^{CVE-2021-34498:}Windows GDI Elevation of Privilege Vulnerability (CVE-2021-34498)

Overview

This vulnerability exists in the Windows Graphics Device Interface (GDI), which is a core component of the Windows operating system responsible for representing graphical objects and transmitting them to output devices. The issue stems from a use-after-free flaw (CWE-416) where the system incorrectly handles objects in memory, allowing an attacker to potentially manipulate freed memory to execute code with elevated privileges. To exploit this vulnerability, an attacker would need to run a specially crafted application on a vulnerable system. If successful, the attacker could gain SYSTEM-level privileges, effectively taking complete control of the affected system. This vulnerability affects multiple versions of Windows operating systems and requires local access to exploit.

Remediation

To address this vulnerability, users and administrators should:

1. Apply the security updates provided by Microsoft as part of their July 2021 Patch Tuesday release.
2. Ensure automatic updates are enabled on all Windows systems.
3. If patching is not immediately possible, consider implementing the following mitigations:
   • Restrict access to local systems to trusted users only
   • Implement the principle of least privilege for all user accounts
   • Monitor systems for suspicious activities that might indicate exploitation attempts
4. After applying patches, restart affected systems to ensure the updates take effect.
5. Keep all Windows systems updated with the latest security patches as they become available.

References

1. Microsoft Security Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34498
2. Zero Day Initiative Advisory: https://www.zerodayinitiative.com/advisories/ZDI-21-825/
3. Common Weakness Enumeration: CWE-416 (Use After Free) - https://cwe.mitre.org/data/definitions/416.html
4. Microsoft Windows GDI Documentation: https://docs.microsoft.com/en-us/windows/win32/gdi/windows-gdi