Known Exploited Vulnerability
7.1
HIGH
CVE-2021-43890
Microsoft Windows AppX Installer Spoofing Vulnerab - [Actively Exploited]
Description

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. 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. Please see the Security Updates table for the link to the updated app. Alternatively you can download and install the Installer using the links provided in the FAQ section. Please see the Mitigations and Workaround sections for important information about steps you can take to protect your system from this vulnerability. December 27 2023 Update: 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 ms-appinstaller URI scheme. 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.

INFO

Published Date :

Dec. 15, 2021, 3:15 p.m.

Last Modified :

July 24, 2024, 4:52 p.m.

Remotely Exploitable :

Yes !

Impact Score :

5.9

Exploitability Score :

1.2
CISA Notification
CISA KEV (Known Exploited Vulnerabilities)

For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.

Description :

Microsoft Windows AppX Installer contains a spoofing vulnerability which has a high impacts to confidentiality, integrity, and availability.

Required Action :

Apply updates per vendor instructions.

Public PoC/Exploit Available at Github

CVE-2021-43890 has a 1 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

Affected Products

The following products are affected by CVE-2021-43890 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Microsoft windows_10
2 Microsoft windows_10_1809
3 Microsoft windows_10_20h2
4 Microsoft windows_10_21h2
5 Microsoft windows_11_21h2
6 Microsoft windows_10_1507
7 Microsoft windows_10_1709
8 Microsoft windows_10_1803
9 Microsoft windows_10_21h1
10 Microsoft windows_10_1909
11 Microsoft app_installer
12 Microsoft windows_10_2004
13 Microsoft windows_10_1903
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2021-43890.

URL Resource
https://github.com/ChrisTitusTech/winutil/pull/26 Issue Tracking
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 Press/Media Coverage Third Party Advisory
https://www.bleepingcomputer.com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/ Press/Media Coverage Third Party Advisory
https://www.microsoft.com/en-us/security/blog/2023/12/28/financially-motivated-threat-actors-misusing-app-installer/ Exploit Vendor Advisory

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Ostorlab KEV: One-command to detect most remotely known exploitable vulnerabilities. Sourced from CISA KEV, Google's Tsunami, Ostorlab's Asteroid and Bug Bounty programs.

cisa-kev vulnerability 0day cisa exploits

Updated: 1 month, 4 weeks ago
516 stars 32 fork 32 watcher
Born at : April 19, 2022, 8:58 a.m. This repo has been linked 1181 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-43890 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2021-43890 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Modified Analysis by [email protected]

    Jul. 24, 2024

    Action Type Old Value New Value
    Changed Reference Type https://github.com/ChrisTitusTech/winutil/pull/26 No Types Assigned https://github.com/ChrisTitusTech/winutil/pull/26 Issue Tracking
    Changed Reference Type https://thehackernews.com/2023/12/microsoft-disables-msix-app-installer.html No Types Assigned https://thehackernews.com/2023/12/microsoft-disables-msix-app-installer.html Press/Media Coverage, Third Party Advisory
    Changed Reference Type https://www.bleepingcomputer.com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/ No Types Assigned https://www.bleepingcomputer.com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/ Press/Media Coverage, Third Party Advisory
    Changed Reference Type https://www.microsoft.com/en-us/security/blog/2023/12/28/financially-motivated-threat-actors-misusing-app-installer/ No Types Assigned https://www.microsoft.com/en-us/security/blog/2023/12/28/financially-motivated-threat-actors-misusing-app-installer/ Exploit, Vendor Advisory
    Changed CPE Configuration AND OR cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:x64:* cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:x86:* OR *cpe:2.3:a:microsoft:app_installer:*:*:*:*:*:*:*:* AND OR *cpe:2.3:a:microsoft:app_installer:*:*:*:*:*:*:*:* versions up to (excluding) 1.16 OR cpe:2.3:o:microsoft:windows_10_1809:-:*:*:*:*:*:*:* cpe:2.3:o:microsoft:windows_10_1903:-:*:*:*:*:*:*:* cpe:2.3:o:microsoft:windows_10_1909:-:*:*:*:*:*:*:* cpe:2.3:o:microsoft:windows_10_2004:-:*:*:*:*:*:*:* cpe:2.3:o:microsoft:windows_10_20h2:-:*:*:*:*:*:*:* cpe:2.3:o:microsoft:windows_10_21h1:-:*:*:*:*:*:*:* cpe:2.3:o:microsoft:windows_10_21h2:-:*:*:*:*:*:*:* cpe:2.3:o:microsoft:windows_11_21h2:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:a:microsoft:app_installer:*:*:*:*:*:*:*:* versions up to (excluding) 1.11 OR cpe:2.3:o:microsoft:windows_10_1507:-:*:*:*:*:*:*:* cpe:2.3:o:microsoft:windows_10_1709:-:*:*:*:*:*:*:* cpe:2.3:o:microsoft:windows_10_1803:-:*:*:*:*:*:*:*
  • CVE Modified by [email protected]

    May. 29, 2024

    Action Type Old Value New Value
    Changed 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> 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. 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. Please see the Security Updates table for the link to the updated app. Alternatively you can download and install the Installer using the links provided in the FAQ section. Please see the Mitigations and Workaround sections for important information about steps you can take to protect your system from this vulnerability. December 27 2023 Update: 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 ms-appinstaller URI scheme. 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.
  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • CVE Modified by [email protected]

    Dec. 30, 2023

    Action Type Old Value New Value
    Added Reference Microsoft Corporation https://www.bleepingcomputer.com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/ [No types assigned]
    Added Reference Microsoft Corporation https://thehackernews.com/2023/12/microsoft-disables-msix-app-installer.html [No types assigned]
    Added Reference Microsoft Corporation https://www.microsoft.com/en-us/security/blog/2023/12/28/financially-motivated-threat-actors-misusing-app-installer/ [No types assigned]
    Added Reference Microsoft Corporation https://github.com/ChrisTitusTech/winutil/pull/26 [No types assigned]
  • CVE Modified by [email protected]

    Dec. 28, 2023

    Action Type Old Value New Value
    Changed Description Windows AppX Installer Spoofing Vulnerability <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>
  • CWE Remap by [email protected]

    Jul. 12, 2022

    Action Type Old Value New Value
    Changed CWE CWE-290 NVD-CWE-noinfo
  • Modified Analysis by [email protected]

    Jan. 01, 2022

    Action Type Old Value New Value
  • CVE Modified by [email protected]

    Dec. 29, 2021

    Action Type Old Value New Value
    Added CVSS V3.1 Microsoft Corporation AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
  • Initial Analysis by [email protected]

    Dec. 23, 2021

    Action Type Old Value New Value
    Added CVSS V2 Metadata Victim must voluntarily interact with attack mechanism
    Added CVSS V2 NIST (AV:N/AC:M/Au:S/C:P/I:P/A:P)
    Added CVSS V3.1 NIST AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
    Changed Reference Type https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43890 No Types Assigned https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43890 Patch, Vendor Advisory
    Added CWE NIST CWE-290
    Added CPE Configuration AND OR *cpe:2.3:a:microsoft:app_installer:*:*:*:*:*:*:*:* OR cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:x64:* cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:x86:*
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-43890 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-43890 weaknesses.

Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

13.15 }} 0.04%

score

0.95637

percentile

CVSS31 - Vulnerability Scoring System
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability