SB2021112505 - Privilege escalation in Microsoft Windows

Description

This security bulletin contains information about 1 vulnerability.

1) Permissions, Privileges, and Access Controls (CVE-ID: CVE-2021-43890)

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Amber

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to incorrect permissions in windows installer service. A local user can run a specially crafted program to execute arbitrary code with SYSTEM privileges.

The vulnerability exists due to incomplete patch for #VU58061 (CVE-2021-41379).

Note, the vulnerability is being actively exploited in the wild.

Remediation

Install update from vendor's website.

References

• https://github.com/klinix5/InstallerFileTakeOver
• https://blog.talosintelligence.com/2021/11/attackers-exploiting-zero-day.html
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43890