Malware Dynamic Analysis

Malware Dynamic Analysis

Safely execute and comprehensively monitor malware behavior in isolated environments for professional malware research and enterprise security operations.

When to Use This Skill

Use this skill when you need to:

• Execute malware safely in an isolated environment
• Monitor runtime behavior (processes, files, registry, network)
• Capture and analyze network traffic and C2 communications
• Validate hypotheses from static analysis
• Extract runtime-decrypted strings or configurations
• Document actual malware functionality for reports
• Create behavioral IOCs and detection signatures
• Analyze process injection and code execution techniques

⚠️ Safety First - Pre-Execution Checklist

CRITICAL: Never execute malware outside a properly isolated environment.

Before ANY execution:

• Snapshot taken of clean VM state
• Network isolated (host-only or INetSim simulation)
• No shared folders enabled
• No clipboard sharing
• Time sync disabled
• Monitoring tools ready and running
• Analysis persona active (no personal info)
• Emergency shutdown plan ready

If ANY checkbox fails - DO NOT EXECUTE

Dynamic Analysis Workflow

Phase 1: Environment Preparation (10 minutes)

1. Verify VM Isolation:

# Check network adapter settings
# Should be: Host-only or NAT with INetSim

# Test internet connectivity (should fail or hit INetSim)
ping 8.8.8.8
nslookup google.com

# Verify no shared folders
net use  # Windows
df -h    # Linux

# Check time sync (should be disabled)
w32tm /query /status  # Windows

2. Start Monitoring Tools:

Launch in this order:

1. Procmon (Process Monitor) - File/Registry/Process activity
2. Wireshark - Network traffic capture
3. System Informer - Process/memory monitoring
4. Regshot - Take "before" snapshot (optional)

See references/tool_setup.md for detailed configuration.

3. Establish Baseline:

• Take note of running processes
• Document open network connections
• Record current registry state (if using Regshot)

Phase 2: Malware Execution (Variable Duration)

Execute the Sample:

# For PE executables
.\sample.exe

# With arguments (if required)
.\sample.exe /install /silent

# For DLLs
rundll32.exe sample.dll,DllMain
rundll32.exe sample.dll,ExportedFunction

# For scripts
powershell.exe -ExecutionPolicy Bypass -File sample.ps1
cscript.exe //NoLogo sample.vbs
wscript.exe sample.js

Observation Duration:

• Minimum: 5 minutes (most malware acts quickly)
• Standard: 15 minutes (catch delayed execution)
• Extended: 60+ minutes (for time-based evasion)

What to Watch:

• New processes spawned
• Network connections initiated
• Files created/modified/deleted
• Registry keys modified
• CPU/Memory usage spikes
• Pop-ups or UI changes
• Error messages

Phase 3: Process Monitoring

Using System Informer:

Track New Processes:

1. Watch for new entries in process list
2. Note parent-child relationships
3. Document command-line arguments
4. Check process integrity levels
5. Monitor memory allocations

Identify Process Injection:

• Look for RWX (Read-Write-Execute) memory regions
• Check for threads in unexpected processes
• Monitor for process hollowing indicators
• Watch for CreateRemoteThread calls

Memory Analysis:

Right-click process → Memory → Inspect
Look for:
- Suspicious memory regions (RWX permissions)
- Injected DLLs (not in system path)
- Decoded strings in memory
- Configuration data

Right-click process → Create Dump File
→ Save for later Volatility analysis

Handles Analysis:

Double-click process → Handles tab

Look for:
- Mutexes (process synchronization objects)
- Named pipes (inter-process communication)
- File handles (what files are open)
- Registry key handles

Phase 4: File System Monitoring

Using Procmon (Process Monitor):

Configure Filters:

Filter → Add:
- Process Name → is → sample.exe → Include
- Operation → contains → File → Include
- Operation → contains → Reg → Include
- Process Name → is → explorer.exe → Exclude
- Process Name → is → svchost.exe → Exclude (unless suspicious)

Monitor File Operations:

Look for:

• CreateFile - Files being created
• WriteFile - Files being modified
• DeleteFile - Files being deleted
• SetRenameInformationFile - Files being renamed

