What is sim swapping?
SIM swapping is when an attacker convinces your mobile carrier to move your phone number onto a SIM they control. Every SMS verification code then arrives on their device instead of yours. It is the single strongest argument against using SMS as a second factor for anything valuable.
- Topic
- Attacks
- Also called
- SIM swap attack, SIM jacking
- Reading time
- 1 min
- Reviewed
On this page
How the attack runs
It is social engineering against the carrier, not a technical exploit. The attacker gathers enough personal detail, often from previous breaches, to pass the carrier's identity check. They then report a lost phone and request a transfer. The first sign for the victim is usually a phone that suddenly loses signal.
How to reduce the risk
Move your second factor off SMS wherever possible and use an authenticator app or security key. Add a port-out PIN or account lock with your carrier; many carriers support one. Remove your phone number as a recovery method on accounts that let you use something else.
Sources
These primary references support the terminology and current security guidance used in this definition.
