Advisory Details

March 15th, 2021

Microsoft Windows win32kfull bStretch NULL Pointer Dereference Privilege Escalation Vulnerability

ZDI-21-287
ZDI-CAN-12672

CVE ID CVE-2021-27077
CVSS SCORE 7.8, (AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H)
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Windows
VULNERABILITY DETAILS

This vulnerability allows local attackers to escalate privileges on affected installations of Microsoft Windows. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the win32kfull.sys driver. The issue results from dereferencing a NULL pointer. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of SYSTEM.

ADDITIONAL DETAILS Microsoft has issued an update to correct this vulnerability. More details can be found at:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-27077
DISCLOSURE TIMELINE
  • 2020-12-23 - Vulnerability reported to vendor
  • 2021-03-15 - Coordinated public release of advisory
CREDIT Marcin Wiazowski
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