HTTP Protocol Stack Remote Code Execution Vulnerability
Actively exploited in the wild. Patch or mitigate immediately — don't wait for a maintenance window.
An unauthenticated attacker, remotely over the network, with no user interaction, can fully compromise the system — steal data, tamper with it and take it offline.
HTTP Protocol Stack Remote Code Execution Vulnerability
Techniques marked “observed” are corroborated by threat intelligence; the rest are inferred from the weakness type (CWE) and attack vector.
Corroborated threat activity referencing this CVE — with source and confidence, not inference.
These techniques were analysed against this CVE's real-world exploitation — the matching entries in the ATT&CK chain above are marked “observed”.
Generated by Wavense from the CVE record — an immediate mitigation and the permanent fix.
To temporarily reduce risk, block untrusted HTTP/HTTPS traffic at the network perimeter using a firewall. If possible, restrict access to affected web servers from external networks to only trusted IP ranges or VPN connections. Implement robust intrusion detection systems (IDS) and endpoint detection and response (EDR) to monitor for suspicious activity and potential exploitation attempts.
The permanent resolution is to apply the security updates released by Microsoft for the affected HTTP Protocol Stack (HTTP.sys). Specifically, ensure that all Windows 10 versions 2004, 20H2, and Windows Server 2019 systems are updated with the patches addressing CVE-2021-31166. This update resolves the use-after-free vulnerability, preventing remote code execution.
Exploitation of this vulnerability allows an unauthenticated, remote attacker to execute arbitrary code with kernel-level privileges on the target system. This can lead to a complete system compromise, enabling attackers to install programs, view, change, or delete data, or create new accounts with full user rights. The business consequences include severe data breaches, service disruption, and potential regulatory fines.
Other CVEs affecting windows 10 2004
Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability
Windows Scripting Languages Remote Code Execution Vulnerability
Active Directory Domain Services Elevation of Privilege Vulnerability
Microsoft is investigating reports of a remote code execution vulnerability in MSHTML that affects Microsoft Windows. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability by using specially-crafted Microsoft Office documents. An attacker could craft a malicious ActiveX control to be used by a Microsoft Office document that hosts the browser rendering engine. The attacker would then have to convince the user to open the malicious document. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. Microsoft Defender Antivirus and Microsoft Defender for Endpoint both provide detection and protections for the known vulnerability. Customers should keep antimalware products up to date. Customers who utilize automatic updates do not need to take additional action. Enterprise customers who manage updates should select the detection build 1.349.22.0 or newer and deploy it across their environments. Microsoft Defender for Endpoint alerts will be displayed as: “Suspicious Cpl File Execution”. Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs. Please see the Mitigations and Workaround sections for important information about steps you can take to protect your system from this vulnerability. UPDATE September 14, 2021: Microsoft 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. Please see the FAQ for important information about which updates are applicable to your system.
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.