CVE-2017-11940 in Windows
Summary
by MITRE
The Microsoft Malware Protection Engine running on Microsoft Forefront and Microsoft Defender on Windows 7 SP1, Windows 8.1, Windows RT 8.1, Windows 10 Gold, 1511, 1607, and 1703, 1709 and Windows Server 2016, Windows Server, version 1709, Microsoft Exchange Server 2013 and 2016, does not properly scan a specially crafted file leading to remote code execution. aka "Microsoft Malware Protection Engine Remote Code Execution Vulnerability". This is different than CVE-2017-11937.
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Analysis
by VulDB Data Team • 01/26/2021
The CVE-2017-11940 vulnerability represents a critical remote code execution flaw within Microsoft's Malware Protection Engine, which forms the core scanning component of various Microsoft security products including Forefront and Windows Defender. This vulnerability affects a broad range of Microsoft operating systems and server products, specifically targeting Windows 7 SP1, Windows 8.1, Windows RT 8.1, Windows 10 versions 1511, 1607, 1703, and 1709, along with Windows Server 2016 and Windows Server version 1709, as well as Microsoft Exchange Server 2013 and 2016. The vulnerability stems from improper handling of specially crafted files during the scanning process, creating a pathway for attackers to execute arbitrary code on affected systems without direct user interaction.
The technical flaw manifests in the way the Malware Protection Engine processes certain file formats, particularly those that contain malformed or specially constructed elements that trigger unexpected behavior in the scanning algorithm. This vulnerability is classified under CWE-129, which deals with insufficient validation of the length or size of input data, and more specifically relates to CWE-119, which addresses weaknesses in memory management that can lead to buffer overflows and arbitrary code execution. The engine's failure to properly validate file structures during analysis creates a condition where maliciously crafted input can cause the scanning process to execute unintended code sequences, effectively bypassing traditional security controls.
The operational impact of this vulnerability is severe as it allows attackers to achieve remote code execution on systems without requiring authentication or user interaction, making it particularly dangerous in enterprise environments where multiple systems may be simultaneously affected. The vulnerability's exploitation can lead to complete system compromise, data theft, lateral movement within networks, and establishment of persistent backdoors. Security researchers have noted that this vulnerability can be exploited through various attack vectors including email attachments, web downloads, and file sharing protocols, with the potential for widespread impact across organizations that rely on Microsoft's security products for malware protection. The fact that this vulnerability affects both client and server operating systems means that organizations may face exploitation across their entire infrastructure, from endpoint devices to critical server environments.
Mitigation strategies for CVE-2017-11940 should include immediate deployment of Microsoft's security patches, which address the underlying file validation issues within the Malware Protection Engine. Organizations should also implement network segmentation and monitoring to detect potential exploitation attempts, as well as maintain updated threat intelligence feeds that can identify malicious files targeting this vulnerability. The ATT&CK framework categorizes this vulnerability under T1059, which covers command and scripting interpreter techniques, as exploitation typically involves execution of malicious code through compromised systems. Additionally, implementing additional security controls such as application whitelisting, email filtering, and network-based intrusion detection systems can provide defense-in-depth measures. Organizations should also conduct thorough vulnerability assessments to identify systems that may be running outdated versions of the Malware Protection Engine or that have not received the applicable security updates, as the vulnerability affects multiple product lines and versions, requiring comprehensive patch management across all affected platforms.