rnsmwr-kill-switch-dtctn

name	rnsmwr-kill-switch-dtctn
description	Detects and exploits ransomware kill switch mechanisms including mutex-based execution guards, domain-based kill switches, and registry-based termination checks. Implements proactive mutex vaccination and kill switch domain monitoring to prevent ransomware from executing. Activates for requests involving ransomware kill switch analysis, mutex vaccination, WannaCry-style domain kill switches, or malware execution guard detection.
domain	cybersecurity
subdomain	ransomware-defense
tags	["ransomware","kill-switch","mutex","detection","WannaCry","malware-analysis"]
version	1.0.0
author	mahipal
license	Apache-2.0
nist_csf	["PR.DS-11","RS.MA-01","RC.RP-01","PR.IR-01"]

Implementing Ransomware Kill Switch Detection

When to Use

• Analyzing a ransomware sample to determine if it contains a kill switch mechanism (mutex, domain, registry)
• Deploying proactive mutex vaccination across endpoints to prevent known ransomware families from executing
• Monitoring DNS for kill switch domain lookups that indicate ransomware attempting to check before encrypting
• During incident response to quickly determine if a ransomware variant can be stopped by activating its kill switch
• Building detection signatures for ransomware mutex creation events using Sysmon or EDR telemetry

Do not use kill switch vaccination as a primary defense. Not all ransomware families implement kill switches, and those that do may remove them in newer versions. This is a supplementary detection and prevention layer.

Prerequisites

• Python 3.8+ with ctypes (Windows) for mutex creation and enumeration
• Sysmon installed with Event ID 1 (process creation) and Event ID 17/18 (pipe/mutex events) configured
• Access to malware analysis sandbox for identifying kill switch mechanisms in samples
• DNS monitoring capability for detecting kill switch domain resolution attempts
• Familiarity with Windows internals: mutexes (mutants), kernel objects, named pipes
• Reference database of known ransomware mutexes (github.com/albertzsigovits/malware-mutex)

Workflow

Step 1: Identify Kill Switch Mechanisms in Ransomware

Analyze samples for common kill switch patterns:

Kill Switch Types Found in Ransomware:
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
1. MUTEX-BASED (most common):
   - Ransomware creates a named mutex at startup
   - If mutex already exists → another instance is running → exit
   - Defense: Pre-create the mutex to prevent execution
   - Examples:
     WannaCry:     Global\MsWinZonesCacheCounterMutexA
     Conti:        kasKDJSAFJauisiudUASIIQWUA82
     REvil:        Global\{GUID-based-on-machine}
     Ryuk:         Global\YOURPRODUCT_MUTEX

2. DOMAIN-BASED:
   - Ransomware resolves a hardcoded domain before executing
   - If domain resolves → security sandbox detected → exit
   - Defense: Register/sinkhole the domain to activate kill switch
   - Examples:
     WannaCry v1:  iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea.com
     WannaCry v1:  fferfsodp9ifjaposdfjhgosurijfaewrwergwea.com

3. REGISTRY-BASED:
   - Check for specific registry key/value before executing
   - If key exists → exit (anti-analysis or kill switch)
   - Defense: Create the registry key proactively

4. FILE-BASED:
   - Check for existence of specific file or directory
   - If marker file exists → exit
   - Defense: Create the marker file on all endpoints

5. LANGUAGE-BASED:
   - Check system language/keyboard layout
   - Exit if Russian/CIS country keyboard detected
   - Common in Eastern European ransomware groups