SIM swap is an attack method in which an attacker takes over a victim's cell phone number by convincing a telecommunications service provider to transfer the victim's phone number to a SIM card owned by the attacker. Once successful, the attacker can use the phone number to take over the victim's online accounts, including crypto wallets, bank accounts, and other platforms that use two-factor authentication via SMS.

In SIM swap attacks, attackers usually utilize the victim's personal information obtained from other sources, such as social media or phishing attacks, to trick telecom service providers into believing they are the rightful owner of the phone number. After gaining control of the phone number, the attacker can reset the passwords of important accounts that use SMS-based two-factor authentication (2FA). This is especially dangerous for crypto users because many digital wallets, crypto exchanges, or DeFi platforms use 2FA as an additional layer of security. SIM swap can lead to the theft of digital assets or highly sensitive personal information. To avoid this attack, users are advised to use more secure authentication methods, such as token-based authentication apps.