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CVE-2021-43890 Detail

Current Description

<p>We have investigated reports of a spoofing vulnerability in AppX installer that affects Microsoft Windows. Microsoft is aware of attacks that attempt to exploit this vulnerability by using specially crafted packages that include the malware family known as Emotet/Trickbot/Bazaloader.</p> <p>An attacker could craft a malicious attachment to be used in phishing campaigns. The attacker would then have to convince the user to open the specially crafted attachment. 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>Please see the <strong>Security Updates</strong> table for the link to the updated app. Alternatively you can download and install the Installer using the links provided in the <strong>FAQ</strong> section.</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>December 27 2023 Update:</strong></p> <p>In recent months, Microsoft Threat Intelligence has seen an increase in activity from threat actors leveraging social engineering and phishing techniques to target Windows OS users and utilizing the <a href="https://learn.microsoft.com/en-us/windows/msix/app-installer/installing-windows10-apps-web">ms-appinstaller URI scheme</a>.</p> <p>To address this increase in activity, we have updated the App Installer to disable the ms-appinstaller protocol by default and recommend other potential mitigations.</p>


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score matches with CNA score
CNA:  Microsoft Corporation
Base Score:  7.1 HIGH
Vector:  CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H


NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: The NVD and the CNA have provided the same score. When this occurs only the CNA information is displayed, but the Acceptance Level icon for the CNA is given a checkmark to signify NVD concurrence.

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Hyperlink Resource
https://github.com/ChrisTitusTech/winutil/pull/26
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43890 Patch  Vendor Advisory 
https://thehackernews.com/2023/12/microsoft-disables-msix-app-installer.html
https://www.bleepingcomputer.com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/
https://www.microsoft.com/en-us/security/blog/2023/12/28/financially-motivated-threat-actors-misusing-app-installer/

This CVE is in CISA's Known Exploited Vulnerabilities Catalog

Reference CISA's BOD 22-01 and Known Exploited Vulnerabilities Catalog for further guidance and requirements.

Vulnerability Name Date Added Due Date Required Action
Microsoft Windows AppX Installer Spoofing Vulnerability 12/15/2021 12/29/2021 Apply updates per vendor instructions.

Weakness Enumeration

CWE-ID CWE Name Source
NVD-CWE-noinfo Insufficient Information cwe source acceptance level NIST  

Known Affected Software Configurations Switch to CPE 2.2

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Change History

6 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2021-43890
NVD Published Date:
12/15/2021
NVD Last Modified:
12/30/2023
Source:
Microsoft Corporation