Insecure Data Manipulation via HTTP GET Requests

One common mistake developers make is using the HTTP GET method to send data that should only be posted using the POST method. This mistake can lead to data manipulation, making your application vulnerable to attacks. Let’s break this down and see why it happens and how to fix it.




VULNERABILITY

The problem arises when GET is used to send data that changes something on the server, like updating user information or deleting records. Since GET requests include data in the URL, this can expose sensitive information and allow bad actors to manipulate data.

IMPACT

This vulnerability occurs because developers may mistakenly use GET requests for actions that should only be handled by POST requests. Here’s why this is dangerous:

Navigating the Web Application Security Landscape

Data in the URL:

With GET, all data is sent as part of the URL, visible to anyone who can see it. This means sensitive data (like user IDs or passwords) can be exposed.

Caching Issues:

GET requests are often saved in the browser's cache, meaning someone else could access them and potentially misuse the data.

Cross-Site Request Forgery (CSRF):

Malicious users can trick other users into clicking on a harmful link, causing unwanted changes on the server without the user’s consent.

Bookmarking and Sharing:

Users might accidentally bookmark or share URLs that contain sensitive data in GET requests, exposing it to others.

SOLUTION

1. Use POST for Data-Altering Actions

Always use POST (or PUT/DELETE where needed) for operations that change data on the server. Unlike GET, POST keeps data hidden and safe.

For example, use a form like this for updating user data:
< form action="/update-user" method="POST">
< input type="text" name="newName" value="John Doe">
< input type="hidden" name="userId" value="123">
< button type="submit">Update

2. Add CSRF Protection

Protect your app from malicious requests by using a CSRF token. This unique code makes sure the request is coming from a trusted source.

# Example in Flask
@app.route('/update-user', methods=['POST'])
def update_user():
csrf_token = request.form['csrf_token']
if not validate_csrf(csrf_token):
return "CSRF token invalid", 403
# Continue with the update

3. Validate Inputs

Always check and clean any data coming from users to prevent harmful input. Use secure libraries that automatically handle this for you.

4. Encrypt Data with HTTPS

Use HTTPS (instead of HTTP) to encrypt all communication between the user’s browser and your server, making it harder for hackers to intercept the data.

5. Regular Security Audits

Regularly check your code to make sure you’re not using GET for actions that change data.

Author Avatar

Radhika Lad

Cyber Security Analyst

Location: Pune, India

Radhika is a web and network Pentester and ethusiast in cyber security domain. Her primary focus is on Vulnerability Assessment and Penetration testing of corporate networks, firewalls, web and cloud apps, mobile apps. Coming from finance and education background, she has a passion to get into the world of IoT and OT Cyber security. She is always on the path of learning and trying new things in the domain she likes.