8.8 CVE-2021-34527

<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_MACHINESOFTWAREPoliciesMicrosoftWindows NTPrintersPointAndPrint</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>
https://nvd.nist.gov/vuln/detail/CVE-2021-34527

Categories

CWE-269 : Improper Privilege Management
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.) Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software. Follow the principle of least privilege when assigning access rights to entities in a software system. Consider following the principle of separation of privilege. Require multiple conditions to be met before permitting access to a system resource. Terminal privileges are not reset when a user logs out. Does not properly pass security context to child processes in certain cases, allows privilege escalation. Does not properly compute roles. untrusted user placed in unix "wheel" group Product allows users to grant themselves certain rights that can be used to escalate privileges. Product uses group ID of a user instead of the group, causing it to run with different privileges. This is resultant from some other unknown issue. Product mistakenly assigns a particular status to an entity, leading to increased privileges. FTP client program on a certain OS runs with setuid privileges and has a buffer overflow. Most clients do not need extra privileges, so an overflow is not a vulnerability for those clients. OS incorrectly installs a program with setuid privileges, allowing users to gain privileges. Composite: application running with high privileges (CWE-250) allows user to specify a restricted file to process, which generates a parsing error that leaks the contents of the file (CWE-209). Installation script installs some programs as setuid when they shouldn't be. Roles have access to dangerous procedures (Accessible entities). Untrusted object/method gets access to clipboard (Accessible entities). Traceroute program allows unprivileged users to modify source address of packet (Accessible entities). User with capability can prevent setuid program from dropping privileges (Unsafe privileged actions).

References

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REMEDIATION

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EXPLOITS

Exploit-db.com

POC Github

Other Nist (github, ...)

CAPEC

Common Attack Pattern Enumerations and Classifications

MITRE

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