How does CSRF lead to Account Takeover? Real-world example and exploit chain explained

Table of Contents

• Why CSRF is Still Dangerous in 2025
• Real-World Example: CSRF to Account Takeover Chain
• Tools Used in CSRF Detection
• Real Case: $2,000 Bug Bounty for CSRF-Based Account Takeover
• Best Practices to Prevent CSRF
• When CSRF Becomes Dangerous: Chaining with Other Bugs
• CSRF in Mobile and API Security
• Common Mistakes That Lead to CSRF
• CSRF Attack Flow Summary
• Conclusion
• Frequently Asked Questions (FAQs)

Cross-Site Request Forgery (CSRF) is a vulnerability where an attacker tricks a logged-in user into performing unwanted actions on a web application. When chained with other weak security practices like poor token validation or session mismanagement, CSRF can result in full account takeover.

For example, if a banking application allows users to update their email without verifying the request origin or without proper CSRF token validation, an attacker could craft a malicious link that changes the victim’s email address to one the attacker controls. With that change, the attacker could initiate a password reset and gain full access.

Why CSRF is Still Dangerous in 2025

Despite improved frameworks and CSP headers, many web applications still rely on insecure patterns:

• Missing or predictable CSRF tokens

• GET requests performing state changes

• Lack of re-authentication before sensitive changes

• No origin or referer validation

These mistakes continue to make CSRF one of the most exploited bugs reported on platforms like HackerOne and Bugcrowd.

Real-World Example: CSRF to Account Takeover Chain

Vulnerable Application Flow:

1. A user logs into a vulnerable web app.

2. The “Update Email” endpoint accepts a POST request but does not verify a CSRF token.

3. The email change is accepted instantly without password confirmation.

4. The attacker sends the victim a CSRF payload embedded in an image or hidden form.

5. Once the user visits the attacker’s page, the request is made silently.

6. The attacker changes the email to [email protected].

7. The attacker uses "Forgot Password" with their email and takes over the account.

Exploit Payload (HTML):

Tools Used in CSRF Detection

Real Case: $2,000 Bug Bounty for CSRF-Based Account Takeover

A researcher found a CSRF vulnerability in an e-commerce site where the profile update endpoint lacked both CSRF token validation and origin checks. The victim's profile was modified to use the attacker’s email, leading to account takeover after a password reset. The platform rewarded $2,000 due to the severity and ease of exploitation.

Best Practices to Prevent CSRF

• Use anti-CSRF tokens (synchronizer tokens)

• Confirm actions with re-authentication

• Use the SameSite=Strict cookie flag

• Reject state-changing GET requests

• Validate the Origin and Referer headers

When CSRF Becomes Dangerous: Chaining with Other Bugs

• CSRF + Insecure Direct Object Reference (IDOR): Modify user IDs to change another user’s data.

• CSRF + Open Redirect: Redirect victim to phishing sites after CSRF action.

• CSRF + XSS: Execute malicious scripts post-CSRF form submission.

CSRF in Mobile and API Security

Many modern applications rely on APIs and mobile apps. If these endpoints do not implement CSRF protection or verify headers properly, the same CSRF vulnerability can apply via mobile browsers or embedded views.

APIs should use:

• OAuth scopes properly

• CSRF tokens for session-based authentication

• JWT-based mechanisms with care

Common Mistakes That Lead to CSRF

CSRF Attack Flow Summary

Conclusion

CSRF is not just a theoretical attack—it remains a real and dangerous threat, especially when combined with other vulnerabilities like weak token validation and insecure endpoint logic. The real-world chain of CSRF to account takeover shows how a small oversight can lead to severe security breaches.

If you're a beginner or intermediate bug bounty hunter, learning how to exploit these chains responsibly not only helps organizations patch critical flaws but also earns you valuable rewards.

FAQs

What is CSRF and how does it work?

CSRF (Cross-Site Request Forgery) tricks a user into submitting a malicious request, typically through their browser, without their consent or awareness.

How can CSRF lead to account takeover?

