Authy Users Urged to Stay Alert After 33 Million Phone Numbers Exposed

Twilio has updated its Authy two-factor authentication (2FA) service after a hacker claimed to have retrieved 33 million phone numbers from its user database.

TechCrunch reports that the hacker(s) known as ShinyHunters took to a well-known hacking forum to boast about the theft of 33 million cell phone numbers, achieved by what Twilio described as the use of an "authenticated endpoint."

The U.S. messaging giant confirmed this week that "threat actors" gained access to its servers, resulting in the theft of users' phone numbers, but it did not specify how many were accessed. The company said it had taken action to secure the exploit and prevent similar future unauthenticated requests.

"We have seen no evidence that the threat actors obtained access to Twilio's systems or other sensitive data," said the company in a blog post. "While Authy accounts are not compromised, threat actors may try to use the phone number associated with Authy accounts for phishing and smishing attacks; we encourage all Authy users to stay diligent and have heightened awareness around the texts they are receiving."

As Twilio notes, obtaining a list of phone numbers may not appear in itself to pose a severe security threat. However, attackers could conceivably contact users and claim to be Authy or Twilio representatives in order to get them to reveal personal information as part of a phishing campaign.

Users should update to the latest version of the iOS app, available on the App Store. Twilio also advises users who cannot access their Authy account to contact its support team immediately.

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At the beginning of the year, Authy announced that it was shutting down its Mac and Linux desktop apps in August 2024, but ended up bringing the date forward. The apps were subsequently killed off in March.