collecting-volatile-evidence-from-compromised-host

Collecting Volatile Evidence from Compromised Hosts

When to Use

• Security incident confirmed and compromised host identified
• Before system isolation, shutdown, or remediation begins
• Memory-resident malware suspected (fileless attacks)
• Need to capture network connections, running processes, and system state
• Legal proceedings may require forensic evidence preservation
• Incident requires root cause analysis with volatile data

Prerequisites

• Forensic collection toolkit on USB or network share (trusted tools)
• WinPmem/LiME for memory acquisition
• Write-blocker or forensic workstation for disk imaging
• Chain of custody documentation forms
• Secure evidence storage with integrity verification
• Authorization to collect evidence (legal/HR approval for insider cases)

Workflow

Step 1: Prepare Collection Environment

# Mount forensic USB toolkit (do NOT install tools on compromised system)
# Verify toolkit integrity
sha256sum /mnt/forensic_usb/tools/* > /tmp/toolkit_hashes.txt
diff /mnt/forensic_usb/tools/known_good_hashes.txt /tmp/toolkit_hashes.txt

# Create evidence output directory with timestamps
EVIDENCE_DIR="/mnt/evidence/$(hostname)_$(date +%Y%m%d_%H%M%S)"
mkdir -p "$EVIDENCE_DIR"
echo "Collection started: $(date -u)" > "$EVIDENCE_DIR/collection_log.txt"
echo "Collector: $(whoami)" >> "$EVIDENCE_DIR/collection_log.txt"
echo "System: $(hostname)" >> "$EVIDENCE_DIR/collection_log.txt"

Step 2: Capture System Memory (Highest Volatility)

# Windows - WinPmem memory acquisition
winpmem_mini_x64.exe "$EVIDENCE_DIR\memdump_$(hostname).raw"

# Linux - LiME kernel module for memory acquisition
insmod /mnt/forensic_usb/lime.ko "path=$EVIDENCE_DIR/memdump_$(hostname).lime format=lime"

# Linux - Alternative using /proc/kcore
dd if=/proc/kcore of="$EVIDENCE_DIR/kcore_dump.raw" bs=1M

# macOS - osxpmem
osxpmem -o "$EVIDENCE_DIR/memdump_$(hostname).aff4"

# Hash the memory dump immediately
sha256sum "$EVIDENCE_DIR/memdump_"* > "$EVIDENCE_DIR/memory_hash.sha256"

Step 3: Capture Network State

# Active network connections
# Windows
netstat -anob > "$EVIDENCE_DIR/netstat_connections.txt" 2>&1
Get-NetTCPConnection | Export-Csv "$EVIDENCE_DIR/tcp_connections.csv" -NoTypeInformation
Get-NetUDPEndpoint | Export-Csv "$EVIDENCE_DIR/udp_endpoints.csv" -NoTypeInformation

# Linux
ss -tulnp > "$EVIDENCE_DIR/socket_stats.txt"
netstat -anp > "$EVIDENCE_DIR/netstat_all.txt" 2>/dev/null
cat /proc/net/tcp > "$EVIDENCE_DIR/proc_net_tcp.txt"
cat /proc/net/udp > "$EVIDENCE_DIR/proc_net_udp.txt"

# ARP cache
arp -a > "$EVIDENCE_DIR/arp_cache.txt"

# Routing table
route print > "$EVIDENCE_DIR/routing_table.txt"  # Windows
ip route show > "$EVIDENCE_DIR/routing_table.txt"  # Linux

# DNS cache
ipconfig /displaydns > "$EVIDENCE_DIR/dns_cache.txt"  # Windows
# Linux: varies by resolver, check systemd-resolve or nscd
systemd-resolve --statistics > "$EVIDENCE_DIR/dns_stats.txt" 2>/dev/null

# Active firewall rules
netsh advfirewall show allprofiles > "$EVIDENCE_DIR/firewall_rules.txt"  # Windows
iptables -L -n -v > "$EVIDENCE_DIR/iptables_rules.txt"  # Linux

Step 4: Capture Running Processes

# Windows - Detailed process list
tasklist /V /FO CSV > "$EVIDENCE_DIR/process_list_verbose.csv"
wmic process list full > "$EVIDENCE_DIR/wmic_process_full.txt"
Get-Process | Select-Object Id,ProcessName,Path,StartTime,CPU,WorkingSet |
  Export-Csv "$EVIDENCE_DIR/ps_processes.csv" -NoTypeInformation

# Windows - Process with command line and parent
wmic process get ProcessId,Name,CommandLine,ParentProcessId,ExecutablePath /FORMAT:CSV > \
  "$EVIDENCE_DIR/process_commandlines.csv"

# Linux - Full process tree
ps auxwwf > "$EVIDENCE_DIR/process_tree.txt"
ps -eo pid,ppid,user,args --forest > "$EVIDENCE_DIR/process_forest.txt"
cat /proc/*/cmdline 2>/dev/null | tr '\0' ' ' > "$EVIDENCE_DIR/proc_cmdline_all.txt"

# Process modules/DLLs loaded
# Windows
listdlls.exe -accepteula > "$EVIDENCE_DIR/loaded_dlls.txt"
# Linux
for pid in $(ls /proc/ | grep -E '^[0-9]+$'); do
  echo "=== PID $pid ===" >> "$EVIDENCE_DIR/proc_maps.txt"
  cat "/proc/$pid/maps" 2>/dev/null >> "$EVIDENCE_DIR/proc_maps.txt"
done

