How to Chain Multiple Vulnerabilities for Maximum Impact in Bug Bounty Hunting

Introduction

Bug bounty hunting is often about finding a single vulnerability that could lead to security risks. However, the real game-changers—the kind that fetch high rewards—are when you chain multiple vulnerabilities together to achieve a more severe impact.

In this blog, we’ll dive deep into chaining vulnerabilities, why it's powerful, and how you can do it to escalate low-severity issues into critical findings.

Why Vulnerability Chaining Matters

Most security issues found in bug bounties aren’t standalone critical vulnerabilities. Often, they are minor flaws that don’t seem impactful at first glance. However, when combined, they can bypass security controls, escalate privileges, or result in full compromise.

For example, an XSS (Cross-Site Scripting) vulnerability on its own might only allow JavaScript execution. But if you chain it with a CSRF (Cross-Site Request Forgery) flaw, you could potentially perform privileged actions on behalf of an admin—leading to account takeover.

Types of Vulnerability Chains That Work

Here are some common ways bug hunters successfully chain vulnerabilities:

1️⃣ XSS + CSRF = Admin Account Takeover

• XSS (Cross-Site Scripting): Allows an attacker to execute JavaScript in a victim's browser.

• CSRF (Cross-Site Request Forgery): Triggers unauthorised actions on behalf of an authenticated user.

  
  

Impact:If an XSS vulnerability allows an attacker to inject malicious scripts, they can use CSRF to perform actions like changing passwords or adding new admin accounts, leading to full system compromise.

💡 Example: Injecting a malicious script that auto-submits a hidden form, changing the admin’s email, and taking over the account.

2️⃣ SSRF + RCE = Server Takeover

• SSRF (Server-Side Request Forgery): Allows an attacker to send requests from the server.

• RCE (Remote Code Execution): Allows an attacker to execute code on the server.

  
  

Impact:An SSRF vulnerability alone may let an attacker access internal services. However, if they can find an internal endpoint vulnerable to RCE, they can exploit it to gain full control over the server.

💡 Example:

1. SSRF is used to access an internal admin panel (http://localhost/admin).

2. The admin panel has a file upload feature vulnerable to RCE.

3. The attacker uploads a malicious web shell, leading to complete server takeover.

   
   

3️⃣ IDOR + API Misconfiguration = Data Breach

• IDOR (Insecure Direct Object Reference): Allows access to unauthorised data by modifying object IDs.

• API Misconfiguration: Weak API controls that expose sensitive data.

  
  

Impact:A simple IDOR vulnerability might allow an attacker to change a user ID and view another user’s details. But if the API is misconfigured, they might be able to enumerate all user records, leading to a massive data breach.

💡 Example:

1. The attacker modifies GET /api/user/1234 to GET /api/user/1235 and sees another user’s data.

2. If API rate-limiting is weak, they can brute-force millions of user IDs and extract all user records.

   
   

4️⃣ Open Redirect + OAuth Misconfiguration = Account Hijack

• Open Redirect: Redirects users to untrusted sites without validation.

• OAuth Misconfiguration: Weak authentication flows in OAuth-based login systems.

  
  

Impact:A malicious attacker can use an open redirect to send users to a fake OAuth login page. If the OAuth implementation is weak, they can steal OAuth access tokens, leading to account hijacking.

💡 Example:

A user clicks on a link like:bashCopyEdithttps://legit-site.com/login?redirect=http://evil.com

1. 
   

2. They are redirected to a phishing page mimicking the real login.

3. The attacker captures the victim’s OAuth token and gains full access to their account.

How to Think Like a Hacker (Mindset for Chaining Bugs)

To chain vulnerabilities successfully, you need to think beyond single weaknesses and consider the bigger picture:

✅ Ask yourself:

• “What happens if I combine this bug with another issue?”

• “Does this low-severity bug become high-severity when used differently?”

• “Can I use this vulnerability to pivot deeper into the system?”

✅ Look for Patterns:

• Low-risk vulnerabilities (e.g., IDOR, XSS, Open Redirects) often become critical when chained.

• Focus on misconfigurations, as they frequently lead to privilege escalation.

✅ Try Automation:

• Use Burp Suite’s Intruder or custom Python scripts to automate API enumeration.

• Combine automated scanning with manual testing to uncover hidden attack chains.

  
  

Real-World Case Study

Bug Bounty Hunter Earns $15,000 by Chaining Vulnerabilities

A researcher found a CSRF vulnerability that allowed changing user emails but wasn’t exploitable alone because it required authentication.

🔗 How they escalated it:

1. They found an XSS vulnerability on the same domain.

2. The XSS payload triggered a CSRF request to change the admin’s email.

3. They reset the admin password using the new email.

4. Account Takeover Achieved → Critical Bug Reported!

💰 Bug Bounty Reward: $15,000

👉 Lesson Learned: Never ignore "low-impact" bugs—they could be goldmines when combined!