CVE-2017-8565 in Windows
Summary
by MITRE
Windows PowerShell in Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, 1703, and Windows Server 2016 allows a remote code execution vulnerability when PSObject wraps a CIM Instance, aka "Windows PowerShell Remote Code Execution Vulnerability".
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Analysis
by VulDB Data Team • 12/31/2020
This vulnerability resides in the Windows PowerShell component of multiple Windows operating systems, specifically affecting versions including Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, 1703, and Windows Server 2016. The flaw manifests when PowerShell's PSObject handles CIM (Common Information Model) instances, creating a remote code execution vector that adversaries can exploit to gain unauthorized access to affected systems. The vulnerability is categorized under CWE-121, which describes a buffer overflow condition where data is written beyond the boundaries of a fixed-length buffer, representing a critical security weakness in software design that can lead to arbitrary code execution.
The technical mechanism behind this vulnerability involves the improper handling of CIM instances within PowerShell's object model. When PowerShell processes CIM instances through PSObject, it fails to properly validate or sanitize the data structure, allowing maliciously crafted CIM objects to trigger memory corruption. This memory corruption occurs during the object wrapping process where PowerShell attempts to create a PSObject representation of the CIM instance. Attackers can leverage this by crafting specially designed CIM instances that, when processed by PowerShell, cause the execution flow to jump to attacker-controlled code. The vulnerability specifically relates to the way PowerShell handles object marshaling and memory allocation when dealing with complex object structures, creating opportunities for attackers to manipulate the execution environment through carefully constructed input data.
The operational impact of this vulnerability is severe as it enables remote code execution without requiring authentication, making it particularly dangerous in enterprise environments where PowerShell is widely used for administrative tasks and automation. An attacker could exploit this vulnerability by delivering a malicious CIM instance through various attack vectors including email attachments, web-based attacks, or compromised network services. Once successfully exploited, the vulnerability allows adversaries to execute arbitrary code with the privileges of the PowerShell process, which typically runs with elevated permissions in many enterprise environments. This could lead to complete system compromise, data exfiltration, lateral movement within the network, and persistence mechanisms that persist across system reboots. The vulnerability affects both server and client operating systems, expanding the potential attack surface significantly.
Mitigation strategies for this vulnerability include applying the official Microsoft security updates that address the specific memory handling issues in PowerShell's CIM instance processing. Organizations should prioritize patching all affected systems, particularly those running Windows Server 2008 and Windows 7, which are no longer supported by Microsoft but may still be in use in legacy environments. Additional protective measures include implementing strict PowerShell execution policies that limit script execution, disabling unnecessary PowerShell features, and monitoring for suspicious PowerShell activities through security information and event management systems. Network segmentation and access controls should be enforced to limit the potential impact of successful exploitation, while security teams should implement behavioral monitoring to detect anomalous PowerShell usage patterns that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1059.001, which covers PowerShell command and script execution, making it a critical concern for organizations monitoring for adversary behavior within their networks.