The SIM Port attack is a type of account takeover fraud that generally targets a weakness in two-factor authentication & two-step verification, where the second factor or step is an SMS or a call placed to a mobile telephone.

Article:https://medium.com/coinmonks/the-most-expensive-lesson-of-my-life-details-of-sim-port-hack-35de11517124?sk=4c29b27bacb2eff038ec8fe4d40cd615