Account Takeover


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:, X-Forwarded-Host:
  3. Forward the request with the modified header
    POST HTTP/1.1
    Accept: */*
    Content-Type: application/json
  4. Look for a password reset URL based on the host header like :

Password Reset Via Email Parameter

# parameter pollution

# array of emails

# carbon copy

# separator,|

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
    POST /api/changepass
    ("form": {"email":"","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:
  2. Inspect the server response and check for resetToken
  3. Then use the token in an URL like[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

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 : *
  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)
    git clone
    cd smuggler
    python3 -h
  2. Craft a request which will overwrite the POST / HTTP/1.1 with the following data:
    GET  HTTP/1.1
  3. Final request could look like the following
    GET /  HTTP/1.1
    Transfer-Encoding: chunked
    User-Agent: Smuggler/v1.0
    Content-Length: 83
    GET  HTTP/1.1
    X: X

Hackerone reports exploiting this bug

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


  • Broken cryptography
  • Session hijacking
  • OAuth misconfiguration