Key Locations to Watch:

C:\Users\<user>\AppData\Local\Temp\
C:\Users\<user>\AppData\Roaming\
C:\ProgramData\
C:\Windows\Temp\
C:\Users\<user>\AppData\Local\

Extract Dropped Files:

# Find recently created files (last 5 minutes)
Get-ChildItem -Path C:\ -Recurse -ErrorAction SilentlyContinue |
  Where-Object {$_.CreationTime -gt (Get-Date).AddMinutes(-5)}

# Hash all dropped files
Get-ChildItem -Path C:\Users\<user>\AppData\Local\Temp\ |
  Get-FileHash -Algorithm SHA256 |
  Format-Table Hash, Path

Save Evidence:

• Copy dropped files to evidence folder
• Calculate hashes
• Document file paths and timestamps
• Preserve file metadata

Phase 5: Registry Monitoring

Using Procmon:

Filter for Registry Operations:

Operation → contains → Reg → Include

Common Registry Operations:

• RegCreateKey - Creating new keys
• RegSetValue - Writing values
• RegQueryValue - Reading values
• RegDeleteKey - Deleting keys

Critical Registry Locations:

Persistence Mechanisms:

HKCU\Software\Microsoft\Windows\CurrentVersion\Run
HKLM\Software\Microsoft\Windows\CurrentVersion\Run
HKCU\Software\Microsoft\Windows\CurrentVersion\RunOnce
HKLM\Software\Microsoft\Windows\CurrentVersion\RunOnce
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
HKLM\System\CurrentControlSet\Services (new services)

Configuration Storage:

HKCU\Software\<malware_name>
HKLM\Software\<malware_name>

Manual Registry Inspection:

# Export specific key for analysis
reg export "HKCU\Software\Microsoft\Windows\CurrentVersion\Run" run_keys.reg

# Query specific value
reg query "HKCU\Software\Microsoft\Windows\CurrentVersion\Run"

Using Regshot (Alternative):

1. Take 1st shot (before execution)
2. Execute malware
3. Take 2nd shot (after execution)
4. Compare → generates HTML report of all changes

Phase 6: Network Behavior Analysis

Using Wireshark:

Start Capture:

Capture → Options → Select network adapter → Start

Display Filters:

# DNS queries
dns

# HTTP traffic
http

# HTTPS/TLS
tls

# Specific IP address
ip.addr == 192.168.1.100

# Specific port
tcp.port == 443 || udp.port == 443

What to Capture:

DNS Queries:

# Extract all DNS queries
tshark -r capture.pcapng -Y dns.qry.name -T fields -e dns.qry.name | sort -u

Look for:
- Domain names contacted
- DGA (Domain Generation Algorithm) patterns
- Fast-flux DNS indicators
- Known C2 domains

HTTP/HTTPS Traffic:

# Extract HTTP requests
tshark -r capture.pcapng -Y http.request -T fields -e http.host -e http.request.uri

# Extract User-Agent strings
tshark -r capture.pcapng -Y http -T fields -e http.user_agent | sort -u

Look for:
- C2 server URLs
- Download locations
- POST data (exfiltration)
- Suspicious User-Agents
- Beacon patterns (regular intervals)

TCP/UDP Connections:

# Real-time connection monitoring
netstat -ano | findstr ESTABLISHED

# Using TCPView (Sysinternals)
tcpview.exe

Look for:
- Destination IPs and ports
- Connection frequency (beaconing)
- Data transfer volumes
- Unusual protocols

Analyze Network Patterns:

C2 Communication:

• Regular beacon intervals (e.g., every 60 seconds)
• Consistent packet sizes
• Encrypted payloads
• Known C2 infrastructure

Data Exfiltration:

• Large outbound transfers
• POST requests with encoded data
• DNS tunneling (large TXT records)
• Non-standard protocols

Extract Network IOCs:

# All contacted IPs
tshark -r capture.pcapng -T fields -e ip.dst | sort -u | grep -v "192.168\|10.0\|127.0"

# All contacted domains
tshark -r capture.pcapng -Y dns -T fields -e dns.qry.name | sort -u

# All URLs
tshark -r capture.pcapng -Y http.request -T fields -e http.host -e http.request.uri |
  awk '{print "http://"$1$2}'

