Security Experts:

SIM Swapping Blamed for Hacking of Twitter CEO's Account

Hackers were able to post offensive messages from the Twitter account of Jack Dorsey, the social media company’s CEO, after they tricked his mobile services provider into handing over his phone number.

The hackers who took control of Dorsey’s account used it to post racist and anti-Semitic messages and even bomb threats. The tweets were removed by Twitter after roughly half an hour.

The attack has been attributed to Chuckling Squad, a hacker group that in the past targeted other high-profile individuals, particularly social media influencers.

Following the incident, Twitter clarified that its systems had not been compromised. The company stated, “The phone number associated with the account was compromised due to a security oversight by the mobile provider. This allowed an unauthorized person to compose and send tweets via text message from the phone number. That issue is now resolved.”

The technique used by the hackers is called a SIM swap or port-out scam. In these attacks, the attacker uses social engineering to convince a mobile phone operator to transfer the targeted individual’s phone number to their own SIM card. This can be used to bypass SMS-based two-factor authentication (2FA), but in the attack targeting the Twitter CEO it served a different purpose.

It allowed the hackers to post messages to Dorsey’s account through Cloudhopper, a mobile messaging technology provider that Twitter acquired back in 2010. Cloudhopper allows users to tweet by sending their message via SMS to a specific number. Since the hackers gained control of Dorsey’s phone number, they could easily post messages to his account without actually having to log in.

It’s worth noting that SMS messages can be used to perform various tasks on Twitter, including following or unfollowing a specific user, turning notifications on or off, and retweeting messages.

SIM swapping appears to be the Chuckling Squad’s favorite method for hijacking social media accounts and they have often targeted AT&T.

“SIM swap scams have become a much more prominent and dangerous threat over the past year. It has been proven to be a shockingly easy way of subverting two-factor authentication by either successfully tricking carrier agents to move a user's phone number to a new SIM card or through bribing one of these agents,” Ryan Rowcliffe, Lead of Solutions Architecture at SecureAuth, told SecurityWeek.

“Since carriers are the real targets in this scenario, they have a responsibility to look for suspicious patterns running through their call centers and customer service organizations in order to find fraudulent activity or reps who have been bribed by cybercriminals,” Rowcliffe added.

“At the very least, consumers should contact their phone carriers and request for additional security to be applied to their accounts such as not allowing account changes without a verification code delivered over a non-sms channel,” he said. “As an industry we should be working with phone carriers to find alternative ways to confirm possession of the phone prior to allowing changes to an account of this nature.”

Related: Nine Charged in SIM Hijacking Scheme

Related: Attackers Circumvent Two Factor Authentication Protections to Hack Reddit

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.