Ever thought a tiny tweak in a URL or cookie could make you the admin of a website?

Sounds unbelievable? Let’s dive into Broken Access Control — one of the most critical web vulnerabilities.

🔍 What is Broken Access Control?

Broken Access Control occurs when a web application fails to properly enforce what authenticated users are allowed to do.

For example, you might log in as a normal user but, due to poor security checks, you could change your role to an admin just by manipulating URLs, cookies, or request parameters. This often leads to data exposure, unauthorized actions, or even a complete compromise of the system.

🧪 Learning via PortSwigger Labs

PortSwigger Labs is a hands-on playground for anyone who wants to learn how web vulnerabilities work in real-world scenarios. I practiced a Broken Access Control lab where the attack vector was based on user role manipulation and cookie tampering.

🛠️ Steps I Followed in the Lab:

1. Login with the provided credentials

I used the given test account: username: wiener password: peter

2. Observing the URL

After logging in, I noticed the account page had a query parameter:

https://example.com/my-account?id=wiener
        

Thought experiment: What happens if I change wiener to administrator?

I replaced it with:

https://example.com/my-account?id=administrator
        

The page behaved differently, hinting at ID-based access control flaws.

3. Intercepting with BurpSuite

To dive deeper, I turned on BurpSuite Intercept and captured the HTTP request.

Inside the cookies, I found something interesting:

admin=false  
session=abcd1234
        

This cookie flag (admin=false) was clearly deciding user privileges.

4. Privilege Escalation

I simply edited the cookie value:

admin=true
        

Then, I forwarded the request. Result? I suddenly had admin-level access — I could even see the user that was meant to be deleted!

⚠️ What does this tell us?

This demonstrates a serious security flaw:

• If user roles (like admin privileges) are determined client-side (via cookies or query parameters), attackers can manipulate them.
• Without server-side validation, attackers can gain unauthorized access, delete accounts, or retrieve sensitive data.

🔑 Key Security Lessons:

1. Never trust user input or cookies — all access control decisions must happen on the server-side.
2. Use role-based access checks at every endpoint.
3. Implement secure cookies with flags like HttpOnly and Secure.
4. Monitor and log abnormal access patterns for early detection of such attacks.

💬 My Takeaway

This lab made me realize how simple oversights (like trusting a query parameter or cookie value) can lead to complete system compromise. It’s not always about fancy exploits — sometimes, the smallest tweaks can open the biggest doors.

#CyberSecurity #BrokenAccessControl #WebSecurity #EthicalHacking #PortSwiggerLabs #BugBounty