Short Bytes: A white hat hacker from California has shown how easily he could’ve exploited Facebook’s password reset mechanism to hack numerous Facebook accounts. He even hacked the account of a random Facebook user by collecting 2 million valid Facebook IDs and requesting their password reset codes in a short period of time. Then, he picked a random code and brute-forced all accounts in his database.
Once such account was recently published by security researcher Gurkirat Singh. In a blog post, he wrote about a security loophole in Facebook’s password reset mechanism that could have given him a complete access to the target’s Facebook account. By doing so, he could’ve viewed many users’ all private messages, view card details, or anything else.
Facebook’s password reset bug — Explained
Explaining the bug, he tells how Facebook allows you to reset your Facebook password. The social networking website makes use of an algorithm to generate a random 6-digit passcode i.e. 10⁶ = 1,000,000 possible combinations. Interestingly, this code doesn’t change (if requested from mbasic.facebook.com) until it gets used.
So, if 1 million people request a password reset within a short period of time and no one uses the reset code, then 1,00,0001th person to request code will get a previously assigned number.
How to hack Facebook accounts by exploiting password reset bug?
To hack Facebook accounts and prove his point, Gurkirat collected 2 million valid Facebook IDs. He did so by making queries to Facebook’s Graph API starting with 100,000,000,000,000. This way, he easily got profile picture and full name of 2 million users.
Then, Gurkirat used a script to initiate the password reset request for those 2 million users. This process consumed the complete 6-digit range. In order to avoid getting his IP blocked from repeatedly sending password reset requests, he used a proxy server that assigned random IP addresses to each HTTP request.
Here’s the huge amount of preparation done by him to run his script:
The next step involved picking up a random 6 digit password and brute forcing all the users in list database. In his words — “And guess what? I was able to find a matching ID.” Thus, he was able to get the complete access to a random user’s Facebook account.
Facebook has patched this bug after Gurkirat’s report and award him just $500 bounty. Gurkirat writes that despite being a critical bug, Facebook labeled his finding as low priority.
Here’s what Gurkirat has to say:
Important: Please note that this article is only for educational purposes.
You can read Gurkirat’s complete account here.
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Also Read: Story of Chris Putnam: The First Facebook Hacker