Sigma detection rules, expert-reviewed

Malicious COM Hijack of PSFactoryBuffer InprocServer32

This rule detects modification of the InprocServer32 value under the CLSID {1299CF18-C4F5-4B6A-BB0F-2299F0398E27} PSFactoryBuffer key in the per-user registry hive, a COM hijack used by RomCom for persistence and execution after WinRAR exploitation. Redirecting this COM server class to an attacker DLL causes malicious code to load when the COM object is instantiated.

Malicious NTLM Downgrade Attack - Reg via SYSMON (via registry_set)

This rule detects modifies the registry configuration in order to enable or downgrade NTLM protocol version, to later on perform relay attacks.

Suspicious Replacement of termsrv DLL to Enable Concurrent RDP via file_event

This rule detects a write to the Terminal Services termsrv.dll in System32, the technique OkoBot uses to patch the RDP service and allow multiple concurrent sessions. The genuine termsrv.dll changes only through Windows servicing. An out-of-band modification indicates tampering to enable stealthy remote access.

Malicious Cicada3301 Ransomware Locker Execution via Command Line Key (via process_creation)

This rule detects execution of the Cicada3301 ransomware locker binary with its command-line decryption key argument, which the Repellent Scorpius affiliate launched remotely through PsExec to encrypt hosts. Passing the encryption key on the command line is characteristic of this Rust-based locker and indicates active ransomware deployment.

Suspicious WARMCOOKIE Scheduled Task for rundll32 Persistence via process_creation

This rule detects creation of a scheduled task that runs rundll32 against the WARMCOOKIE loader RtlUpd at a short recurring interval to maintain persistence. The backdoor registers a task firing every ten minutes to ensure continuous execution. The combination of a minute-based recurrence with rundll32 loading this DLL is characteristic of WARMCOOKIE.

Malicious Audit Policy Disabled by Command Line (via security)

This rule detects attempts disbaled the audit policy for defense evasion purposes.

NetSupport Manager RAT Execution From a User-Writable Path (via process_creation)

This rule detects the NetSupport Manager remote-control client (client32.exe) running from a user-writable directory such as AppData, ProgramData or Temp, where adversaries deploy the otherwise-legitimate RMM tool as a covert remote access trojan. Abuse of remote monitoring and management software is a leading access technique in the Red Canary Threat Detection Report. Because sanctioned installs live in Program Files, execution from user paths is a strong indicator of malicious NetSupport deployment.

Malicious Active Directory Replication Request Indicating DCSync

This rule detects a directory service access event granting the replicating directory changes right which the ALPHV actor exercised through a credential tool to perform DCSync and pull domain hashes and this matters because outside of domain controllers and a small set of sync services the request for the replication extended right is a high fidelity indicator of DCSync credential theft.

Suspicious SoftPerfect Network Scanner Execution for Discovery

This rule detects execution of the SoftPerfect Network Scanner netscan.exe used for internal network discovery. The Christmas Miracle actor ran this tool to map reachable hosts and services before lateral movement. Unsanctioned network scanning is a common precursor to broader compromise.

Suspicious UAC Bypass via iscsicpl Auto-Elevation in Operation TrueChaos

This rule detects iscsicpl.exe spawning a command interpreter or script host child process, an auto-elevation UAC bypass abused in Operation TrueChaos against Southeast Asian government targets. iscsicpl launching cmd, powershell or a temporary binary indicates privilege escalation ahead of Havoc C2 deployment.

Malicious GPO Permission Abuse via SharpGPOAbuse

This rule detects execution of SharpGPOAbuse, a tool CrazyHunter operators use to weaponize edit rights over a Group Policy Object for domain-wide code execution. Abusing GPO permissions lets an attacker push tasks or scripts to every host in scope. Presence of this tooling indicates active privilege abuse against Active Directory.

Suspicious Remote Connection to ADWS Port 9389 via security

This rule detects Windows Filtering Platform event 5156 recording an allowed inbound connection to TCP port 9389, the Active Directory Web Services port. Correlating the real source address from event 5156 exposes remote ADWS enumeration that would otherwise appear as localhost in Directory Service logs, so non-loopback connections to 9389 indicate potential SOAPHound style directory collection.

Malicious Cobalt Strike Default Named Pipe Creation (via pipe_created)

This rule detects creation of named pipes matching Cobalt Strike default and post-exploitation patterns such as msagent_, postex_ and status_ pipes used for beacon inter-process communication and privilege escalation. Cobalt Strike is among the most prevalent adversary tools in the Red Canary Threat Detection Report, used across ransomware and espionage intrusions for command and control. Detecting its characteristic named pipes surfaces beacon activity that often evades network-based controls.

Malicious SharePoint spinstall0 Webshell Dropped in LAYOUTS

This rule detects the spinstall0.aspx file being written into the SharePoint LAYOUTS directory. Attackers exploiting the ToolShell chain drop this ASPX webshell to steal machine keys and maintain access. Creation of spinstall0.aspx in LAYOUTS is a definitive post-exploitation indicator.

Suspicious Registry Run Key Persistence Masquerading as Microsoft Updater (via process_creation)

This rule detects reg.exe adding a CurrentVersion Run value named updater that points to a Microsoft Updater directory. Maranhao Stealer establishes persistence with this masqueraded autorun entry in the user AppData path.