Phase 7: Advanced Monitoring

Using Sysmon (Windows Event Logging):

Setup:

# Install with SwiftOnSecurity config
sysmon64.exe -accepteula -i sysmonconfig.xml

# View logs
Get-WinEvent -LogName "Microsoft-Windows-Sysmon/Operational" -MaxEvents 100 | Format-List

Key Event IDs:

• Event ID 1 - Process Creation
• Event ID 3 - Network Connection
• Event ID 5 - Process Terminated
• Event ID 7 - Image Loaded (DLL)
• Event ID 8 - CreateRemoteThread (injection)
• Event ID 10 - Process Access
• Event ID 11 - File Created
• Event ID 12/13 - Registry Events

Query Specific Events:

# Process creation events
Get-WinEvent -FilterHashtable @{LogName='Microsoft-Windows-Sysmon/Operational'; ID=1} |
  Format-List

# Network connections
Get-WinEvent -FilterHashtable @{LogName='Microsoft-Windows-Sysmon/Operational'; ID=3} |
  Format-List

# Export for analysis
wevtutil epl Microsoft-Windows-Sysmon/Operational C:\evidence\sysmon_logs.evtx

Using Noriben (Automated Procmon):

# Run Noriben with automatic malware execution
python Noriben.py --cmd sample.exe --timeout 300

# Output: Noriben_<timestamp>.txt with parsed behavior summary

Benefits:

• Automates Procmon collection
• Filters noise automatically
• Generates readable report
• Timestamps all activities

Phase 8: Persistence Analysis

Check All Persistence Mechanisms:

Run Keys:

# Current User
Get-ItemProperty -Path "HKCU:\Software\Microsoft\Windows\CurrentVersion\Run"

# Local Machine
Get-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\Run"

# RunOnce keys
Get-ItemProperty -Path "HKCU:\Software\Microsoft\Windows\CurrentVersion\RunOnce"
Get-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\RunOnce"

Scheduled Tasks:

Get-ScheduledTask | Where-Object {$_.TaskName -notlike "Microsoft*"} | Format-Table

# Detailed task info
Get-ScheduledTask -TaskName "SuspiciousTask" | Get-ScheduledTaskInfo

Services:

# Recently created services
Get-Service | Where-Object {$_.StartType -ne "Disabled"} | Format-Table

# Service details
sc query <service_name>
sc qc <service_name>

Startup Folder:

# Check startup folders
dir "$env:APPDATA\Microsoft\Windows\Start Menu\Programs\Startup"
dir "$env:PROGRAMDATA\Microsoft\Windows\Start Menu\Programs\Startup"

WMI Event Subscriptions:

Get-WmiObject -Namespace root\Subscription -Class __EventFilter
Get-WmiObject -Namespace root\Subscription -Class __EventConsumer
Get-WmiObject -Namespace root\Subscription -Class __FilterToConsumerBinding

Phase 9: Artifact Collection

Export All Evidence:

Process Monitor:

File → Save → All Events → CSV format
→ Save as: procmon_output.csv

Wireshark:

File → Export Specified Packets → All packets
→ Save as: network_capture.pcapng

System Informer:

File → Save All → processes.txt
(Optional) Right-click process → Create dump file → memory_dump.dmp

Regshot:

Compare → Output to HTML
→ Save as: registry_changes.html

Sysmon Logs:

wevtutil epl Microsoft-Windows-Sysmon/Operational C:\evidence\sysmon.evtx

Dropped Files:

# Copy all dropped files with hashes
$evidence = "C:\evidence\dropped_files"
New-Item -Path $evidence -ItemType Directory -Force

Get-ChildItem -Path "C:\Users\<user>\AppData\Local\Temp" |
  ForEach-Object {
    Copy-Item $_.FullName -Destination $evidence
    Get-FileHash $_.FullName -Algorithm SHA256
  }

Screenshots:

• Take screenshots of any visible UI
• Capture error messages
• Document unusual behavior

Phase 10: Cleanup and Reset

Before Reverting VM:

