Sigma detection rules, expert-reviewed

Malicious RDP Session Hijacking via tscon Command Line

This rule detects execution of the native tscon.exe binary with a destination session and an rdp-tcp or console source argument, the living-off-the-land technique used to hijack another user's Remote Desktop session without their credentials. Adversaries with SYSTEM privileges connect an existing session to their own to inherit the victim's access for lateral movement and privilege escalation. Interactive tscon usage targeting another session is rarely legitimate.

Malicious Curl Download From C2 CAPTCHA Path via Process Creation

This rule detects curl.exe retrieving a payload using the misspelled /capcha URL path pattern used by the KongTuke fake-CAPTCHA campaign documented by Cisco Talos. The tool is invoked by a PowerShell downloader to pull the next stage from hardcoded command-and-control infrastructure. Detecting it identifies active second-stage retrieval over an attacker-controlled channel.

Suspicious Group Discovery - PowerShell (via powershell)

This rule detects enumerate local or domain groups via PowerShell.

Suspicious PowerShell History Logging Disabled via PSReadLine (via process_creation)

This rule detects PSReadLine being configured to save no command history via Set-PSReadLineOption with SaveNothing, a defense-evasion action observed with the TinyTurla-NG backdoor. Disabling history persistence removes a valuable forensic record of attacker PowerShell activity.

Malicious Impacket SMBexec Service Registration - Native (via security)

This rule detects register the SMBexec service to estasblish persistence. Note that service registration is not always performed and that is recommended to use the related registry SYSMON rule to increase detection reliability.

Suspicious Creation of PowerShell Profile Script for Persistence

This rule detects creation or modification of a PowerShell profile script. Backdoors abuse the automatic execution of the profile file on every PowerShell launch to gain stealthy persistence, running an obfuscated loader each time a session starts.

Malicious PPL Abuse via ClipUp Protected Process Launch

This rule detects the ClipUp.exe utility launched with a protected process light argument, the technique RONINGLOADER uses to spawn a signed binary as a PPL and disable Microsoft Defender. Abusing ClipUp to obtain a protected process lets the loader tamper with security services that normally block it.

Suspicious Host.exe In Windows Directory Running As Service

This rule detects execution of host.exe from the Windows directory with a service-style command line switch. BlackByte ransomware operators deployed C:\Windows\host.exe run with an -s flag and an eight-digit token to register itself as a service. A generically named binary placed in the Windows root and launched as a service is a masquerading and persistence pattern used to blend malicious execution into the OS.

Malicious Command Execution Spawned by Apache Tomcat

This rule detects the Tomcat service process spawning command interpreters or administrative utilities, indicating web application remote code execution such as the Samsung MagicINFO exploitation observed by eSentire. A Java web server launching cmd, PowerShell, or account management binaries is a strong sign of server-side exploitation leading to cryptomining deployment.

Malicious In-Memory Payload Execution via PowerShell DownloadString (via process_creation)

This rule detects PowerShell downloading a script from a remote host and immediately executing it in memory using DownloadString together with Invoke-Expression, a fileless technique used by a ransomware actor after ColdFusion exploitation to run Cobalt Strike beacons and reverse shells. Combining a web download with immediate expression evaluation is a common malicious loader pattern.

Suspicious DNS Zone Export via dnscmd for Reconnaissance

This rule detects use of dnscmd with the zone export option to dump an Active Directory DNS zone to a file, a reconnaissance technique used by the Karakurt extortion actor to enumerate internal hosts and services. A full zone export gives an attacker a map of the environment to plan lateral movement and target high-value systems.

Suspicious DLL Sideloading via Renamed fixmapi Swom.exe Loading Mapistub.dll via Confucius (via image_load)

This rule detects Confucius persistence in which the legitimate fixmapi.exe is copied to Swom.exe in AppData and side loads a malicious Mapistub.dll from LocalAppData. The genuine Mapistub.dll is a system component so loading it beside a renamed fixmapi binary indicates the loader. This chain establishes the backdoor.

Suspicious Network Scanning Tool Execution

This rule detects execution of network and port scanning utilities such as SoftPerfect Netscan and Advanced Port or IP Scanner that were used for internal reconnaissance as described in NCC Group Fivehands ransomware research. Adversaries run these scanners after initial access to map reachable hosts and services before lateral movement so their presence on servers or non administrator hosts is suspicious.

Malicious User Account Control Bypass via Auto-Elevating Binary Hijack (via process_creation)

This rule detects a known auto-elevating Windows binary such as fodhelper, computerdefaults, eventvwr or sdclt spawning a command shell or script interpreter, the tell-tale child-process pattern of a User Account Control bypass. UAC bypasses are a recurring privilege-escalation and defense-evasion technique in the Red Canary Threat Detection Report, letting adversaries obtain a high-integrity process without a prompt. Detecting these parent-child pairs surfaces the elevation attempt.

Suspicious Execution of agent.exe From WinSyncDefender AppData Directory (via process_creation)

This rule detects execution of agent.exe from the Microsoft WinSyncDefender folder under AppData Roaming, the staging path used by Operation ShadowRecruit to host its SheetAgent RAT payload. Running a generically named binary from a fake Microsoft directory in a user-writable location is a wrong-context indicator of the recruitment-themed campaign against Indian job seekers, exposing the malware between delivery and Google Sheets C2.