Advisory Details

July 19th, 2021

Microsoft Windows InstallService Time-Of-Check Time-Of-Use Denial-of-Service Vulnerability

ZDI-21-818
ZDI-CAN-12925

CVE ID CVE-2021-31961
CVSS SCORE 6.1, (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H)
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Windows
VULNERABILITY DETAILS

This vulnerability allows local attackers to create a denial-of-service condition 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 Microsoft Store Install Service. The issue results from the lack of proper locking when performing operations on a file. An attacker can leverage this vulnerability to create a denial-of-service condition on the 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-2021-31961
DISCLOSURE TIMELINE
  • 2021-02-08 - Vulnerability reported to vendor
  • 2021-07-19 - Coordinated public release of advisory
CREDIT JeongOh Kyea (@kkokkokye) of THEORI
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