CVE-2020-17134 in Windows
Summary
by MITRE • 12/10/2020
, aka 'Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability'. This CVE ID is unique from CVE-2020-17103, CVE-2020-17136.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/29/2025
The Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability represents a critical security flaw in Microsoft's Windows operating systems that allows local attackers to escalate their privileges from standard user level to system level. This vulnerability specifically affects the cloud files mini filter driver component that handles file operations in cloud storage environments, particularly impacting Windows 10 versions 1903 and 1909, as well as Windows Server 2019 and Windows Server 2016. The issue stems from improper validation of input parameters within the kernel-mode driver, creating a path for privilege escalation attacks that can be exploited by malicious actors with local access to a target system. According to the Common Weakness Enumeration catalog, this vulnerability maps to CWE-121, which describes heap-based buffer overflow conditions that can lead to privilege escalation when kernel-mode components fail to properly validate memory operations.
The technical exploitation of this vulnerability occurs through a specific flaw in how the cloud files mini filter driver processes certain file system requests. Attackers can craft malicious input that triggers an improper memory access pattern within the driver's kernel code, allowing them to manipulate memory layout and potentially execute arbitrary code with kernel-level privileges. The vulnerability exists because the driver fails to properly validate the size and content of user-supplied parameters before processing them in kernel space, creating a classic privilege escalation vector. This flaw is particularly dangerous because it operates at the kernel level where malicious code can bypass standard security controls and access all system resources without detection. The ATT&CK framework categorizes this as a privilege escalation technique under T1068, where adversaries leverage software vulnerabilities to gain elevated system privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation, as successful exploitation can enable attackers to install persistent backdoors, modify system files, access sensitive data, and potentially compromise entire network infrastructures. Organizations running affected Windows versions face significant risk of lateral movement attacks, where initial access through this vulnerability can lead to broader network infiltration. The vulnerability's exploitation requires local access to the target system, making it less suitable for remote attacks but still highly dangerous in environments where users have legitimate access to systems. Security researchers have noted that the vulnerability's exploitation can be automated through various attack vectors including malicious file attachments, compromised applications, or social engineering campaigns that trick users into executing malicious code. The Windows Cloud Files Mini Filter Driver vulnerability demonstrates how cloud integration features in operating systems can introduce unexpected security risks when kernel-mode components are not properly hardened against malicious input validation.
Mitigation strategies for this vulnerability include immediate installation of Microsoft security updates that address the specific kernel-mode memory handling flaw in the cloud files mini filter driver. Organizations should prioritize patching all affected Windows 10 and Windows Server versions, particularly those running the cloud storage integration features. Additional defensive measures include implementing strict user access controls, monitoring for unusual file system activity, and deploying endpoint detection and response solutions that can identify potential exploitation attempts. Network segmentation and privilege separation can help limit the impact if exploitation occurs, while regular security assessments should verify that the patching process has been completed successfully across all systems. The vulnerability also underscores the importance of maintaining up-to-date security practices and continuous monitoring for similar issues in other kernel-mode drivers, as similar flaws can exist in other system components that handle user-supplied data.