SIM Card Hacking: What It Is, How It Works, and How to Protect Yourself

This report explains how attackers hijack mobile phone numbers via SIM swapping, SIM cloning, and the Simjacker vulnerability to bypass MFA, steal PII/PHI, and gain access to financial and enterprise accounts; it outlines indicators of compromise, real-world impact (including a 2024 SEC SIM swap), and practical mitigations for individuals and organizations such as using app-based authenticators, SIM PINs, monitoring device activity, and engaging Supply Chain Detection and Response.