Detections
Explore public detection logic contributed by the community across SIEM and rule languages.
21 detections
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Detects the Print Spooler service (spoolsv.exe) spawning a shell/script interpreter or rundll32.exe as a child process, or loading a DLL from a driver-store/temp/ProgramData path — the process-injection and arbitrary-DLL-load pattern characteristic of PrintNightmare (CVE-2021-34527) exploitation.
Detects the Print Spooler service (spoolsv.exe) spawning a shell/script interpreter or rundll32.exe as a child process, or loading a DLL from a driver-store/temp/ProgramData path — the process-injection and arbitrary-DLL-load pattern characteristic of PrintNightmare (CVE-2021-34527) exploitation.
Detects potential PrintNightmare or Print Spooler exploitation by monitoring for the spoolsv.exe service spawning suspicious child processes (e.g., cmd, powershell, rundll32) and unauthorized files being dropped into the printer driver directory.
Detects potential PrintNightmare or Print Spooler exploitation by monitoring for the spoolsv.exe service spawning suspicious child processes (e.g., cmd, powershell, rundll32) and unauthorized files being dropped into the printer driver directory.
Detects potential exploitation of CVE-2021-1675 / CVE-2021-34527 (PrintNightmare) via anomalous SMB access to the IPC$ share targeting the "spoolss" named pipe (AccessMask: 0x3).
This pattern is associated with RPC-based abuse of the Windows Print Spooler service, which may allow remote code execution or privilege escalation with SYSTEM privileges.
This pattern is associated with RPC-based abuse of the Windows Print Spooler service, which may allow remote code execution or privilege escalation with SYSTEM privileges.
Detects the creation of suspicious files associated with Proof-of-Concept (PoC) exploits targeting the Windows Print Spooler Remote Code Execution Vulnerabilities, specifically CVE-2021-34527 (PrinterNightmare) and CVE-2021-1675. The rule looks for file creations within the ':\Windows\System32\spool\drivers\x64\' directory, which is a known location for files dropped by these exploits.
The analytic detects the execution of rundll32.exe without any command line arguments. This behavior is identified using Endpoint Detection and Response (EDR) telemetry, focusing on process execution logs. It is significant because rundll32.exe typically requires command line arguments to function properly, and its absence is often associated with malicious activities, such as those performed by Cobalt Strike. If confirmed malicious, this activity could indicate an attempt to execute arbitrary code, potentially leading to credential dumping, unauthorized file writes, or other malicious actions.
This rule detects remote procedure call (RPC) activity related to the Print System Remote Protocol (MS-RPRN) and Print System Asynchronous Remote Protocol (MS-PAR) interfaces. Specifically, it looks for RPC Firewall events (EventLog: RPCFW, EventID: 3) where the InterfaceUuid matches known UUIDs associated with these printing protocols. This activity can indicate an attempt to abuse remote printing services for lateral movement within a network, potentially exploiting vulnerabilities like CVE-2021-34527 (PrintNightmare).
Detects remote RPC calls to possibly abuse remote printing service via MS-RPRN / MS-PAR
The analytic detects `spoolsv.exe` writing a `.dll` file, which is unusual behavior and may indicate exploitation of vulnerabilities like CVE-2021-34527 (PrintNightmare). This detection leverages the Endpoint datamodel, specifically monitoring process and filesystem events to identify `.dll` file creation within the `\spool\drivers\x64\` path. This activity is significant as it may signify an attacker attempting to execute malicious code via the Print Spooler service. If confirmed malicious, this could lead to unauthorized code execution and potential system compromise. Immediate endpoint isolation and further investigation are recommended.
The following analytic detects `spoolsv.exe` writing a `.dll` file, which is unusual behavior and may indicate exploitation of vulnerabilities like CVE-2021-34527 (PrintNightmare). This detection leverages Sysmon EventID 11 to monitor file creation events in the `\spool\drivers\x64\` directory. This activity is significant because `spoolsv.exe` typically does not write DLL files, and such behavior could signify an ongoing attack. If confirmed malicious, this could allow an attacker to execute arbitrary code, escalate privileges, or maintain persistence on the compromised system.
