Advisory Details

January 14th, 2021

Microsoft Windows Print Spooler Directory Junction Privilege Escalation Vulnerability

ZDI-21-019
ZDI-CAN-11909

CVE ID CVE-2021-1695
CVSS SCORE 7.8, AV:L/AC:L/PR:L/UI:N/S:U/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 Print Spooler service. By creating a directory junction, an attacker can abuse the Print Spooler service to create a file in an arbitrary location. An attacker can leverage this vulnerability to escalate privileges and execute 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-2021-1695
DISCLOSURE TIMELINE
  • 2020-09-25 - Vulnerability reported to vendor
  • 2021-01-14 - Coordinated public release of advisory
CREDIT JeongOh Kyea (@kkokkokye) of THEORI
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