If you haven’t already taken steps to prevent being a victim of a SIM cloning attack, please do so now!

If you haven’t already taken steps to prevent being a victim of a SIM cloning attack, please do so now! I had assisted a customer yesterday, whose SIM was cloned and the hackers gained access to his business checking account, and he lost a substantial amount of money.
 
There are two steps that you can take to prevent this from happening to you!
 
1.    You can lock your SIM on your phone. Warning! It’s a little counterintuitive. There’s probably already a default PIN on your phone, and in my case for AT&T, it’s 1111. So, you need to enter the default code for whatever your carrier is and then you need to change it to a new four-digit PIN that has nothing to do with your phone or you that has not been used anywhere else. If you enter the default PIN incorrectly because you think you’re entering a new PIN, then you can lock your phone, and the service for your phone will turn off, so make sure you follow the steps correctly. Also, you can speak to your carrier about how to lock your SIM.
 
See this for more info: https://www.att.com/support/article/wireless/KM1000485/
 
2.    You can also put a lock on your account for the phone number in your portal for your carrier, and that will also give you an extra layer of protection against having any phone number or account changes take place without confirmation from you.
 
https://about.att.com/story/2025/wireless-account-lock.html
 
Now, the customer that I helped had an external bookkeeper, and that person is a PC Windows user, so I semi-suspect that that party was the one where the password to the bank was obtained, and then once they had the password to the bank, all they had to do was clone the owner’s SIM card. The hackers seem to be going for business owners who bank at a certain top five corporate bank. This is the third large money hack that I’ve seen for business owners who bank at this bank, though the two previous hacks did not appear to be SIM cloning attacks. Also in this case, the hackers also were targeting this customer’s partner, so I suspect they were going after their personal money as well!
 
Also, it’s important to remember that the SMS two-factor authentication codes are not exactly secure and may not be the best way to secure your banking information. If your bank will let you use a two-factor code generator, that might be a better option, use a passkey where your phone or Mac to authenticate using a built-in feature, such as Face ID, Touch ID fingerprint, you can also use a hardware key that you have to plug into your computer in order to log into your bank.