CVE-2021-40444
Microsoft MSHTML Remote Code Execution Vulnerability
In short
A flaw in Microsoft's MSHTML rendering engine allows attackers to run malicious code on your computer by tricking you into opening a specially crafted Office document. This is dangerous because Office files are commonly used and trusted by most people.
Technical detail
MSHTML remote code execution via malicious ActiveX controls embedded in Office documents; attack requires user interaction to open the crafted file. Successful exploitation grants code execution in the security context of the user opening the document, with impact varying based on user privileges.
Summary generated and translated by AI from the official description.
<p>Microsoft is investigating reports of a remote code execution vulnerability in MSHTML that affects Microsoft Windows. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability by using specially-crafted Microsoft Office documents.</p>
<p>An attacker could craft a malicious ActiveX control to be used by a Microsoft Office document that hosts the browser rendering engine. The attacker would then have to convince the user to open the malicious document. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.</p>
<p>Microsoft Defender Antivirus and Microsoft Defender for Endpoint both provide detection and protections for the known vulnerability. Customers should keep antimalware products up to date. Customers who utilize automatic updates do not need to take additional action. Enterprise customers who manage updates should select the detection build 1.349.22.0 or newer and deploy it across their environments. Microsoft Defender for Endpoint alerts will be displayed as: “Suspicious Cpl File Execution”.</p>
<p>Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs.</p>
<p>Please see the <strong>Mitigations</strong> and <strong>Workaround</strong> sections for important information about steps you can take to protect your system from this vulnerability.</p>
<p><strong>UPDATE</strong> September 14, 2021: Microsoft has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. Please see the FAQ for important information about which updates are applicable to your system.</p>
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L/E:P/RL:O/RC:C
Affected products
Microsoft · Windows 10 Version 1507Microsoft · Windows 10 Version 1607Microsoft · Windows 10 Version 1809Microsoft · Windows 10 Version 1909Microsoft · Windows 10 Version 2004Microsoft · Windows 10 Version 20H2Microsoft · Windows 10 Version 21H1Microsoft · Windows 7Microsoft · Windows 7 Service Pack 1Microsoft · Windows 8.1Microsoft · Windows Server 2008 R2 Service Pack 1Microsoft · Windows Server 2008 R2 Service Pack 1 (Server Core installation)Microsoft · Windows Server 2008 Service Pack 2Microsoft · Windows Server 2008 Service Pack 2Microsoft · Windows Server 2008 Service Pack 2 (Server Core installation)Microsoft · Windows Server 2012Microsoft · Windows Server 2012 R2Microsoft · Windows Server 2012 R2 (Server Core installation)Microsoft · Windows Server 2012 (Server Core installation)Microsoft · Windows Server 2016Microsoft · Windows Server 2016 (Server Core installation)Microsoft · Windows Server 2019Microsoft · Windows Server 2019 (Server Core installation)Microsoft · Windows Server 2022Microsoft · Windows Server version 2004Microsoft · Windows Server version 20H2public PoCs found — 38
githubgithub.com/lockedbyte/CVE-2021-40444★ 1743githubgithub.com/klezVirus/CVE-2021-40444★ 824githubgithub.com/aslitsecurity/CVE-2021-40444_builders★ 168githubgithub.com/Edubr2020/CVE-2021-40444--CABless★ 102githubgithub.com/34zY/Microsoft-Office-Word-MSHTML-Remote-Code-Execution-Exploit★ 65githubgithub.com/k8gege/CVE-2021-40444★ 19githubgithub.com/ozergoker/CVE-2021-40444★ 16githubgithub.com/rfcxv/CVE-2021-40444-POC★ 16githubgithub.com/mansk1es/Caboom★ 11githubgithub.com/kagura-maru/CVE-2021-40444-POC★ 9githubgithub.com/H0j3n/CVE-2021-40444★ 9githubgithub.com/DarkSprings/CVE-2021-40444★ 7githubgithub.com/LazarusReborn/Docx-Exploit-2021★ 5githubgithub.com/fengjixuchui/CVE-2021-40444-docx-Generate★ 4githubgithub.com/vysecurity/CVE-2021-40444★ 3githubgithub.com/bambooqj/CVE-2021-40444_EXP_JS★ 2githubgithub.com/MRacumen/CVE-2021-40444★ 2githubgithub.com/Zeop-CyberSec/word_mshtml★ 1githubgithub.com/k4k4/CVE-2021-40444-Sample★ 1githubgithub.com/khoaduynu/CVE-2021-40444★ 1githubgithub.com/basim-ahmad/Follina-CVE-and-CVE-2021-40444★ 0githubgithub.com/Immersive-Labs-Sec/cve-2021-40444-analysis★ 0githubgithub.com/KnoooW/CVE-2021-40444-docx-Generate★ 0githubgithub.com/jamesrep/cve-2021-40444★ 0githubgithub.com/W1kyri3/Exploit-PoC-CVE-2021-40444-inject-ma-doc-vao-docx★ 0githubgithub.com/Jeromeyoung/MSHTMHell★ 0githubgithub.com/kal1gh0st/CVE-2021-40444_CAB_archives★ 0githubgithub.com/metehangenel/MSHTML-CVE-2021-40444★ 0githubgithub.com/Jeromeyoung/TIC4301_Project★ 0githubgithub.com/tiagob0b/CVE-2021-40444★ 0githubgithub.com/Alexcot25051999/CVE-2021-40444★ 0githubgithub.com/lisinan988/CVE-2021-40444-exp★ 0githubgithub.com/RedLeavesChilde/CVE-2021-40444★ 0githubgithub.com/nvchungkma/CVE-2021-40444-Microsoft-Office-Word-Remote-Code-Execution-★ 0githubgithub.com/hqdat809/CVE-2021-40444★ 0cve_referencepacketstormsecurity.com/files/167317/Microsoft-Office-MSDT-Follina-Proof-Of-Concept.htmlunverifiedcve_referencepacketstormsecurity.com/files/165214/Microsoft-Office-Word-MSHTML-Remote-Code-Execution.htmlunverifiedcve_referencepacketstormsecurity.com/files/164210/Microsoft-Windows-MSHTML-Overview.htmlunverified⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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http://packetstormsecurity.com/files/164210/Microsoft-Windows-MSHTML-Overview.htmlhttp://packetstormsecurity.com/files/165214/Microsoft-Office-Word-MSHTML-Remote-Code-Execution.htmlhttp://packetstormsecurity.com/files/167317/Microsoft-Office-MSDT-Follina-Proof-Of-Concept.htmlhttps://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40444https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40444