Microsoft Windows Print Spooler Remote Code Execution Vulnerability

Exploited · KEV 2021-11-03RansomwareMetasploit moduleCVE-2021-34527CWE-269

Exploited since 2021-11-03. No WAF vendor names it yet.

Edge rules

0/8

Our test

No exploit yet

CVSS

8.8

EPSS

99.8% Top 0.1%

Posts, 14d

Published

2021-07-02

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.

Edge coverage

Claimed by vendors

CloudflareBefore feed historyOlder than its feed AWSNo public claimNot named Microsoft AzureNo public claimNot named Google CloudBefore feed historyOlder than its feed FastlyBefore feed historyOlder than its feed F5Before feed historyOlder than its feed AkamaiNo public sourceNo public changelog OWASP CRSBefore feed historyOlder than its feed

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Severity, decoded

CVSS 3.1

8.8High

High · 8.8 / 10

Exploitable over the network, with low privileges and no user interaction, leading to full loss of confidentiality, integrity and availability.

Over the internetAny user loginNo user actionWorks reliablyFull compromise

How the score is built8 metrics

Attack vectorAn attacker can reach it over the internet; no access to your network needed.
Network
Attack complexityNo special conditions are needed; the attack works reliably.
Low
Privileges requiredThe attacker needs an ordinary user account.
Low
User interactionNo one has to click or open anything; the attack works on its own.
None
ScopeThe damage stays within the vulnerable component.
Unchanged
Confidentiality impactAn attacker can read all data the affected component holds, or the most sensitive parts of it.
High
Integrity impactAn attacker can change any data or files the affected component protects.
High
Availability impactAn attacker can take the component down completely or keep it from serving anyone.
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C

Also in the vector: Exploit code maturity: Functional · Remediation level: Official fix · Report confidence: Confirmed

CISA's assessmentSSVC, from the CVE record

ExploitationActive

Attackers are exploiting this in the wild.

AutomatableNo

At least one step needs hands-on work, which slows mass attacks.

Technical impactTotal

A successful attack gives full control over the affected software or all of its data.

Public exploits

1 found

1 Metasploit0 Exploit-DB0 Scanner template0 GitHub PoCs

MetasploitPrint Spooler Remote DLL Injection2021-06-08 · exploit · rank Normal · has check

Links are to third-party code: never run it outside an isolated lab.

Timeline

2021-06-08
Metasploit module published
Print Spooler Remote DLL Injection
2021-07-02
CVE published
CVE List
2021-11-03
Added to CISA KEV
Confirmed exploitation in the wild