1,900 Signal users exposed following Twilio breach

Posted on


The attacker behind the current Twilio information breach could have accessed the cellphone numbers and SMS registration codes of 1,900 customers of the favored safe messaging app Sign.

“Among the many 1,900 cellphone numbers, the attacker explicitly searched for 3 numbers and we obtained a report from a kind of three customers that their account was re-registered,” the Sign staff shared Monday.

What occurred?

Twilio gives cellphone quantity verification companies (through SMS) for Sign.

Earlier this month, some Twilio workers fell for SMS phishing made to appear like a reputable message from the corporate’s IT division. The attacker managed to entry data associated to 125 Twilio buyer accounts, and Sign’s was apparently one in every of them.

This allowed the attacker to gather the cellphone numbers of 1,900 registered Sign customers or the SMS verification code they used to join Sign.

“Throughout the window that an attacker had entry to Twilio’s buyer help programs, it was potential that they tried to log the cellphone numbers they accessed on one other machine utilizing the SMS verification code,” the Sign staff defined. .

As famous above, the attacker managed to re-register no less than one of many three numbers he was explicitly searching for.

“All customers can relaxation assured that their message historical past, contact lists, profile data, who they blocked, and different private information stay non-public and safe and weren’t affected,” the staff famous. That is as a result of that information is saved on the customers’ machine and Sign has no entry to or copy of it. “And this data is actually not out there to Twilio, or by way of entry quickly gained by Twilio attackers,” the staff added.

Sadly, in these instances the place the attacker was in a position to re-register an account, they may impersonate the person by sending and receiving Sign messages from that cellphone quantity.

Sign notifies doubtlessly affected customers of this breach instantly through SMS. The corporate has deregistered Sign on all of the units these 1,900 customers are presently utilizing (or have been registered on by an attacker) and is asking them to re-register Sign with their cellphone quantity on their most popular machine.

Along with that, they urge you to allow log lock (Sign Settings (profile) > Account > Log Lock) on your account, which is a function that helps forestall this sort of account takeover.

The ramifications of the Twilio hole

“The kind of telecom assault suffered by Twilio is a vulnerability that Sign developed options like Sign PIN and registration lock to guard towards. We strongly advocate customers to allow registry locking. Whereas we do not have the flexibility to instantly repair points impacting the telecommunications ecosystem, we’ll work with Twilio and doubtlessly different suppliers to strengthen their safety the place it issues to our customers,” the staff concluded.

After the Twilio breach, the corporate mentioned different corporations have been equally focused.

Cloudflare confirmed that they have been amongst them, however fortunately for them, the attacker was blocked by Cloudflare’s use of bodily safety keys.

It appears doubtless that we’ll be listening to in regards to the Twilio hole branching for a while.

1,900 Signal users exposed following Twilio breach