Attacker Value
Moderate
(4 users assessed)
Exploitability
Low
(4 users assessed)
User Interaction
Required
Privileges Required
None
Attack Vector
Network
10

CVE-2021-40444

Disclosure Date: September 15, 2021
Exploited in the Wild
Add MITRE ATT&CK tactics and techniques that apply to this CVE.
Execution
Techniques
Validation
Validated
Validated
Validated

Description

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.

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.

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”.

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.

Please see the Mitigations and Workaround sections for important information about steps you can take to protect your system from this vulnerability.

UPDATE 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.

Add Assessment

3
Ratings
Technical Analysis
  • Vulnerable if default behaviour has been changed ( By default, Microsoft Office opens documents from the internet in Protected View or Application Guard for Office both of which prevent the current attack )
  • Requires social engineering to be exploited
  • Workaround easy to deploy
2
Ratings
Technical Analysis

CVE-2021-40444

Vulnerability:

  • Microsoft MSHTML Remote Code Execution Vulnerability
  • Tested with malicious .exe file

Executive Summary:

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.

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.

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”.

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.

Please see the Mitigations and Workaround sections for important information about steps you can take to protect your system from this vulnerability.

UPDATE 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.


Conclusion:

  • Security is not checked
  • Just OPEN :D

Risk Assessment:

  • This may well be a meterpreter malicious backdoor shell file
  • This may well be a malicious MSI package or hidden bat file

Status:

  • Low(Medium)

Fixed

  • Windows 11

Source:

href

Reproduce:

href

Demo docx:

href

Demo VLC:

href

CVSS V3 Severity and Metrics
Base Score:
8.8 High
Impact Score:
5.3
Exploitability Score:
2.8
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L
Attack Vector (AV):
Network
Attack Complexity (AC):
Low
Privileges Required (PR):
None
User Interaction (UI):
Required
Scope (S):
Changed
Confidentiality (C):
Low
Integrity (I):
High
Availability (A):
Low

General Information

Vendors

  • microsoft

Products

  • windows 10 -,
  • windows 10 1607,
  • windows 10 1809,
  • windows 10 1909,
  • windows 10 2004,
  • windows 10 20h2,
  • windows 10 21h1,
  • windows 7 -,
  • windows 8.1 -,
  • windows rt 8.1 -,
  • windows server 2008 -,
  • windows server 2008 r2,
  • windows server 2012 -,
  • windows server 2016 -,
  • windows server 2016 2004,
  • windows server 2016 20h2,
  • windows server 2019 -,
  • windows server 2022 -

Exploited in the Wild

Reported by:
Technical Analysis