# Open file handles
handle.exe -accepteula > "$EVIDENCE_DIR/open_handles.txt"  # Windows (Sysinternals)
lsof > "$EVIDENCE_DIR/open_files.txt"  # Linux

Step 5: Capture Logged-in Users and Sessions

# Windows
query user > "$EVIDENCE_DIR/logged_in_users.txt"
query session > "$EVIDENCE_DIR/active_sessions.txt"
net session > "$EVIDENCE_DIR/net_sessions.txt" 2>&1
net use > "$EVIDENCE_DIR/mapped_drives.txt" 2>&1

# Linux
who > "$EVIDENCE_DIR/who_output.txt"
w > "$EVIDENCE_DIR/w_output.txt"
last -50 > "$EVIDENCE_DIR/last_logins.txt"
lastlog > "$EVIDENCE_DIR/lastlog.txt"
cat /var/log/auth.log | tail -200 > "$EVIDENCE_DIR/recent_auth.txt" 2>/dev/null

Step 6: Capture System Configuration State

# System time (critical for timeline)
date -u > "$EVIDENCE_DIR/system_time_utc.txt"
w32tm /query /status > "$EVIDENCE_DIR/ntp_status.txt"  # Windows
ntpq -p > "$EVIDENCE_DIR/ntp_status.txt"  # Linux

# Environment variables
set > "$EVIDENCE_DIR/environment_vars.txt"  # Windows
env > "$EVIDENCE_DIR/environment_vars.txt"  # Linux

# Scheduled tasks / Cron jobs
schtasks /query /fo CSV /v > "$EVIDENCE_DIR/scheduled_tasks.csv"  # Windows
crontab -l > "$EVIDENCE_DIR/crontab_current.txt" 2>/dev/null  # Linux
ls -la /etc/cron.* > "$EVIDENCE_DIR/cron_dirs.txt" 2>/dev/null

# Services
sc queryex type=service state=all > "$EVIDENCE_DIR/services_all.txt"  # Windows
systemctl list-units --type=service --all > "$EVIDENCE_DIR/systemd_services.txt"  # Linux

# Windows Registry - key autostart locations
reg export "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" "$EVIDENCE_DIR/reg_run_hklm.reg" /y
reg export "HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Run" "$EVIDENCE_DIR/reg_run_hkcu.reg" /y
reg export "HKLM\SYSTEM\CurrentControlSet\Services" "$EVIDENCE_DIR/reg_services.reg" /y

Step 7: Hash All Evidence and Document Chain of Custody

# Generate SHA256 hashes for all collected evidence
cd "$EVIDENCE_DIR"
sha256sum * > evidence_manifest.sha256

# Create chain of custody record
cat > "$EVIDENCE_DIR/chain_of_custody.txt" << EOF
CHAIN OF CUSTODY RECORD
========================
Case ID: IR-YYYY-NNN
Collection Date: $(date -u)
Collected By: $(whoami)
System: $(hostname)
System IP: $(hostname -I 2>/dev/null || ipconfig | grep IPv4)
Collection Method: Live forensic collection via trusted USB toolkit

Evidence Items:
$(ls -la "$EVIDENCE_DIR/" | grep -v chain_of_custody)

SHA256 Manifest: evidence_manifest.sha256
Transfer: [TO BE COMPLETED]
Storage Location: [TO BE COMPLETED]
EOF

Key Concepts

Concept	Description
Order of Volatility	RFC 3227 - Collect most volatile data first: registers > cache > memory > disk
Live Forensics	Collecting evidence from a running system before shutdown
Chain of Custody	Documentation tracking evidence handling from collection to court
Forensic Soundness	Ensuring evidence collection doesn't alter the original evidence
Trusted Tools	Using verified tools from external media, not from the compromised system
Evidence Integrity	SHA256 hashing of all evidence immediately after collection
Locard's Exchange Principle	Every contact leaves a trace - minimize investigator artifacts

Tools & Systems

Tool	Purpose
WinPmem	Windows memory acquisition
LiME (Linux Memory Extractor)	Linux kernel memory acquisition
Sysinternals Suite	Process, handle, and DLL analysis (Windows)
Velociraptor	Remote forensic collection at scale
KAPE (Kroll Artifact Parser)	Automated artifact collection on Windows
CyLR	Cross-platform live response collection
GRR Rapid Response	Remote live forensics framework

Common Scenarios

1. Fileless Malware Attack: PowerShell-based attack with no files on disk. Memory dump is critical evidence containing the malicious scripts.
2. Active C2 Session: Attacker has live connection. Network connections and process data reveal C2 infrastructure.
3. Insider Data Theft: Employee copying files. Process list, mapped drives, and network connections show exfiltration activity.
4. Compromised Web Server: Web shell detected. Memory may contain additional backdoors not yet written to disk.
5. Lateral Movement in Progress: Attacker moving between systems. Authentication tokens and network sessions in memory reveal scope.

Output Format

• Memory dump file (.raw or .lime format) with SHA256 hash
• Network state captures (connections, ARP, DNS, routes)
• Process listings with command lines and parent processes
• User session and authentication data
• System configuration snapshots
• Evidence manifest with SHA256 checksums
• Chain of custody documentation