BUG POC -> Pre-Authentication Account Takeover

BUG POC -> Pre-Authentication Account Takeover

Hello hackers,

we are again back to our duty and something new…

Today we are going to learn about a BUG and analyze its POC (Proof Of Concept)

A few days back I was working on a private bug bounty program in that program, I have found this BUG,…It was a private program so I cannot disclose its name, let’s take this as an “example.com”.

Vulnerability name : Pre-Authentication Account Takeover

Severity : High

Vulnerable URL : https://www.example.com/signin

This vulnerability implies or says that there is no proper email validation via the sign-up page which leads an attacker to take over an Account.


  • Attacker step–>Go to example.com sign-up page and register a new account using victim email. I have noticed that it has a google authentication option so, I used the Gmail account email address of the victim to register an account.
  • Make sure that you have successfully logged in as a user upon the registration process completed.
  • Now, you have to log out from there and navigate yourself to the sign-in page.
  • Victim step–>This time victim will log in using Google authentication using the same email used in step-1
  • After login, the victim can access the application and make a change to anywhere in the profile and update it…
  • Attacker step–>Now in a separate  browser attacker will log in to the account using an email id and password used in step 1
  • Once you have logged in , if you are able to see the updated profile which has been done by the victim. It is considered a full account take over vulnerability.


  • It allows an attacker to keep persistent access to the victim account, till the password is not changed manually by the victim…
  • There is no proper email validation via signup, this allows an attacker to gain access to a full account.
  • Due to lack of email validation coming from social login and even it’s failed to check the account already exists…

I hope after reading this you, even start finding this vulnerability on websites,…

Its done for today now its time to say GOOD BYE for now

Happy Hacking!!

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