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Why You Shouldn’t Use Texts For Two-Factor Authentication

An anonymous reader quotes a report from The Verge: A demonstration video posted by Positive Technologies (and first reported by Forbes) shows how easy it is to hack into a bitcoin wallet by intercepting text messages in transit. The group targeted a Coinbase account protected by two-factor authentication, which was registered to a Gmail account also protected by two-factor. By exploiting known flaws in the cell network, the group was able to intercept all text messages sent to the number for a set period of time. That was enough to reset the password to the Gmail account and then take control of the Coinbase wallet. All the group needed was the name, surname and phone number of the targeted Bitcoin user. These were security researchers rather than criminals, so they didn’t actually steal anyone’s bitcoin, although that would have been an easy step to take. At a glance, this looks like a Coinbase vulnerability, but the real weakness is in the cellular system itself. Positive Technologies was able to hijack the text messages using its own research tool, which exploits weaknesses in the cellular network to intercept text messages in transit. Known as the SS7 network, that network is shared by every telecom to manage calls and texts between phone numbers. There are a number of known SS7 vulnerabilities, and while access to the SS7 network is theoretically restricted to telecom companies, hijacking services are frequently available on criminal marketplaces. The report notes of several ways you can protect yourself from this sort of attack: “On some services, you can revoke the option for SMS two-factor and account recovery entirely, which you should do as soon as you’ve got a more secure app-based method established. Google, for instance, will let you manage two-factor and account recovery here and here; just set up Authenticator or a recovery code, then go to the SMS option for each and click ‘Remove Phone.'”

Read more of this story at Slashdot.

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