The analytic detects the addition of new printer drivers by monitoring Windows PrintService operational logs, specifically EventCode 316. This detection leverages log data to identify messages indicating the addition or update of printer drivers, such as "kernelbase.dll" and "UNIDRV.DLL." This activity is significant as it may indicate exploitation attempts related to vulnerabilities like CVE-2021-34527 (PrintNightmare). If confirmed malicious, attackers could gain code execution or escalate privileges, potentially compromising the affected system. Immediate isolation and investigation of the endpoint are recommended.
The analytic detects the suspicious loading of DLLs by spoolsv.exe, potentially indicating PrintNightmare exploitation. It leverages Sysmon EventCode 7 to identify instances where spoolsv.exe loads multiple DLLs from the Windows System32 spool drivers x64 directory. This activity is significant as it may signify an attacker exploiting the PrintNightmare vulnerability to execute arbitrary code. If confirmed malicious, this could lead to unauthorized code execution, privilege escalation, and persistent access within the environment, posing a severe security risk.
This analytic detects the execution of rundll32.exe without any command-line arguments, immediately followed by a network connection. This behavior is suspicious because rundll32.exe typically requires arguments to perform legitimate functions. Its use without arguments, especially when combined with network activity, is often indicative of malicious activity, such as the execution of Cobalt Strike beacons or other malware attempting to establish unauthorized network communications for data exfiltration or further system compromise. The detection relies on correlating endpoint process telemetry with network traffic data.
The following analytic detects suspicious process access by spoolsv.exe, potentially indicating exploitation of the PrintNightmare vulnerability (CVE-2021-34527). It leverages Sysmon EventCode 10 to identify when spoolsv.exe accesses critical system files or processes like rundll32.exe with elevated privileges. This activity is significant as it may signal an attempt to gain unauthorized privilege escalation on a vulnerable machine. If confirmed malicious, an attacker could achieve elevated privileges, leading to further system compromise, persistent access, or unauthorized control over the affected environment.
The analytic detects driver load errors in the Windows PrintService Admin logs, specifically identifying issues related to CVE-2021-34527 (PrintNightmare). It triggers on error messages indicating the print spooler failed to load a plug-in module, such as "meterpreter.dll," with error code 0x45A. This detection method leverages specific event codes and error messages. This activity is significant as it may indicate an exploitation attempt of a known vulnerability. If confirmed malicious, an attacker could gain unauthorized code execution on the affected system, leading to potential system compromise.
The following analytic detects the spawning of `rundll32.exe` without command-line arguments by `spoolsv.exe`, which is unusual and potentially indicative of exploitation attempts like CVE-2021-34527 (PrintNightmare). This detection leverages Endpoint Detection and Response (EDR) telemetry, focusing on process creation events where `spoolsv.exe` is the parent process. This activity is significant as `spoolsv.exe` typically does not spawn other processes, and such behavior could indicate an active exploitation attempt. If confirmed malicious, this could allow an attacker to execute arbitrary code, escalate privileges, or maintain persistence on the compromised endpoint.
Detects suspicious DLL loads by the Windows Print Spooler service from its backup driver folders. This behavior is indicative of exploitation attempts related to vulnerabilities like PrintNightmare (CVE-2021-1675, CVE-2021-34527) where an attacker can force the spooler service to load arbitrary DLLs, leading to privilege escalation or remote code execution.
Detects remote printer driver load from a Detailed File Share event in Windows Security logs, which is indicative of successful exploitation attempts against the Print Spooler vulnerabilities CVE-2021-1675 (PrintNightmare) and CVE-2021-34527.
Detects the remote installation of a print driver, which is a possible indication of the exploitation of PrintNightmare (CVE-2021-1675, CVE-2021-34527). The occurrence of print drivers being installed remotely via RPC functions should be rare, as print drivers are normally installed locally or through group policy.
Detects the creation or modification of registry keys related to printer drivers that contain specific strings associated with Mimikatz or the PrinterNightmare vulnerability (CVE-2021-1675, CVE-2021-34527). The rule looks for 'QMS 810' or 'mimikatz' in printer driver paths, or a combination of 'legitprinter' and printer environment paths, or specific strings like 'Gentil Kiwi', 'mimikatz printer', or 'Kiwi Legit Printer' in registry objects related to printing.