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That tiny chip in your phone is a major security vulnerability. From remote exploitation to identity theft, SIM cards present risks that most people never consider. Learn how to protect yourself from SIM-based attacks.
A SIM (Subscriber Identity Module) card is a small computer that stores your cellular identity. It contains:
Security researchers have discovered serious vulnerabilities in SIM card technology that affect billions of devices worldwide.
CVE-2019-16256Allows attackers to track location, intercept calls, and retrieve sensitive data by sending specially crafted SMS messages to the SIM card's S@T Browser.
Similar to Simjacker, exploits the Wireless Internet Browser (WIB) on SIM cards to execute commands without user awareness.
Social engineering attack where criminals convince carriers to transfer your phone number to their SIM, gaining access to 2FA codes and accounts.
SIM cards can receive over-the-air updates that modify their behavior. Malicious updates could add surveillance capabilities.
The origin and supply chain of your SIM card matters. Here are security concerns related to foreign manufacturing.
Many SIM cards are manufactured in China, even for US carriers. The manufacturing process could include backdoors or surveillance capabilities.
SIM card operating systems (JavaCard, MULTOS) may contain code from foreign sources that hasn't been fully audited.
The encryption keys (Ki) programmed into SIMs during manufacturing could be retained by foreign manufacturers or governments.
SIM cards pass through multiple suppliers and distributors, creating opportunities for tampering before reaching consumers.
Understanding who makes SIM cards can help you make informed choices about your cellular security.
| Manufacturer | Country | Market Share | Status | Notes |
|---|---|---|---|---|
| Thales (Gemalto) | 🇫🇷France | ~30% | Safe | Major Western manufacturer, acquired Gemalto in 2019 |
| Giesecke+Devrient | 🇩🇪Germany | ~25% | Safe | German security company, trusted by major carriers |
| IDEMIA | 🇫🇷France | ~20% | Safe | Formed from merger of Morpho and Oberthur Technologies |
| Eastcompeace | 🇨🇳China | ~10% | Caution | Chinese state-owned enterprise, supplies some budget carriers |
| KONA I | 🇰🇷South Korea | ~5% | Safe | Korean manufacturer, supplies Asian markets |
SIM swap attacks happen quickly. Recognizing these signs can help you respond before attackers gain access to your accounts.
Follow these steps to reduce your risk from SIM-based attacks.
Set a PIN code that must be entered when your phone starts. This prevents unauthorized use if your SIM is stolen.
Set up an additional PIN or password that must be provided for any account changes, protecting against SIM swap attacks.
eSIMs are embedded in your phone and cannot be physically stolen. They also can't be swapped at a store without your authentication.
Watch for signs that your SIM or account may have been compromised.
SIM security is just one part of protecting your cellular identity. Explore more topics to build a complete security strategy.