Sigma detection rules, expert-reviewed

Suspicious Run Key Persistence Masquerading as Edge Updater

This rule detects a Run key named EdgeUpdater whose value points into the user AppData directory. The Blitz malware creates this entry to masquerade as a legitimate Microsoft Edge updater while referencing a payload in a user-writable location. The mismatch between a trusted name and an untrusted path indicates masquerading persistence.

Suspicious PowerShell Locating and Running MSBuild Project (via process_creation)

This rule detects a PowerShell one-liner that recursively searches for msbuild.exe and downloads a project file into ProgramData for execution. This ClickFix style command was observed in the PHALT#BLYX campaign.

Malicious COM Object Hijack Pointing to IconCache DLL

This rule detects a COM object InProcServer32 registration whose default value references an iconcache prefixed DLL in the Explorer directory. Operation ForumTroll established persistence via a COM hijack under HKCR CLSID InProcServer32 pointing at its payload DLL as documented by Kaspersky. This combination of a COM handler mapped to a masquerading DLL path indicates stealthy persistence and defense evasion.

TAG-144 Dynamic DNS C2 Resolution via Structured DuckDNS Subdomain (via dns_query)

This rule detects DNS resolution of TAG-144 command-and-control hosts using the campaign envio dynamic-DNS naming scheme on duckdns.org, matching the structured envio prefix with a short numeric suffix. Adversaries leverage dynamic DNS to rotate resilient C2 endpoints, making the specific subdomain pattern a useful command-and-control indicator.

Suspicious WScript Executing VBScript from Masqueraded File Extension

This rule detects wscript.exe running a VBScript engine against files with non-script extensions such as drv, regtrans-ms or ntuser.dat, an execution and masquerading technique used by Shuckworm to hide its GammaSteel loader.

Masquerading Firewall Allow Rule Masquerading as Windows Defender Update Service via Netsh (via process_creation)

This rule detects netsh adding an advfirewall rule named to impersonate a Windows Defender update service, a defense-evasion step in the Salat Stealer chain that whitelists its own network traffic. Adversaries leverage a benign-looking firewall rule name to allow C2 and exfiltration traffic while blending into legitimate configuration, so this behavior warrants review alongside surrounding activity.

Web Server Worker Process Spawning Command Interpreter

This rule detects the IIS worker process w3wp.exe spawning command shells or administrative utilities, behavior consistent with the China Chopper web shell used in Operation Soft Cell against telecommunications providers. A web server worker launching cmd, wmic or PowerShell strongly indicates web shell command execution.

Malicious Akira Ransomware Encryption Execution (via process_creation)

This rule detects the Akira ransomware encryptor invoked with its characteristic path and share targeting switches. These combined command-line flags drive selective encryption across local and network locations. Detection here indicates active encryption and imminent impact on the environment.

Malicious PowerShell AMSI Bypass via AmsiInitFailed Command Line

This rule detects the amsiInitFailed AMSI-bypass string in a PowerShell command line, a defense-evasion technique used after Citrix Bleed exploitation to disable script scanning before running the LockBit toolkit. Setting amsiInitFailed forces AMSI to skip inspection. Detecting the string exposes an active attempt to blind endpoint script scanning.

Malicious DLL Side-Loading via AVGApplicationFrameHost

This rule detects the AVGApplicationFrameHost.exe binary loading a wsc.dll module, a DLL side-loading chain used by TheWizards APT group to execute the WizardNet backdoor alongside an encrypted log.dat shellcode payload. Abusing a signed AV-related host process to load an attacker DLL evades trust controls and blends malicious execution into legitimate software.

Suspicious PowerShell Self-Delete Of Executable via Process Creation

This rule detects PowerShell used to delete an executable in a wait-and-retry loop. Rhysida ransomware removes its own binary after execution using a PowerShell routine that loops on Test-Path and Start-Sleep until the file is gone, eliminating forensic artifacts.

Suspicious Script Host Execution of JavaScript From a User-Writable Directory (via process_creation)

This rule detects wscript.exe or cscript.exe running a .js or .jse file from a user-writable location such as AppData or Temp, the delivery-and-execution pattern behind JavaScript loaders like Gootloader that arrive through SEO-poisoned downloads. Malicious script-host execution from user directories is a recurring initial-access and execution behavior in the Red Canary Threat Detection Report. Detecting it surfaces the loader stage before it fetches and runs a second-stage payload.

Malicious Logon Script Persistence via UserInitMprLogonScript

This rule detects the creation or modification of the UserInitMprLogonScript value under the user Environment key, a logon persistence technique observed in a martial-law-themed APT campaign that pointed this value at updater.exe to execute at each logon. It captures the abuse of a rarely used logon-script registry entry to survive reboots. Detecting this is important because UserInitMprLogonScript is almost never set by legitimate software and is a well-known persistence primitive.

Malicious Boot Recovery Disable via Bcdedit (via process_creation)

This rule detects bcdedit being used to disable Windows recovery or force boot into ignore-all-failures or safe mode. Ransomware alters the boot configuration so that automatic repair and recovery options cannot restore the system after encryption. Tampering with boot recovery settings from the command line is a strong impact indicator.

Malicious Fileless JavaScript Execution via Deno Data URI (via process_creation)

This rule detects the Deno runtime executing an inline base64 encoded JavaScript payload passed as a data application javascript URI, a fileless execution technique used by attackers abusing alternative runtime environments to evade disk based detection. The allow all flag combined with an inline data URI is a strong indicator of malicious in memory code execution.