If an application doesn’t validate CSRF tokens properly, an attacker can change a user’s email, password, or settings, leading to account compromise.

What is a CSRF exploit chain?

A CSRF exploit chain combines multiple weak points (e.g., missing token + poor session handling) to perform a more severe attack like account takeover.

What are signs of CSRF vulnerability in a web app?

If sensitive operations (like password changes) don’t use CSRF tokens or allow requests from other domains, the app is likely vulnerable.

What makes CSRF so dangerous?

It takes advantage of user trust and browser cookies to perform unauthorized actions, often without alerting the victim.

What is a real-world CSRF example?

A common example includes auto-changing user email/password through hidden form submission in an authenticated session.

Can CSRF bypass 2FA?

Not directly, but if the 2FA reset mechanism is vulnerable, CSRF could help an attacker reconfigure or disable 2FA.

How do weak tokens lead to CSRF attacks?

If tokens are predictable, not session-bound, or not validated, attackers can forge them and submit unauthorized requests.

Can CSRF affect mobile apps?

Yes, if mobile APIs don’t properly validate tokens or restrict origin headers, CSRF can be exploited even on mobile endpoints.

Is CSRF still relevant in 2025?

Yes. Despite modern frameworks including defenses, misconfigurations, token misuse, or legacy systems keep CSRF relevant.

How can I test for CSRF vulnerabilities?

Use tools like Burp Suite, manually submit requests from unauthorized origins, or check if forms are missing tokens.

What is anti-CSRF token?

It’s a unique value attached to forms/requests that helps servers validate if the request is coming from an authorized source.

What are common CSRF protection mechanisms?

CSRF tokens, SameSite cookies, origin/referrer header validation, and user re-authentication.

How to fix CSRF vulnerabilities?

Use strong, session-based CSRF tokens, set SameSite cookie attributes, and validate origin/referrer headers.

Can CSRF work without user interaction?

Yes, using auto-submitting forms or malicious scripts embedded in emails or forums.

How does CSRF affect API endpoints?

APIs without token validation or CORS restrictions can be exploited if cookies are included in cross-origin requests.

What’s the difference between CSRF and XSS?

XSS executes scripts in the browser, while CSRF forces users to send unauthorized requests via their browser.

What’s the role of SameSite cookies in CSRF?

SameSite cookies restrict cookies from being sent on cross-site requests, reducing CSRF risk.

Can attackers steal sessions with CSRF?

No, CSRF exploits the victim’s session; it doesn't steal it. But it can change settings or actions within that session.

Are JSON APIs vulnerable to CSRF?

Less likely, but not immune. Especially if requests are not restricted by CORS and tokens are missing.

What is the cost of a real-world CSRF bug bounty?

Depending on impact, payouts range from $250 to over $5,000. Account takeover bugs usually receive higher rewards.

How to chain CSRF with other bugs?

You can chain CSRF with IDOR, token reuse, or privilege escalation to maximize the attack’s impact.

Is CSRF detectable by automated scanners?

Partially. Some scanners detect missing tokens but cannot assess business logic flaws exploited by CSRF.

Can you use Burp Suite for CSRF?

Yes. Burp Suite is commonly used to test, craft, and replay CSRF payloads in web applications.

What is CSRF token reuse?

If tokens don’t expire or are not unique per request/session, an attacker can reuse captured tokens for malicious actions.

How to exploit CSRF in password reset flows?

If the reset form lacks a token or weakly validates it, you can submit a crafted form to change a user’s password.

Why are banking apps vulnerable to CSRF?

If session cookies are not scoped properly and CSRF protection is not implemented on sensitive endpoints.

Can CAPTCHA prevent CSRF?

Not effectively. CAPTCHA helps against bots, but doesn’t protect against CSRF unless paired with token validation.

What is a CSRF PoC (Proof of Concept)?

A crafted HTML form or script that auto-submits malicious requests on behalf of a logged-in user.

Are REST APIs vulnerable to CSRF?

Yes, if they rely on cookies for authentication and do not implement CSRF mitigations.