Post

Access control - PortSwigger

Posted
By karim moftah
5 min read
Access control - PortSwigger


Table of Contents



Unprotected admin functionality

Goal : delete the user carlos by accessing the admin panel

  • go to /robots.txt , you will find the admin panel path

  • 1
2

    User-agent: *
Disallow: /administrator-panel
  • go to /administrator-panel and delete carlos



Unprotected admin functionality with unpredictable URL

Goal : delete the user carlos by accessing the admin panel

  • view the page source , you will find this javascript code
1
2
3
4
5
6
7
8
9
10
11

var isAdmin = false;
if (isAdmin) {
   var topLinksTag = document.getElementsByClassName("top-links")[0];
   var adminPanelTag = document.createElement('a');
   adminPanelTag.setAttribute('href', '/admin-h49xc1');
   adminPanelTag.innerText = 'Admin panel';
   topLinksTag.append(adminPanelTag);
   var pTag = document.createElement('p');
   pTag.innerText = '|';
   topLinksTag.appendChild(pTag);
}
  • go to the admin panel /admin-h49xc1 and delete carlos



User role controlled by request parameter

Goal : delete the user carlos by accessing the admin panel

  • go to /login , login with your credentials wiener : peter
  • modify Admin in the cookies from false to true
  • go to /admin and delete carlos



User role can be modified in user profile

Goal : delete the user carlos by accessing the admin panel

  • go to /login , login with your credentials wiener : peter
  • update your email , you will find that your account info are exist in the response


  • send the request to burp repeater and add "roleid" : 2 to the request


  • go to /admin and delete carlos



User ID controlled by request parameter

Goal : obtain the API key for the user carlos and submit it as the solution.

  • go to /login , login with your credentials wiener : peter
  • click My account , notice that id parameter is ?id=wiener
  • change wiener to carlos


access control



User ID controlled by request parameter, with unpredictable user IDs

Goal : find the GUID for carlos, then submit his API key as the solution.

  • go to /login , login with your credentials wiener : peter
  • click My account , notice that id parameter
1

/my-account?id=9afc9f90-2dc9-443d-b6e4-2bd1b5c6a2a5
  • return to home page ,open any post that carlos posted and get his GUID from the url
  • go to my-account and change your GUID with carlos ‘s GUID

access control



User ID controlled by request parameter with data leakage in redirect

Goal : obtain the API key for the user carlos and submit it as the solution.

  • go to /login , login with your credentials wiener : peter
  • click My account , notice that id parameter
  • change value of id to carlos , you will be redirected to the login page but carlos’s information will be exposed in the response

access control



User ID controlled by request parameter with password disclosure

Goal : retrieve the administrator’s password, then use it to delete carlos.

  • go to /login , login with your credentials wiener : peter
  • click My account , notice that id parameter
  • change id to administrator , change type in the input from password to text to see the password in clear text


  • login with administrator account ,go to admin panel and delete carlos’s account



Insecure direct object references

Goal : find the password for the user carlos, and log into their account.

  • go to Live chat and send any message

  • click view transcript to download a txt file with your chat

  • view it in burp and you will see that it send GET to /download-transcript/2.txt

    1

    GET /download-transcript/2.txt HTTP/1.1

  • send the request to burp repeater and change 2.txt to 1.txt to see carlos ‘s chat


  • login with carlos account



Method-based access control can be circumvented

Goal : exploit the flawed access controls to promote yourself to become an administrator.

  • go to /login , login with your admin credentials administrator:admin.
  • go to the admin panel and downgrade wiener , send the request to burp repeater


  • logout and login with your credentials wiener : peter
  • from burp repeater change the method from POST to GET



  • add username parameter and the action to the request



Multi-step process with no access control on one step

Goal : log in using the credentials wiener:peter and exploit the flawed access controls to promote yourself to become an administrator.

  • go to /login , login with your admin credentials administrator:admin.
  • go to the admin panel and upgrade carlos to admin , and confirm then logout
  • notice the requests and responses from burp history
  • login with your credentials wiener : peter.
  • send the request to burp repeater
  • if you try to upgrade your account , you will get 401 Unauthorized , so this step requires admin privileges


  • however if you send the confirmation request , you will get 200 OK , so this step has flawed access control and you are an admin



Referer-based access control

Goal : log in using the credentials wiener:peter and exploit the flawed access controls to promote yourself to become an administrator.

  • go to /login , login with your admin credentials administrator:admin.
  • go to the admin panel and upgrade carlos to admin , and logout
  • notice the requests and responses from burp history
  • login with your credentials wiener : peter
  • send the request to burp repeater
  • try to send request after changing username to wiener , you will get 401 because the referer header is required
  • copy the referer header from pervious request when you logged in as an administrator
  • send the request and you will be an admin



PortSwigger
PortSwigger writeup penetration testing Access control
This post is licensed under CC BY 4.0 by the author.