Sigma detection rules, expert-reviewed

Suspicious Virtual Machine Detection via Registry Query (via process_creation)

This rule detects reg.exe querying the Virtual Machine Guest Parameters registry key used to fingerprint hypervisor or sandbox environments. This anti-analysis check was observed prior to Lynx ransomware deployment. Adversaries use it to decide whether to continue execution or evade automated analysis sandboxes.

Suspicious TruffleHog Secret Scanner Execution

This rule detects execution of the TruffleHog secret-scanning tool on developer or build hosts, where adversaries run it to harvest credentials and API keys from repositories and filesystems. It is associated with software supply chain attacks that repurpose legitimate developer utilities for credential theft. Detecting unexpected TruffleHog runs flags opportunistic secret collection.

Suspicious Text-File Payload Staging in Temp (via file_event)

This rule detects creation of specifically named text staging files used to hold base64-encoded .NET loaders and encrypted configuration. The SHADOW#REACTOR campaign used a text-only staging pipeline before in-memory Remcos RAT deployment.

Malicious XRed Backdoor Persistence via Synaptics Run Key (via registry_set)

This rule detects the XRed backdoor establishing persistence through a Run key value named Synaptics Pointing Device Driver that points into the ProgramData\Synaptics directory. The value name masquerades as a legitimate touchpad driver while the executable path is a non-standard ProgramData location dropped by trojanized InstantView installers. Attackers use this autorun entry to survive reboots and maintain backdoor access for keylogging and data theft.

Suspicious Mirage Kitten SspiCli.dll Search-Order Hijack via AppVShNotify.exe (via image_load)

This rule detects AppVShNotify.exe loading SspiCli.dll from outside System32, a DLL search-order hijack used by Mirage Kitten to execute malware under a trusted App-V binary against Middle East and Africa targets. Sideloading a system DLL name from an unexpected path lets the attacker run code stealthily while masquerading as a legitimate Windows component.

Malicious DLL Side-Loading of msimg32 via Silverlight.Configuration.exe

This rule detects Silverlight.Configuration.exe loading msimg32.dll from outside the Windows system directories. The Horns and Hooves campaign abused this signed binary to side-load a planted msimg32.dll and execute the NetSupport loader under a trusted process.

Suspicious Deletion of Explorer RunMRU Values

This rule detects deletion of values under the Explorer RunMRU key, an anti-forensic step in newer NetSupport RAT ClickFix loaders. The malware removed RunMRU entries to erase evidence that the victim had pasted the malicious command into the Windows Run dialog. Programmatic clearing of RunMRU history is an indicator of indicator-removal activity.

Malicious MicrosoftUpdate Run Key Persistence via Axios Compromise

This rule detects creation of a CurrentVersion Run value named MicrosoftUpdate that launches the renamed wt.exe interpreter as used by the Windows variant of the Axios supply chain RAT. The benign looking value name paired with a ProgramData interpreter path indicates masquerading persistence for the backdoor.

Suspicious New Member Added to an Exchange Administration Group - Medium Risk (via security)

This rule detects scenarios where a new member is added to a sensitive group related to Exchange server.

Suspicious CMSTP Execution With INF Payload via process_creation

This rule detects the Connection Manager Profile Installer cmstp.exe running with an INF file or silent flag, the LOLBin abused in the GST-phishing Remcos RAT chain to bypass UAC and execute attacker code. Adversaries leverage the trusted, auto-elevating cmstp binary to run malicious INF-defined commands while evading application controls, so its rare invocation is a strong signal of the multi-stage .NET infection.

Malicious NTDS Database Dump via NTDSUtil in BlackSuit Ransomware

This rule detects ntdsutil being used to create an installation from media (IFM) copy of the Active Directory database, a credential-access technique observed in BlackSuit ransomware intrusions. Dumping NTDS.dit gives operators every domain hash for offline cracking and full domain compromise, making this a critical detection.

Suspicious Scheduled Task Persistence Masquerading as OneDrive Update

This rule detects creation of a scheduled task named OneDrive Update via schtasks that runs at very short intervals and at startup, the persistence used by the GigaWiper destructive backdoor. Impersonating the OneDrive updater lets the wiper relaunch frequently while blending into expected update activity.

Malicious Regsvr32 Loading a DLL From a Data Directory (via process_creation)

This rule detects regsvr32.exe registering a DLL located in ProgramData or a user AppData directory, the loader behavior Emotet and similar malware use to execute a dropped payload under a trusted binary. Regsvr32 execution of user-dropped DLLs is a defense-evasion technique tracked in the Red Canary Threat Detection Report. Detecting these invocations surfaces malware loading from a staging directory.

Uncommon Domain Trust Discovery via Nltest (via process_creation)

This rule detects nltest.exe being used to enumerate domain controllers and domain trust relationships, a discovery step that adversaries and loaders such as those profiled in the Red Canary Threat Detection Report run to understand the Active Directory environment before moving laterally. Because interactive nltest trust enumeration is uncommon on typical endpoints, it is a useful early indicator of hands-on-keyboard reconnaissance. Detecting these queries surfaces the adversary orienting inside the domain.

Suspicious Shell Spawned by Langflow Python Process (via process_creation)

This rule detects a Langflow Python process spawning a command shell or network utility. Such a child process is consistent with the reverse shell payloads used against CVE-2025-3248. A Langflow worker does not normally launch interactive shells.