Twitter Bug Exposed Millions of User Phone Numbers

A bug in Twitter's Android app let users connect random phone numbers to real Twitter handles.

AccessTimeIconDec 26, 2019 at 9:00 p.m. UTC
Updated Sep 13, 2021 at 11:53 a.m. UTC
10 Years of Decentralizing the Future
May 29-31, 2024 - Austin, TexasThe biggest and most established global event for everything crypto, blockchain and Web3.Register Now

A security researcher was able to use a bug in the Twitter Android app to identify millions of Twitter users, connecting their phone numbers to their Twitter IDs. The exploit could expose failures in the company's two-factor authentication system and give other security developers pause.

According to a TechCrunch report, the researcher, Ibrahim Balic, created randomized lists of phone numbers and sent them to Twitter.

“If you upload your phone number, it fetches user data in return,” he said.

The user data allowed Balic to find phone numbers for many major Twitter "celebrities" including the private number of a "senior Israeli politician."

“Upon learning of this bug, we suspended the accounts used to inappropriately access people’s personal information. Protecting the privacy and safety of the people who use Twitter is our number one priority and we remain focused on rapidly stopping spam and abuse originating from use of Twitter’s APIs,” a Twitter spokesperson said.

The bug exposed user accounts when Balic uploaded millions of phone numbers and asked Twitter to match them with users. Typically this interface is used only when new users install the app on their phone but, using a set of API calls, Balic was able to spoof this behavior. The resulting breach of privacy - essentially connecting real numbers to real Twitter handles - could reduce the efficacy of two-factor authentication schemes popular on financial applications and wallets.

Image via Shutterstock.

Disclosure

Please note that our privacy policy, terms of use, cookies, and do not sell my personal information has been updated.

CoinDesk is an award-winning media outlet that covers the cryptocurrency industry. Its journalists abide by a strict set of editorial policies. In November 2023, CoinDesk was acquired by the Bullish group, owner of Bullish, a regulated, digital assets exchange. The Bullish group is majority-owned by Block.one; both companies have interests in a variety of blockchain and digital asset businesses and significant holdings of digital assets, including bitcoin. CoinDesk operates as an independent subsidiary with an editorial committee to protect journalistic independence. CoinDesk employees, including journalists, may receive options in the Bullish group as part of their compensation.


Learn more about Consensus 2024, CoinDesk's longest-running and most influential event that brings together all sides of crypto, blockchain and Web3. Head to consensus.coindesk.com to register and buy your pass now.