FirstBlood-#214Can change email when modifying an appointment

On 2021-05-12, rintox reported:


The application does not let you change your email when you already create an appointment. This logic can by bypassed by adding the parameter email and a new cookie to the /api/ma.php request.

Steps to reproduce

  1. Go to /manageappointment.php?aptid=<ID> and read the source code
  2. Notice there's a comment with the variable email. Apparently, the xhr request when modifying the appointment just needs the message and id parameters.

  1. Add the email parameter when modifying the appointment and refresh the page to see if the email value has changed.

  1. As you can notice, the email value hasn't changed. Something else is missing...
  2. Go to /register.php endpoint, fill the input fields with whatever information and notice the server response assigns a new cookie. doctorAuthed=eyJkb2N0b3JBdXRoIjphdXRoZWR9

  1. Add this new cookie to the previous request (ma.php with a new email value)

  1. Refresh your /manageappointment.php?aptid=<ID> endpoint and notice the email value has changed


The /api/ma.php is vulnerable to and IDOR vulnerability ( ) and this logic error. When combined, a hacker can change the message and email of all appointments.

P2 High

Endpoint: /api/ma.php

Parameter: email

Payload: NA

FirstBlood ID: 7
Vulnerability Type: Application/Business Logic

The endpoint MA.php (to modify an appointment) only allows for certain values to be modified, however due to some application logic error, if the user has tried to signup as a doctor and has the cookie "doctorAuthed" set, then it allows them to modify the email address for any appointment.

Respect Earnt: 2000000
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