Advisory Details

November 11th, 2021

Microsoft Windows Installer Service Link Following Privilege Escalation Vulnerability

ZDI-21-1308
ZDI-CAN-14616

CVE ID CVE-2021-41379
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 Windows Installer service. By creating a junction, an attacker can abuse the service to delete a file or directory. 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-2021-41379
DISCLOSURE TIMELINE
  • 2021-08-10 - Vulnerability reported to vendor
  • 2021-11-11 - Coordinated public release of advisory
CREDIT Abdelhamid Naceri
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