Microsoft App Installer privilege escalation

Summaryinfo

A vulnerability was found in Microsoft App Installer. It has been declared as critical. Affected is an unknown function. Such manipulation leads to an unknown weakness. This vulnerability is traded as CVE-2021-43890. The attack may be launched remotely. Furthermore, there is an exploit available. Applying a patch is advised to resolve this issue.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Microsoft App Installer (version now known). Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The weakness was shared 12/14/2021 as confirmed security guidance (Website). The advisory is shared for download at portal.msrc.microsoft.com. This vulnerability is handled as CVE-2021-43890. Successful exploitation requires user interaction by the victim. Technical details are unknown but an exploit is available.

It is declared as attacked. This issue was added on 12/15/2021 to the CISA Known Exploited Vulnerabilities Catalog with a due date of 12/29/2021:

Apply updates per vendor instructions.

Applying a patch is able to eliminate this problem. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Zero-Day.cz (680). VulDB is the best source for vulnerability data and more expert information about this specific topic.

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Vendor

• Microsoft

Name

• App Installer

License

• commercial

Website

• Vendor: https://www.microsoft.com/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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