SIM Swap

A SIM swap is a type of identity theft in which attackers fraudulently transfer a victim’s mobile number to a SIM card they control. In the context of Bitcoin, SIM swaps are used to bypass two-factor authentication (2FA), access exchange accounts, and reset passwords linked to phone numbers. Once an attacker gains control of a victim’s number, they can intercept verification codes and quickly drain bitcoin holdings. Bitcoin users are especially vulnerable because many exchanges and wallet services still rely on SMS-based 2FA, which becomes ineffective when a phone number is compromised. Attackers may trick mobile carriers through social engineering, stolen identity documents, or insider cooperation. After taking over the number, criminals target email accounts, exchange logins, and any service that uses SMS recovery features. Protecting against SIM swaps requires disabling SMS-based 2FA and replacing it with app-based or hardware authentication. For bitcoin holders, strong authentication and minimal reliance on phone numbers are essential defenses against SIM-swap-enabled theft.