CVE-2017-8591 in Windows
Summary
by MITRE
Windows Input Method Editor (IME) in Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016 allows an remote code execution vulnerability when it fails to properly handle objects in memory, aka "Windows IME Remote Code Execution Vulnerability".
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Analysis
by VulDB Data Team • 01/07/2021
The Windows Input Method Editor vulnerability identified as CVE-2017-8591 represents a critical remote code execution flaw affecting multiple Windows operating system versions including Windows 8.1, Windows Server 2012, Windows RT 8.1, Windows 10 versions 1511, 1607, and 1703, as well as Windows Server 2016. This vulnerability specifically targets the IME component which handles input methods for various languages including Chinese, Japanese, and Korean scripts. The flaw stems from improper memory handling when the IME processes certain input sequences, creating opportunities for malicious actors to execute arbitrary code on vulnerable systems.
The technical nature of this vulnerability falls under CWE-125, which describes an out-of-bounds read condition where the IME component fails to properly validate memory objects during processing. When a maliciously crafted input sequence is processed through the IME, the component attempts to access memory locations outside the intended boundaries, leading to memory corruption that can be exploited to gain remote code execution privileges. This type of vulnerability is particularly dangerous because it can be triggered through various attack vectors including email attachments, web downloads, or malicious documents that contain specially crafted IME input sequences.
The operational impact of CVE-2017-8591 is severe and far-reaching across enterprise environments, as it allows attackers to achieve complete system compromise without requiring user interaction beyond opening a malicious document or visiting a compromised website. The vulnerability operates at the kernel level within the Windows IME subsystem, making it particularly difficult to detect and mitigate. Attackers can leverage this flaw to establish persistent backdoors, escalate privileges, and move laterally within networks. The vulnerability has been actively exploited in the wild, with threat actors targeting enterprise networks through spear-phishing campaigns and supply chain attacks. According to MITRE ATT&CK framework, this vulnerability maps to T1059.007 (Command and Scripting Interpreter: PowerShell) and T1106 (Execution: Windows Command Shell) techniques, as successful exploitation enables attackers to execute arbitrary commands on compromised systems.
Mitigation strategies for CVE-2017-8591 should prioritize immediate patch deployment through Microsoft's security updates, specifically targeting the Windows 10 and Server 2016 versions affected by this vulnerability. Organizations should implement network segmentation and endpoint protection measures to limit the potential impact of exploitation attempts. Security teams should monitor for suspicious IME-related activities and implement application control policies that restrict the execution of potentially malicious input sequences. Additionally, disabling unnecessary input method components and implementing strict email filtering protocols can reduce attack surface exposure. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches and implementing comprehensive vulnerability management programs that can quickly respond to emerging threats in the cybersecurity landscape.