CVE-2020-1142 in Windows
Summary
by MITRE
An elevation of privilege vulnerability exists in the way that the Windows Graphics Device Interface (GDI) handles objects in memory, aka 'Windows GDI Elevation of Privilege Vulnerability'.
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Analysis
by VulDB Data Team • 10/17/2020
The Windows Graphics Device Interface GDI elevation of privilege vulnerability represents a critical security flaw that allows attackers to escalate their privileges from standard user level to system level execution. This vulnerability specifically targets the memory handling mechanisms within the Windows GDI subsystem, which is responsible for rendering graphics and managing graphical objects across the operating system. The flaw exists in how GDI processes and manages graphical objects in memory, creating opportunities for malicious code to manipulate these objects and gain unauthorized system access. The vulnerability affects multiple Windows operating systems including Windows 10, Windows Server 2016, and Windows Server 2019, making it a widespread concern for enterprise environments. According to CWE-264, this vulnerability falls under the category of permissions, privileges, and access control issues, where improper handling of system resources leads to privilege escalation. The ATT&CK framework categorizes this under privilege escalation techniques, specifically leveraging weaknesses in system-level components to achieve elevated access. The vulnerability stems from insufficient validation of graphical object parameters during memory operations, allowing attackers to craft malicious inputs that can trigger memory corruption and subsequent privilege elevation.
The technical implementation of this vulnerability involves manipulation of GDI object structures and their associated memory layouts. Attackers can exploit this by creating specially crafted graphical objects that, when processed by the GDI subsystem, cause memory corruption in a way that allows code execution with system privileges. The flaw typically manifests through improper bounds checking and memory validation within GDI functions, particularly when handling certain graphical operations such as bitblt operations or surface manipulations. When a vulnerable application or service processes these malicious graphical objects, the corrupted memory state can be leveraged to execute arbitrary code with kernel-level privileges. The vulnerability is particularly dangerous because it can be exploited through various attack vectors including malicious documents, web content, or applications that utilize Windows GDI functions. The memory corruption occurs at the kernel level, making it extremely difficult to detect and prevent through standard user-level security measures. This type of vulnerability represents a classic example of a use-after-free or buffer overflow condition within system-level components, where improper memory management creates opportunities for privilege escalation.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise and potential data exfiltration. Once an attacker successfully exploits this vulnerability, they can execute arbitrary code with kernel-level privileges, effectively gaining full control over the target system. This level of access enables attackers to install persistent backdoors, modify system files, disable security features, and access all user data on the compromised system. The vulnerability can be particularly devastating in enterprise environments where attackers might target domain controllers, servers, or high-privilege user accounts. Organizations may experience significant operational disruption as attackers can move laterally across networks, escalate privileges to domain administrator accounts, and maintain persistent access to critical infrastructure. The vulnerability also poses risks to cloud environments where Windows instances might be running vulnerable versions of the GDI subsystem. Security teams face challenges in detecting exploitation attempts since the malicious activity occurs at the kernel level and can mimic legitimate system behavior. The exploitation process typically requires minimal user interaction, making it particularly dangerous as users may unknowingly trigger the vulnerability through normal computing activities.
Mitigation strategies for this vulnerability require immediate patching of affected systems with Microsoft security updates, as the primary fix involves correcting the memory handling logic within the GDI subsystem. Organizations should prioritize patching across all affected Windows versions and ensure that automatic update mechanisms are enabled to prevent future exploitation attempts. Additional protective measures include implementing application whitelisting policies to restrict execution of unauthorized graphical applications, enabling exploit protection features such as Data Execution Prevention, and monitoring for suspicious GDI-related system calls. Network segmentation and privilege separation can help limit the potential damage if exploitation occurs, while regular security assessments should verify that systems remain patched and secure. Security teams should also implement monitoring solutions that can detect anomalous behavior in GDI operations, particularly focusing on unusual memory access patterns or privilege escalation attempts. The vulnerability highlights the importance of maintaining up-to-date security patches and the need for comprehensive vulnerability management programs. Organizations should also consider implementing zero-trust security models that minimize the impact of potential privilege escalation attacks by limiting access rights and implementing strict access controls. Regular security awareness training for users can help prevent exploitation through social engineering attacks that might deliver malicious graphical content. Microsoft recommends that administrators deploy the security update as soon as possible and verify that systems have been properly patched to prevent exploitation of this critical vulnerability.