1. ✅ All evidence exported and saved
2. ✅ Hashes calculated for all artifacts
3. ✅ Network captures saved
4. ✅ Process dumps saved (if needed)
5. ✅ Screenshots organized

Revert to Clean Snapshot:

VMware: VM → Snapshot → Revert to Snapshot
VirtualBox: Machine → Close → Restore current snapshot

Verify Clean State:

• Check no malware artifacts remain
• Verify monitoring tools reset
• Confirm network settings correct

Automated Sandbox Analysis

ANY.RUN (Interactive Cloud Sandbox)

When to Use:

• Need quick behavioral analysis
• Want to interact with malware during execution
• Need visual demonstration of behavior
• Time-constrained analysis

Workflow:

1. Upload sample to https://app.any.run
2. Select Windows version (7/8/10/11)
3. Choose network simulation (Internet or No connection)
4. Click "Run"
5. Interact if needed (click buttons, enter passwords)
6. Monitor real-time:
   • Process tree
   • Network requests
   • File operations
   • Registry changes
7. Download artifacts:
   • PCAP file
   • Process dumps
   • Dropped files
   • IOCs (JSON/CSV)

Advantages:

• Fast results (5-10 minutes)
• Visual process tree
• Archived for future reference
• No local resources needed

Limitations:

• Sample uploaded to cloud (privacy concern)
• VM-aware malware may not execute
• Limited to preset Windows versions

Joe Sandbox / Hybrid Analysis

API Submission (if available):

# Submit to Joe Sandbox
jbxapi submit sample.exe --systems win10x64

# Check status
jbxapi status <submission_id>

# Download report
jbxapi download <submission_id> --type html > joe_report.html
jbxapi download <submission_id> --type json > joe_report.json

Report Analysis:

• Behavior summary
• Network communications
• File system changes
• Screenshots
• MITRE ATT&CK mapping
• YARA rule suggestions

Local Sandboxes (CAPE, Cuckoo)

For Enterprise/Private Analysis:

• Complete control over environment
• No sample disclosure
• Customizable VM configurations
• Automated at scale

See references/sandbox_setup.md for local sandbox installation.

Common Dynamic Analysis Scenarios

Scenario 1: Ransomware Execution

Preparation:

• Create test files in common locations
• Monitor C:\Users<user>\Documents closely
• Watch for file extension changes

Observe:

• File encryption activity
• Ransom note creation
• Desktop wallpaper changes
• Process names (often legitimate-sounding)

Capture:

• Screenshot of ransom note
• List of encrypted file extensions
• C2 communication (if any)
• Bitcoin wallet addresses

Scenario 2: Trojan/RAT Behavior

Preparation:

• Set up fake C2 listener (ncat)
• Monitor for reverse shell attempts

Observe:

• Persistence mechanism creation
• C2 beacon intervals
• Command execution
• Keylogging indicators
• Screen capture attempts

Capture:

• C2 traffic (PCAP)
• Executed commands
• Exfiltrated data
• Persistence registry keys

Scenario 3: Dropper/Loader Analysis

Preparation:

• Monitor network for secondary payload downloads
• Watch temp directories closely

Observe:

• Initial dropper execution
• Secondary payload download
• Payload execution
• Cleanup of dropper

Capture:

• All dropped files and hashes
• Download URLs
• Full execution chain (parent → child processes)

Scenario 4: Infostealer Execution

Preparation:

• Populate browser with test credentials
• Create test cryptocurrency wallets
• Add test email client

Observe:

• Browser profile access
• Credential file reads
• Data staging (zip/archive creation)
• Exfiltration attempts

Capture:

• Accessed credential stores
• Exfiltration destinations
• Data encoding methods

Behavioral IOC Extraction

From Dynamic Analysis, Extract:

Process IOCs:

Process Name: sample.exe
Parent Process: explorer.exe
Command Line: C:\Users\Public\sample.exe /install
Child Processes: cmd.exe, powershell.exe
Mutex: Global\UniqueMalwareMutex

File IOCs:

Created Files:
- C:\Users\<user>\AppData\Local\Temp\payload.exe (SHA256: abc123...)
- C:\ProgramData\config.dat

Modified Files:
- C:\Users\<user>\Documents\*.locked (ransomware)

