performing-malware-persistence-investigation

What this skill does

# Performing Malware Persistence Investigation

## When to Use
- When investigating how malware maintains presence on a compromised system after reboots
- During incident response to identify all persistence mechanisms for complete remediation
- For threat hunting to discover unauthorized autostart entries across endpoints
- When analyzing malware behavior to understand its persistence strategy
- For verifying that all persistence has been removed after incident remediation

## Prerequisites
- Forensic image or live system access with administrative privileges
- Autoruns (Sysinternals) for Windows persistence enumeration
- RegRipper for offline registry analysis
- Understanding of Windows and Linux persistence mechanisms
- YARA rules for scanning persistence locations
- Baseline of known-good autorun entries for comparison

## Workflow

### Step 1: Enumerate Windows Registry Persistence

```bash
# Extract registry hives from forensic image
mount -o ro,loop,offset=$((2048*512)) /cases/case-2024-001/images/evidence.dd /mnt/evidence

# Key registry persistence locations
python3 << 'PYEOF'
from Registry import Registry
import json

results = {'registry_persistence': []}

# SYSTEM hive analysis
system_reg = Registry.Registry("/cases/case-2024-001/registry/SYSTEM")
select = system_reg.open("Select")
current = select.value("Current").value()
cs = f"ControlSet{current:03d}"

# Services (very common persistence)
services = system_reg.open(f"{cs}\\Services")
for svc in services.subkeys():
    try:
        start_type = svc.value("Start").value()
        image_path = ""
        try:
            image_path = svc.value("ImagePath").value()
        except:
            pass
        # Start types: 0=Boot, 1=System, 2=Auto, 3=Manual, 4=Disabled
        if start_type in (0, 1, 2) and image_path:
            svc_type = svc.value("Type").value() if svc.values() else 0
            results['registry_persistence'].append({
                'location': f'HKLM\\SYSTEM\\{cs}\\Services\\{svc.name()}',
                'type': 'Service',
                'value': image_path,
                'start_type': start_type,
                'timestamp': str(svc.timestamp())
            })
    except Exception:
        pass

# SOFTWARE hive analysis
sw_reg = Registry.Registry("/cases/case-2024-001/registry/SOFTWARE")

# Machine Run keys
run_keys = [
    "Microsoft\\Windows\\CurrentVersion\\Run",
    "Microsoft\\Windows\\CurrentVersion\\RunOnce",
    "Microsoft\\Windows\\CurrentVersion\\RunServices",
    "Microsoft\\Windows\\CurrentVersion\\RunServicesOnce",
    "Microsoft\\Windows\\CurrentVersion\\Policies\\Explorer\\Run",
    "Wow6432Node\\Microsoft\\Windows\\CurrentVersion\\Run",
    "Wow6432Node\\Microsoft\\Windows\\CurrentVersion\\RunOnce",
]

for key_path in run_keys:
    try:
        key = sw_reg.open(key_path)
        for value in key.values():
            results['registry_persistence'].append({
                'location': f'HKLM\\SOFTWARE\\{key_path}',
                'type': 'Run Key',
                'name': value.name(),
                'value': str(value.value()),
                'timestamp': str(key.timestamp())
            })
    except Exception:
        pass

# NTUSER.DAT analysis
import glob
for ntuser in glob.glob("/cases/case-2024-001/registry/NTUSER*.DAT"):
    try:
        user_reg = Registry.Registry(ntuser)
        user_run_keys = [
            "Software\\Microsoft\\Windows\\CurrentVersion\\Run",
            "Software\\Microsoft\\Windows\\CurrentVersion\\RunOnce",
            "Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Shell Folders\\Startup",
        ]
        for key_path in user_run_keys:
            try:
                key = user_reg.open(key_path)
                for value in key.values():
                    results['registry_persistence'].append({
                        'location': f'HKCU\\{key_path}',
                        'type': 'User Run Key',
                        'name': value.name(),
                        'value': str(value.value()),
                        'timestamp': str(key.timestamp()),
                        'hive': ntuser
                    })
            except Exception:
                pass
    except Exception:
        pass

print(f"Total registry persistence entries: {len(results['registry_persistence'])}")
for entry in results['registry_persistence']:
    print(f"  [{entry['type']}] {entry.get('name', '')} -> {entry.get('value', '')[:100]}")

with open('/cases/case-2024-001/analysis/registry_persistence.json', 'w') as f:
    json.dump(results, f, indent=2)
PYEOF
```

