All terms
An attacker takes over your phone number to defeat SMS two factor authentication.
The attacker convinces your carrier to port your number to their SIM. Every SMS code then goes to them, including exchange login and withdrawal codes.
This is why SMS is the weakest form of two factor authentication, and why it should never protect an exchange account holding real money.
Use an authenticator app or a hardware security key instead of SMS wherever the option exists.
That your carrier will protect you. The attack works by persuading a person in a shop or a call center to move your number, and it succeeds often enough to be an industry. Move your two factor off SMS rather than trying to secure the phone number.
Common questions
How do attackers take over a phone number?
Does an authenticator app stop a SIM swap?
Where this comes up on the site
The guides that actually use this word, rather than a list of everything we have written.
Where to go next
More security terms
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