SIM Swapping Attacks

The cluster discusses SIM swapping vulnerabilities, how attackers exploit mobile carriers to hijack phone numbers, related security measures like SIM PINs and IMEI tracking, and provider protections such as those from Google Fi and T-Mobile.

📉 Falling 0.4x Security
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#4111
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Keywords

US USIM IMHO activate.org PIN OPSEC SMS LTE SIM contextis.com sim phone card sims phones pin id fi mobile swapping

Sample Comments

silisili Feb 28, 2023 View on HN

Not only sim swaps, but also phone unlock codes IIRC.

gruez Jul 4, 2023 View on HN

While what you described is theoretically possible, I've never seen any mobile provider implement it. The reason is fairly simple: if you cared about the security of your sim, you'd set a sim pin. If you don't, you don't set a pin. Requiring reauthentication every time your IMEI is going to cause a massive increase in support calls for very little security gain.

edent Jul 7, 2016 View on HN

Wonder how they manage SIM distribution / authentication?

justsomehnguy Oct 31, 2022 View on HN

Only if you somehow acquired a SIM card which doesn't 'belong' to anyone.

ktsmith May 21, 2019 View on HN

It's worse than this though. My colleague had his sim replaced by an attacker in October of last year even though his account had a note on it specifically to prevent this without the account holder being present and showing photo id. Not only can the customer service rep at your carriers store do this but so can the phone reps at all the other stores that sell phones for your carrier such as best buy. The bottom line is that SMS/phone numbers shouldn't be an identifying factor fo

phyphy Jan 25, 2024 View on HN

Can anyone explain why SIM swapping works? Do telecom companies in US allow you to buy a new SIM without a government issued ID?

chendragon Jan 18, 2020 View on HN

Wouldn't it be trivial for the company to track where the SIM is being used to find out who's done this?

megous Jun 10, 2025 View on HN

They can just take your number anyway if you ever insert a SIM, since they control "your" phone.

darkhorn Sep 11, 2019 View on HN

This is mobile operator problem, not Twitter. How on earth the mobile operator can hand a SIM card to someone else?!

three_seagrass Aug 4, 2020 View on HN

Pixel phones are now preventing sim swapping, IIRC, and maybe a few others.