CVE coverage

CVE-2021-34527

CVSS 8.8 Actively exploited (KEV) 19 detections found

A remote code execution vulnerability exists when the Windows Print Spooler service improperly performs privileged file operations. An attacker who successfully exploited this vulnerability could run arbitrary code with SYSTEM privileges. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. UPDATE July 7, 2021: The security update for Windows Server 2012, Windows Server 2016 and Windows 10, Version 1607 have been released. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability. In addition to installing the updates, in order to secure your system, you must confirm that the following registry settings are set to 0 (zero) or are not defined (Note: These registry keys do not exist by default, and therefore are already at the secure setting.), also that your Group Policy setting are correct (see FAQ): HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint NoWarningNoElevationOnInstall = 0 (DWORD) or not defined (default setting) UpdatePromptSettings = 0 (DWORD) or not defined (default setting) Having NoWarningNoElevationOnInstall set to 1 makes your system vulnerable by design. UPDATE July 6, 2021: Microsoft has completed the investigation and has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. If you are unable to install these updates, see the FAQ and Workaround sections in this CVE for information on how to help protect your system from this vulnerability. See also KB5005010: Restricting installation of new printer drivers after applying the July 6, 2021 updates. Note that the security updates released on and after July 6, 2021 contain protections for CVE-2021-1675 and the additional remote code execution exploit in the Windows Print Spooler service known as “PrintNightmare”, documented in CVE-2021-34527.

Detection rules

Source	Rule	Status	Updated
elastic	Suspicious Print Spooler File Deletion	production	2026-09-18
elastic	Unusual Print Spooler Child Process	production	2026-09-18
splunk	Print Spooler Failed to Load a Plug-in	production	2026-05-13
splunk	Print Spooler Adding A Printer Driver	production	2026-05-13
splunk	Rundll32 with no Command Line Arguments with Network	production	2026-05-13
splunk	Spoolsv Spawning Rundll32	production	2026-05-13
splunk	Spoolsv Suspicious Loaded Modules	production	2026-05-13
splunk	Spoolsv Suspicious Process Access	production	2026-05-13
splunk	Spoolsv Writing a DLL	production	2026-05-13
splunk	Spoolsv Writing a DLL - Sysmon	production	2026-05-13
splunk	Suspicious Rundll32 no Command Line Arguments	production	2026-05-13
sigma	Possible PrintNightmare Print Driver Install - CVE-2021-1675	stable	2025-11-03
sigma	Antivirus PrinterNightmare CVE-2021-34527 Exploit Detection	stable	2023-10-23
sigma	PrinterNightmare Mimikatz Driver Name	test	2023-06-12
sigma	CVE-2021-1675 Print Spooler Exploitation IPC Access	test	2022-10-05
sigma	Windows Spooler Service Suspicious Binary Load	test	2022-06-02
elastic	Potential PrintNightmare File Modification	deprecated	2022-03-16
elastic	Potential PrintNightmare Exploit Registry Modification	deprecated	2022-03-16
sigma	Remote Printing Abuse for Lateral Movement	test	2022-01-01