The attack chain is as follows: the threat actors masquerade as “Signal Support” or a support chatbot named “Signal Security ChatBot” to initiate direct contact with prospective targets, urging them to provide a PIN or verification code received via SMS, or risk facing data loss.

Should the victim comply, the attackers can register the account and gain access to the victim’s profile, settings, contacts, and block list through a device and mobile phone number under their control. While the stolen PIN does not enable access to the victim’s past conversations, a threat actor can use it to capture incoming messages and send messages posing as the victim.

That target user, who has by now lost access to their account, is then instructed by the threat actor disguised as the support chatbot to register for a new account.

Don’t give your signal PIN to someone via text? And even if you did, they still don’t have your message history.