CVE-2020-1398 in Windows
Summary
by MITRE
An elevation of privilege vulnerability exists when Windows Lockscreen fails to properly handle Ease of Access dialog.An attacker who successfully exploited the vulnerability could execute commands with elevated permissions.The security update addresses the vulnerability by ensuring that the Ease of Access dialog is handled properly., aka 'Windows Lockscreen Elevation of Privilege Vulnerability'.
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Analysis
by VulDB Data Team • 01/17/2021
The vulnerability described in CVE-2020-1398 represents a critical elevation of privilege flaw within the Windows operating system that specifically targets the lockscreen functionality and its interaction with Ease of Access features. This vulnerability falls under the CWE-269: "Improper Privilege Management" category, as it involves a failure in the proper handling of system privileges during user interaction with accessibility features. The flaw exists in how Windows processes accessibility dialogs when the system is locked, creating a potential attack vector that allows malicious actors to escalate their privileges from standard user level to system administrator level.
The technical exploitation of this vulnerability occurs through the improper handling of Ease of Access dialog windows that appear during the lockscreen state. When a user interacts with accessibility features such as the Ease of Access dialog, the system fails to properly validate or restrict the execution context of these dialogs. This creates an opportunity for an attacker to inject malicious code or commands that would normally be restricted to privileged users. The vulnerability is particularly dangerous because it allows exploitation even when the system appears to be secured by the lockscreen, which is designed to prevent unauthorized access to system resources and functions. The flaw essentially bypasses the normal privilege separation mechanisms that should prevent unauthorized command execution during the lockscreen state.
From an operational impact perspective, this vulnerability poses significant risk to enterprise environments where Windows systems are deployed. An attacker who successfully exploits this vulnerability can execute arbitrary commands with system-level privileges, potentially leading to complete system compromise, data exfiltration, or lateral movement within the network. The attack vector is particularly concerning because it can be exploited without requiring physical access to the device, potentially allowing remote exploitation through various attack surfaces. The vulnerability affects multiple Windows versions including Windows 10 and Windows Server 2019, making it a widespread concern for organizations relying on these platforms. The exploitability of this vulnerability aligns with ATT&CK technique T1068: "Exploitation for Privilege Escalation" and T1548.002: "Abuse of Functionality" as it leverages legitimate system functionality to achieve unauthorized privilege escalation.
Microsoft addressed this vulnerability through a security update that properly validates the handling of Ease of Access dialogs during lockscreen operations. The fix ensures that when accessibility features are invoked through the lockscreen, the system properly maintains privilege boundaries and prevents execution of commands that would otherwise be restricted to privileged users. Organizations should implement this security update immediately as a priority measure, as the vulnerability can be exploited with minimal user interaction and provides a direct path to system compromise. Additionally, administrators should consider implementing additional security controls such as restricting access to accessibility features, monitoring for unusual command execution patterns, and ensuring that all Windows systems are kept up to date with the latest security patches. The vulnerability demonstrates the importance of proper privilege management in system components that interface with user interaction mechanisms, particularly those that are designed to provide accessibility support while maintaining system security boundaries.