### Step 2: Check Scheduled Tasks and WMI Persistence

```bash
# Extract scheduled tasks from forensic image
mkdir -p /cases/case-2024-001/persistence/tasks/
cp -r /mnt/evidence/Windows/System32/Tasks/* /cases/case-2024-001/persistence/tasks/ 2>/dev/null

# Parse scheduled task XML files
python3 << 'PYEOF'
import os, xml.etree.ElementTree as ET

tasks_dir = '/cases/case-2024-001/persistence/tasks/'
suspicious_tasks = []

for root_dir, dirs, files in os.walk(tasks_dir):
    for fname in files:
        fpath = os.path.join(root_dir, fname)
        try:
            tree = ET.parse(fpath)
            root = tree.getroot()
            ns = {'t': 'http://schemas.microsoft.com/windows/2004/02/mit/task'}

            actions = root.findall('.//t:Exec', ns)
            for action in actions:
                command = action.find('t:Command', ns)
                args = action.find('t:Arguments', ns)
                cmd_text = command.text if command is not None else ''
                args_text = args.text if args is not None else ''

                # Flag suspicious commands
                suspicious_indicators = [
                    'powershell', 'cmd.exe', 'wscript', 'cscript', 'mshta',
                    'regsvr32', 'rundll32', 'certutil', 'bitsadmin',
                    '/c ', '-enc', '-e ', 'hidden', 'bypass', 'downloadstring',
                    'invoke-', 'iex', '/tmp/', 'appdata', 'programdata',
                    'temp\\', '.ps1', '.vbs', '.hta', 'base64'
                ]

                is_suspicious = any(s in (cmd_text + ' ' + args_text).lower() for s in suspicious_indicators)

                task_info = {
                    'name': fname,
                    'path': fpath.replace(tasks_dir, ''),
                    'command': cmd_text,
                    'arguments': args_text,
                    'suspicious': is_suspicious
                }

                if is_suspicious:
                    suspicious_tasks.append(task_info)
                    print(f"SUSPICIOUS TASK: {fname}")
                    print(f"  Command: {cmd_text}")
                    print(f"  Arguments: {args_text}")
                    print()

        except Exception as e:
            pass

print(f"\nTotal suspicious scheduled tasks: {len(suspicious_tasks)}")
PYEOF

# Check WMI event subscriptions (common APT persistence)
# WMI repository: C:\Windows\System32\wbem\Repository\
cp -r /mnt/evidence/Windows/System32/wbem/Repository/ /cases/case-2024-001/persistence/wmi/ 2>/dev/null

# Parse WMI persistence using PyWMIPersistenceFinder
python3 << 'PYEOF'
import os, re

# Search WMI OBJECTS.DATA for event subscriptions
wmi_db = '/cases/case-2024-001/persistence/wmi/OBJECTS.DATA'
if os.path.exists(wmi_db):
    with open(wmi_db, 'rb') as f:
        data = f.read()

    # Search for EventFilter strings
    filters = re.findall(b'__EventFilter.*?(?=\x00\x00)', data)
    consumers = re.findall(b'CommandLineEventConsumer.*?(?=\x00\x00)', data)
    bindings = re.findall(b'__FilterToConsumerBinding.*?(?=\x00\x00)', data)

    print("=== WMI PERSISTENCE ===")
    print(f"Event Filters: {len(filters)}")
    print(f"Command Consumers: {len(consumers)}")
    print(f"Filter-Consumer Bindings: {len(bindings)}")

    for consumer in consumers:
        decoded = consumer.decode('utf-8', errors='ignore')
        print(f"  Consumer: {decoded[:200]}")
else:
    print("WMI repository not