Vulnerability Details : CVE-2021-34527

Public exploit exists!
Used for ransomware!
<p>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.</p> <p>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.</p> <p>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 (<strong>Note</strong>: 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):</p> <ul> <li>HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Printers\PointAndPrint</li> <li>NoWarningNoElevationOnInstall = 0 (DWORD) or not defined (default setting)</li> <li>UpdatePromptSettings = 0 (DWORD) or not defined (default setting)</li> </ul> <p><strong>Having NoWarningNoElevationOnInstall set to 1 makes your system vulnerable by design.</strong></p> <p>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 <a href="https://support.microsoft.com/topic/31b91c02-05bc-4ada-a7ea-183b129578a7">KB5005010: Restricting installation of new printer drivers after applying the July 6, 2021 updates</a>.</p> <p>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.</p>
Published 2021-07-02 22:15:09
Updated 2025-03-13 16:41:56
Source Microsoft Corporation
View at NVD,   CVE.org
Vulnerability category: Execute code

Products affected by CVE-2021-34527

CVE-2021-34527 is in the CISA Known Exploited Vulnerabilities Catalog

This issue is known to have been leveraged as part of a ransomware campaign.
CISA vulnerability name:
Microsoft Windows Print Spooler Remote Code Execution Vulnerability
CISA required action:
Apply updates per vendor instructions.
CISA description:
Microsoft Windows Print Spooler contains an unspecified vulnerability due to the Windows Print Spooler service improperly performing privileged file operations. Successful exploitation allows an attacker to perform remote code execution with SYSTEM privileges. The vulnerability is also known under t
Notes:
Reference CISA's ED 21-04 (https://www.cisa.gov/news-events/directives/ed-21-04-mitigate-windows-print-spooler-service-vulnerability) for further guidance and requirements. Note: The due date for addressing this vulnerability aligns with the requirements outlined in ED 21-04. https://nvd.nist.gov/vu
Added on 2021-11-03 Action due date 2021-07-20

Exploit prediction scoring system (EPSS) score for CVE-2021-34527

EPSS FAQ
94.26%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 100 %
Percentile, the proportion of vulnerabilities that are scored at or less

Metasploit modules for CVE-2021-34527

  • Print Spooler Remote DLL Injection
    Disclosure Date: 2021-06-08
    First seen: 2022-12-23
    exploit/windows/dcerpc/cve_2021_1675_printnightmare
    The print spooler service can be abused by an authenticated remote attacker to load a DLL through a crafted DCERPC request, resulting in remote code execution as NT AUTHORITY\SYSTEM. This module uses the MS-RPRN vector which requires the Print Spooler service to be run
  • Print Spooler Remote DLL Injection
    First seen: 2021-07-07
    auxiliary/admin/dcerpc/cve_2021_1675_printnightmare
    auxiliary/admin/dcerpc/cve_2021_1675_printnightmare The print spooler service can be abused by an authenticated remote attacker to load a DLL through a crafted DCERPC request, resulting in remote code execution as NT AUTHORITY\SYSTEM. This module uses the MS-RPRN vecto

CVSS scores for CVE-2021-34527

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
9.0
 HIGH AV:N/AC:L/Au:S/C:C/I:C/A:C
8.0
10.0
 NIST
8.8
 HIGH CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
2.8
5.9
 NIST
8.8
 HIGH CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
2.8
5.9
 Microsoft Corporation

References for CVE-2021-34527

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