Summary
Impact: Remote Code Execution. Microsoft rating: Critical. Exploited according to Microsoft, publicly disclosed before the fix — Exploitation Detected. Customer action: Required.
Details
If I have not yet installed the security update released Out-of-Band on July 6 and 7, 2021, then do I need to install both the Out-of-Band security update released on July 6 and 7, 2021, and the monthly security updates released on July 13, 2021 to be protected from PrintNightmare?
All monthly security updates are cumulative, including the monthly security updates released on July 13, 2021. The July 13, 2021 cumulative security updates contain all previous security fixes - including the security fix for the print spooler vulnerability (CVE-2021-34527). Customers who have not previously deployed the OOB fix released on July 6 and 7, 2021, can skip deploying the OOB update and deploy the July cumulative security updates released on July 13, 2021, to be protected.
Yes, Microsoft has assigned CVE-2021-34527 to this vulnerability.
This vulnerability is similar but distinct from the vulnerability that is assigned CVE-2021-1675. The attack vector is different as well. CVE-2021-1675 was addressed by the security update released on June 8, 2021.
No, the vulnerability existed before the June 8, 2021 security update.
All versions of Windows are vulnerable. As of July 7, 2021, Microsoft has released security updates for this vulnerability for all supported versions of Windows listed in the security updates table in this CVE.
The security updates released on and after July 6, 2021 contain protections for a remote code execution exploit in the Windows Print Spooler service known as “PrintNightmare”, documented in CVE-2021-34527, as well as for CVE-2021-1675.
Domain controllers are affected if the print spooler service is enabled.
Yes. All editions of Windows are affected.
Security products, like Microsoft 365 Defender, offer different ways to view relevant alerts and telemetry. Microsoft has published our recommendations for seeing this sort of behavior at our GitHub here: Microsoft 365 Defender Hunting Queries. Customers using other technologies can adapt this logic for use in their environments.
Point and Print is not directly related to this vulnerability, but certain configurations make systems vulnerable to exploitation.
Please see KB5005010: Restricting installation of new printer drivers after applying the July 6, 2021 updates for complete information.
Please see KB5005010: Restricting installation of new printer drivers after applying the July 6, 2021 updates for complete information.
Security updates
10.0.17763.2029 — https://support.microsoft.com/help/5004947
10.0.20348.230 — https://support.microsoft.com/help/5005575
10.0.19042.1083 — https://support.microsoft.com/help/5004945
10.0.22000.318 — https://support.microsoft.com/help/5007215
10.0.19044.1415 — https://support.microsoft.com/help/5008212
10.0.22621.674 — https://support.microsoft.com/help/5018427
10.0.19045.2251 — https://support.microsoft.com/help/5019959
10.0.10240.18969 — https://support.microsoft.com/help/5004950
10.0.14393.4470 — https://support.microsoft.com/help/5004948
6.3.9600.20046 — https://support.microsoft.com/help/5004954
6.0.6003.21138 — https://support.microsoft.com/help/5004955
6.0.6003.21138 — https://support.microsoft.com/help/5004959
6.1.7601.25633 — https://support.microsoft.com/help/5004953
6.1.7601.25633 — https://support.microsoft.com/help/5004951
6.2.9200.23383 — https://support.microsoft.com/help/5004956
6.2.9200.23383 — https://support.microsoft.com/help/5004960
6.3.9600.20046 — https://support.microsoft.com/help/5004958
Vulnerabilities 1
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High 8.8
Windows Print Spooler Remote Code Execution Vulnerability
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 th…
KEV Nov 3, 2021
Revision history
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#11
In the Security Updates table, added all supported editions of Windows 10 version 21H2, Windows 11 version 21H2, Windows 11 version 22H2, and Windows Server 2022 as they are affected by this vulnerability. Customers running any of these versions of Windows should install listed updates or newer to be protected from this vulnerability. After these updates are installed, please follow the advice included in the documentation on this CVE. With this revision, products that are no longer in support have been removed.
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#10
Added an acknowledgement. This is an informational change only.
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#9
Added FAQ information. This is an informational change only.
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#8
Added information to the executive summary and the FAQ sections. This is an informational change only.
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#7
CVE updated to announce that Microsoft is releasing an update for Windows 10 version 1607, Windows Server 2016, and Windows Server 2012. Other information has been updated as well.
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#6
CVE updated to announce that Microsoft is releasing an update for several versions of Window to address this vulnerability. Updates are not yet available for Windows 10 version 1607, Windows Server 2016, or Windows Server 2012. Security updates for these versions of Windows will be released soon. Other information has been updated as well. This information will be updated when more information or updates are available.
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#5
Updated FAQ information. This is an informational change only.
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#2
Updated FAQ information. This is an informational change only.
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#3
The information in the workaround section was updated. This an informational change only.
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#4
CVE revised to update the FAQ, add a mitigation, and add the CVSS score. These are informational changes only.
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#1
Information published.
References
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CVE-2021-34527 Windows Print Spooler Remote Code Execution Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34527
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss