API Vulnerability: Unnecessary HTTP Methods

By /

Listen to this Post

Featured Image
When testing API endpoints, one of the most basic yet critical vulnerabilities to check is whether unnecessary HTTP methods are enabled. If an endpoint only requires a `GET` request but allows PUT, POST, or DELETE, it could lead to unauthorized data manipulation or exploitation.

Why This Matters

APIs often handle sensitive data, and improper method configurations can expose them to:
– Data Tampering (e.g., modifying records via `PUT` when only `GET` should be allowed).
– Unauthorized Actions (e.g., deleting resources via DELETE).
– Information Disclosure (e.g., `OPTIONS` revealing excessive details).

How to Check for Unnecessary HTTP Methods

Using cURL

curl -X OPTIONS http://example.com/api/user -I

This checks which HTTP methods are allowed.

Using Nmap

nmap --script http-methods --script-args http-methods.url-path='/api/user' example.com

Using Burp Suite

1. Intercept a request to the API endpoint.

2. Send it to Repeater.

  1. Manually change the HTTP method (e.g., `GET` to PUT) and observe the response.

Automated Testing with OWASP ZAP

  1. Run an Active Scan on the target API.
  2. Check the Alerts tab for “HTTP Method Tampering” warnings.

Mitigation Steps

  1. Explicitly Allow Only Required Methods (e.g., in Apache):
    <Location "/api/user">
LimitExcept GET POST {
Deny from all
}
</Location>

2. Disable Unused Methods in Nginx:

location /api/user {
if ($request_method !~ ^(GET|POST)$ ) {
return 405;
}
}

3. Use Framework-Level Restrictions (e.g., in Flask):

from flask import Flask
app = Flask(<strong>name</strong>)

@app.route('/api/user', methods=['GET'])
def get_user():
return {"data": "user_info"}

You Should Know:

  • OPTIONS Method Disclosure: Can reveal internal API structures. Block it if not needed.
  • HEAD Method Abuse: Can bypass authentication in poorly configured systems.
  • TRACE Method Risks: Can lead to Cross-Site Tracing (XST) attacks.

Expected Output:

When testing `http://example.com/api/user`:

HTTP/1.1 200 OK 
Allow: GET, HEAD, OPTIONS

If `PUT` or `DELETE` is listed, the endpoint is misconfigured.

What Undercode Say:

APIs are the backbone of modern web apps, and misconfigured HTTP methods are low-hanging fruit for attackers. Always restrict methods to the bare minimum. Use automated scanners, but manual verification is key.

Prediction:

As APIs grow more complex, automated misconfiguration detection will become standard in CI/CD pipelines, reducing human error in method restrictions.

Expected Output:

A secure API should only respond to intended methods (e.g., `GET` for data retrieval) and reject unauthorized ones with 405 Method Not Allowed.

References:

Reported By: Activity 7325993458102337537 – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

Join Our Cyber World:

💬 Whatsapp | 💬 Telegram

Related Posts: