CVE-2017-8622 in Windows
Summary
by MITRE
Windows Subsystem for Linux in Windows 10 1703 allows an elevation of privilege vulnerability when it fails to properly handle handles NT pipes, aka "Windows Subsystem for Linux Elevation of Privilege Vulnerability".
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Analysis
by VulDB Data Team • 01/07/2021
The Windows Subsystem for Linux (WSL) represents a significant security vulnerability documented in CVE-2017-8622, which affects Windows 10 version 1703 and potentially other variants. This vulnerability stems from improper handle management within NT pipes, creating a critical elevation of privilege flaw that could allow attackers to escalate their privileges from standard user level to system level access. The subsystem operates by translating linux system calls into windows system calls, enabling linux applications to run natively on windows environments, yet this translation layer presents a dangerous weakness in the handle management mechanisms.
The technical flaw manifests when WSL fails to properly validate or handle NT pipe objects, which are essential for inter-process communication between the linux subsystem and the underlying windows kernel. This improper handling creates a scenario where malicious code can manipulate pipe handles to gain unauthorized access to system resources. The vulnerability specifically relates to how WSL manages the security descriptors and access control lists associated with these pipe objects, allowing potential attackers to exploit the subsystem's trust model and escalate their privileges without proper authentication. This weakness exists within the core architecture of how WSL interfaces with windows kernel components, particularly in the way it processes handle inheritance and access permissions.
The operational impact of this vulnerability is severe and far-reaching, as it enables attackers to bypass standard windows security mechanisms and execute code with system-level privileges. An attacker who successfully exploits this vulnerability could gain complete control over the affected system, potentially leading to data theft, system compromise, or further lateral movement within a network. The vulnerability affects all versions of Windows 10 that include WSL, making it particularly dangerous given the widespread adoption of this feature. The attack surface is broad since WSL is enabled by default on many systems, and the privilege escalation occurs at the kernel level, making detection and prevention extremely challenging.
This vulnerability aligns with CWE-264, which addresses permissions, privileges, and access control issues, specifically focusing on improper handling of access control mechanisms. From an ATT&CK perspective, this vulnerability maps to privilege escalation techniques and specifically relates to T1068, which covers local privilege escalation through kernel exploits, and potentially T1059, which involves executing malicious code through command-line interfaces. The attack vector typically involves crafting malicious commands or applications that leverage the pipe handle vulnerability to gain elevated privileges. Microsoft addressed this issue through security updates that corrected the handle validation mechanisms and improved the security descriptors associated with NT pipes in the WSL subsystem, requiring users to apply the latest patches to mitigate the risk.
Organizations should implement comprehensive monitoring for suspicious WSL activity and ensure all Windows 10 systems are updated with the latest security patches. The vulnerability highlights the importance of secure handle management in operating system components and underscores the risks associated with integrating subsystems that bridge different operating system security models. Additionally, administrators should consider disabling WSL if it is not required for business operations, as a defensive measure against potential exploitation of this and similar vulnerabilities.