation of Privilege Vulnerability'. This CVE ID is unique from CVE-2019-1285.
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Analysis
by VulDB Data Team • 08/19/2020
The vulnerability identified as CVE-2019-1256 represents a critical elevation of privilege flaw within the Windows operating system that specifically impacts the Win32k.sys kernel-mode driver component. This component serves as the foundational graphics subsystem responsible for managing user interface elements, window management, and graphical object handling within the Windows kernel space. The vulnerability stems from improper memory object handling within this critical system component, creating a pathway for malicious actors to escalate their privileges from standard user level to SYSTEM level access. The flaw exists in the manner in which Win32k processes and manages graphical objects in memory, particularly when dealing with certain object types and their associated memory allocations. This vulnerability is particularly concerning because it operates at the kernel level where malicious code can execute with the highest privileges available to any process, potentially enabling complete system compromise.
The technical exploitation of this vulnerability requires an attacker to first obtain initial access to a target system, typically through social engineering, phishing, or other attack vectors that result in a standard user account. Once the attacker has user-level access, they can leverage the Win32k memory handling flaw to manipulate kernel objects and execute arbitrary code with SYSTEM privileges. The vulnerability specifically relates to how the Win32k.sys driver manages certain graphical object types and their associated memory structures, creating potential for memory corruption that can be exploited to gain unauthorized access to system resources. This type of vulnerability falls under the CWE-119 category of "Improper Access to Memory Location" and represents a classic example of a kernel-mode privilege escalation flaw that allows for complete system compromise. The attack vector typically involves crafting specific graphical operations that trigger the memory handling error, which then allows for code execution in kernel space with elevated privileges.
The operational impact of CVE-2019-1256 extends far beyond simple privilege escalation, as it provides attackers with complete control over affected systems. Once exploited, adversaries can install persistent backdoors, modify system files, access sensitive data, and establish footholds for further network penetration. The vulnerability affects multiple Windows versions including Windows 7, Windows 8.1, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, and Windows Server 2016, making it particularly dangerous for enterprise environments where these operating systems are commonly deployed. Organizations running affected systems face significant risk of data breaches, lateral movement within networks, and potential compromise of critical infrastructure. The vulnerability's exploitation can occur through various attack vectors including malicious software downloads, web-based attacks, or even physical access to systems, making it a comprehensive threat that requires immediate remediation. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and can be used to achieve persistence and maintain access to compromised systems.
Mitigation strategies for CVE-2019-1256 primarily focus on immediate patching of affected systems through Microsoft's security updates, which address the underlying memory handling flaw in the Win32k component. Organizations should prioritize deployment of the relevant security patches and ensure comprehensive testing to prevent service disruptions. Additional defensive measures include implementing application control policies to restrict execution of potentially malicious code, monitoring for unusual system behavior that may indicate exploitation attempts, and maintaining robust endpoint detection and response capabilities. Network segmentation and privileged access controls can help limit the potential impact of successful exploitation attempts, while regular security audits and vulnerability assessments should be conducted to identify and remediate similar vulnerabilities. The vulnerability also underscores the importance of maintaining up-to-date security patches and implementing comprehensive security awareness training to prevent initial compromise through social engineering attacks that might lead to exploitation of such kernel-level vulnerabilities.