SB2021121475 - Privilege escalation in Microsoft Windows Setup

Description

This security bulletin contains information about 1 vulnerability.

1) Link following (CVE-ID: CVE-2021-43237)

CWE-ID: CWE-59 - Improper Link Resolution Before File Access ('Link Following')

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:U/U:Clear

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

The vulnerability exists due to insecure link following in Windows Setup. A local user can create a symbolic link to arbitrary file on the system and overwrite it.

Successful exploitation of the vulnerability allows privilege escalation but requires that an administrator must begin a version update of Windows.

Remediation

Install update from vendor's website.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43237
• https://www.zerodayinitiative.com/advisories/ZDI-22-018/