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How to complete the HTTP Method Override Challenges

All of the method override challenges use the same mechanism so we can cover them all in this solution.

Sometimes tools and libraries will not issue TRACE or PATCH requests. There is a specific HTTP header we can use to try and have POST requests treated as other verbs.

The header "X-HTTP-Method-Override" is not guaranteed to work on every server, but some HTTP servers will take this header and treat the request using the value in the header:

X-HTTP-Method-Override: DELETE

This is worth understanding because it might also be used to bypass validation, or trigger functionality that the user is not authorized to trigger.

POST /heartbeat

Issue a POST request to /heartbeat with an X-HTTP-Method-Override header specifying the verb you actually want

  • POST request can be sent by all tools
  • We need to add the header X-HTTP-Method-Override to the request and the value should be the verb we want to send e.g. TRACE

Basic Instructions

Each challenge requires a different verb, but the process is the same for each, the only difference is the value of the X-HTTP-Method-Override header

  • Issue a POST request to end point "/heartbeat"
  • The request should have an X-HTTP-Method-Override with the value associated with the challenge i.e. DELETE, PATCH, TRACE
  • The request should have an X-CHALLENGER header to track challenge completion
  • The response status code should match the value for teh challenge overridden verb
    • for DELETE be 405
    • for TRACE be 501
    • for PATCH be 500 as the API is simulating a server error

NOTE: This header feature is normally implemented by the HTTP server so often development teams are not even aware that this is possible. Depending on how requests are validated in code it might be possible for someone, who has amend access using POST but who does not have DELETE access, to be able to use this header approach to delete something.

NOTE: As an additional exercise, you might want to see if you can DELETE todos using a POST and the X-HTTP-Method-Override header. Experiment and see what you can achieve using this approach.

Example Request

> POST /todos/3 HTTP/1.1
> Host: apichallenges.eviltester.com
> User-Agent: rest-client
> X-HTTP-Method-Override: DELETE
> X-CHALLENGER: x-challenger-guid
> Content-Type: application/json
> Accept: */*
> Content-Length: 108

 

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