QID 91797

Date Published: 2021-07-22

QID 91797: Microsoft Windows Elevation of Privilege Vulnerability (CVE-2021-36934)(Zero-day)(HiveNightmare/SeriousSAM)

An elevation of privilege vulnerability exists because of overly permissive Access Control Lists (ACLs) on multiple system files, including the Security Accounts Manager (SAM) database. An attacker who successfully exploits this vulnerability can run arbitrary code with SYSTEM privileges. An attacker can then install programs; view, change, or delete data; or create new accounts with full user rights.

An attacker must have the ability to execute code on a victim system to exploit this vulnerability.

Affected Versions:
Windows 10 version 1809 and Later
Windows Server 2019 and later server versions (except Windows Server, version 20H2)

QID Detection Logic: (authenticated)
The QID checks the OS is Windows 10 version 1809, Windows Server 2019 or later (except Windows Server, version 20H2).

An attacker who successfully exploits this vulnerability can run arbitrary code with SYSTEM privileges.

  • CVSS V3 rated as High - 7.8 severity.
  • CVSS V2 rated as Medium - 4.6 severity.
  • Solution
    Currently there are no patches for this vulnerability.

    Workaround:
    Restrict access to the contents of %windir%\system32\config

    Open Command Prompt or Windows PowerShell as an administrator.

    Run this command: icacls %windir%\system32\config\*.* /inheritance:e

    Delete Volume Shadow Copy Service (VSS) shadow copies

    Delete any System Restore points and Shadow volumes that existed prior to restricting access to %windir%\system32\config.

    Create a new System Restore point (if desired).

    Impact of workaround Deleting shadow copies could impact restore operations, including the ability to restore data with third-party backup applications.

    Note: You must restrict access and delete shadow copies to prevent exploitation of this vulnerability.

    CVEs related to QID 91797

    Software Advisories
    Advisory ID Software Component Link

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