Deleted Files:
- %TEMP%\dropper.exe (self-deletion)

Registry IOCs:

Created Keys:
HKCU\Software\Microsoft\Windows\CurrentVersion\Run\WindowsDefender
  Value: C:\Users\Public\malware.exe

Modified Keys:
HKLM\System\CurrentControlSet\Services\<new_service>

Network IOCs:

DNS Queries:
- malicious-c2[.]com
- backup-server[.]tk

HTTP Requests:
- hxxp://malicious-c2[.]com/api/checkin
  User-Agent: Mozilla/4.0 (compatible; MSIE 6.0)

IP Connections:
- 192.168.1.100:443 (C2 server)
- 10.0.0.50:8080 (data exfiltration)

Quality Checklist

Before concluding dynamic analysis:

Execution Environment:

• VM properly isolated (verified)
• All monitoring tools captured data
• Execution time sufficient (15+ minutes minimum)
• Clean snapshot available for re-analysis

Process Monitoring:

• All spawned processes documented
• Process tree captured
• Command-line arguments recorded
• Process injection observed (if any)
• Memory dumps saved (if relevant)

File System:

• All dropped files identified and hashed
• File paths documented
• Dropped files saved to evidence
• File modifications logged
• Deletion activities recorded

Registry:

• Persistence mechanisms identified
• Registry changes documented
• Configuration keys noted
• Registry export saved

Network:

• Full PCAP captured
• DNS queries extracted
• C2 servers identified
• Network protocols documented
• Data exfiltration noted

Evidence Collection:

• All artifacts exported
• Hashes calculated
• Timestamps recorded (UTC)
• Screenshots saved
• Logs organized in case folder

Analysis Completeness:

• Behaviors match static analysis predictions
• Unexpected behaviors investigated
• IOCs validated and defanged
• Findings documented for report

Best Practices

Do:

• Always take VM snapshot before execution
• Run monitoring tools BEFORE executing malware
• Document observations in real-time
• Capture evidence continuously
• Verify network isolation
• Use multiple monitoring tools
• Save everything (disk is cheap)
• Test IOCs for accuracy
• Document timeline of events

Don't:

• Execute without proper isolation
• Trust timestamps from malware
• Assume short execution time is sufficient
• Execute on production systems (NEVER!)
• Share VM with other activities
• Enable internet without INetSim
• Forget to export evidence before reverting
• Rely on single monitoring tool
• Skip documentation during execution

Time-Based Evasion:

• Some malware delays execution (sleep evasion)
• Set extended observation period (60+ minutes)
• Monitor for scheduled tasks
• Check for triggers (time, date, system events)

VM Detection Evasion:

• Some malware detects VMs and doesn't execute
• Use pafish-free VM configurations
• Modify VM artifacts (MAC addresses, system info)
• See references/anti_analysis_bypass.md

Integration with Report Writing

Dynamic analysis provides:

• Execution Flow → Report: Technical Analysis section
• Process Activity → Report: Behavior Analysis
• Network IOCs → Report: Network Indicators
• File IOCs → Report: File Indicators
• Persistence → Report: Persistence Mechanisms
• Screenshots → Report: Appendix
• Timeline → Report: Execution Timeline

Use findings to:

• Validate static analysis hypotheses
• Create behavioral YARA rules
• Write Sigma detection rules
• Develop hunting queries
• Document MITRE ATT&CK techniques

Tool Reference

For detailed tool setup, filtering, and configuration:

• references/tool_setup.md - Procmon, Wireshark, System Informer configuration
• references/sandbox_setup.md - Local sandbox installation
• references/anti_analysis_bypass.md - Bypassing VM detection and sleep evasion

Example Usage

User request: "Help me safely execute this ransomware sample and document its behavior"

Workflow:

1. Verify VM isolation and safety checklist
2. Guide monitoring tool setup (Procmon, Wireshark, System Informer)
3. Execute sample with observation
4. Document process creation and injection
5. Capture file encryption behavior
6. Extract ransom note and C2 communications
7. Collect all artifacts
8. Generate behavioral IOCs
9. Create timeline of execution
10. Prepare findings for report integration