A SIM swap is when an attacker tricks your mobile carrier into moving your phone number to their SIM card. Once they control your number, they receive your text-message codes and can reset passwords and bypass SMS two-factor authentication — a common way crypto accounts get drained. Here's how to defend against it.
How the attack works
Using stolen personal details or social engineering, the attacker convinces your carrier to "port" your number to a SIM they hold. From that moment, your calls and texts go to them, including any SMS login or reset codes [1]. With those codes, they can get into email and exchange accounts that rely on SMS for security and move funds out. A telltale sign is your own phone suddenly losing all signal for no reason [2].
How to protect yourself
The bottom line
The core weakness a SIM swap exploits is relying on SMS for security. The strongest defense is to switch your two-factor authentication from text messages to an authenticator app or, better still, a hardware security key — neither of which moves with your phone number. Add a PIN or port-out lock with your carrier, avoid publicizing your number, and if your phone unexpectedly goes dark, contact your carrier immediately. To keep learning the fundamentals, follow more from Bitbase Academy.
Disclaimer: This article is educational content from Bitbase Academy, provided for information only. It does not constitute investment, trading, tax, or financial advice. Crypto assets are volatile; assess your own risk. Written as of June 2026; refer to the latest official information.
References
[1] Coinbase, "What is a SIM swap?" coinbase.com
[2] Ledger, "Protecting your accounts." ledger.com
