Meta fixes bug that can bypass Facebook 2FA

Meta has fixed a Facebook vulnerability that could have allowed an attacker to bypass SMS-based two-factor authentication (2FA). The bug, which earned its discoverer a $27,200 bounty, accomplished this by confirming the targeted user’s already-verified Facebook mobile number via Instagram’s Meta Accounts Center.

Gtm Mänôz, the researcher, discovered that a user could link their Instagram and Facebook accounts by entering an already proven mobile number associated with the Facebook account. After entering the user’s mobile number, Facebook generates a one-time code to verify the user’s identity.

Users could add their email and phone number to both their Instagram and linked Facebook accounts, which could then be verified via a six-digit code sent via email or SMS. Any random six digits can, however, be entered and the request intercepted using a web proxy such as Burp Suite.

The issue on Instagram’s endpoint, on the other hand, could enable a threat actor to push infinite bot traffic to introduce a brute-force attack to verify a one-time Facebook PIN to link the accounts, successfully circumventing Facebook’s 2FA protections.

When the attacker correctly entered the code, the victim’s phone number was linked to the attacker’s Facebook account. A successful attack would still result in Meta sending a message to the victim stating that their two-factor authentication had been disabled because their phone number had been linked to someone else’s account.

The sources for this piece include an article in TechCrunch.

IT World Canada Staff
IT World Canada Staff
The online resource for Canadian Information Technology professionals.

Would you recommend this article?


Thanks for taking the time to let us know what you think of this article!
We'd love to hear your opinion about this or any other story you read in our publication.

Jim Love, Chief Content Officer, IT World Canada

Featured Download

ITW in your inbox

Our experienced team of journalists and bloggers bring you engaging in-depth interviews, videos and content targeted to IT professionals and line-of-business executives.

More Best of The Web