---
url: 'https://www.corbado.com/faq/sim-swapping-sms-authentication-risk'
title: 'How does SIM swapping compromise SMS authentication?'
description: 'SIM swapping allows attackers to take control of a user’s phone number, intercept SMS OTPs, and bypass authentication, leading to account takeovers.'
lang: 'en'
keywords: 'SIM swapping, SIM swap attack'
---

# How does SIM swapping compromise SMS authentication?

## How Does SIM Swapping Compromise SMS-Based Authentication?

SIM swapping is a **fraudulent attack** where cybercriminals **take over a user’s mobile
phone number** by transferring it to a new SIM card. This enables them to **intercept
SMS-based authentication codes** (OTPs) and gain **unauthorized access to user accounts**,
which is why many people prefer using a
[virtual number](https://dialaxy.com/virtual-phone-number/?utm_source=corbado.com&utm_medium=refferal&utm_campaign=support)
for added security.

### How Does a SIM Swap Attack Work?

1. **Target Identification:** The attacker identifies a victim with valuable accounts
   (e.g., [banking](https://www.corbado.com/passkeys-for-banking), email, crypto
   [wallets](https://www.corbado.com/blog/digital-wallet-assurance)).
2. **Social Engineering or Hacking:**

- The attacker **impersonates the victim** and contacts the mobile carrier.
- Using **stolen personal data** (like name, date of birth, or address), they trick
  customer support into **transferring the victim’s phone number** to a SIM card they
  control.

3. **SMS OTP Interception:**

- The victim's phone loses service.
- The attacker **receives all SMS messages**, including authentication codes.

4. **Account Takeover:**

- The attacker **bypasses SMS-based authentication**, gaining full access to sensitive
  accounts.
- This often results in **identity theft, financial fraud, and data breaches**.

### Why Is SIM Swapping a Major Risk for SMS Authentication?

🚨 **Bypasses 2FA Security:**

- Even if users have **two-factor authentication (2FA)** enabled via SMS, attackers can
  **bypass it** and gain access.

💰 **Leads to Financial Fraud:**

- **Banking, cryptocurrency, and payment accounts** are prime targets for
  [SIM swap](https://www.corbado.com/glossary/sim-swap) attacks.

🔓 **Weak Carrier Security:**

- Mobile providers **lack strong authentication measures**, making **social engineering
  attacks** successful.

🔄 **Hard to Detect in Real-Time:**

- Victims **only notice** after losing service or when their accounts are already
  compromised.

### How to Protect Against SIM Swapping?

🔹 **Avoid SMS-Based Authentication:** Use a more secure method like **passkeys** or
app-based authentication.\
🔹 **Enable Carrier PIN Protection:** Set up a **port-out PIN** with your mobile
provider.\
🔹 **Monitor for Unexpected Service Loss:** A sudden **loss of phone service** could
indicate a [SIM swap](https://www.corbado.com/glossary/sim-swap) attack.

### Passkeys: The Ultimate Protection Against SIM Swapping

Unlike SMS OTPs, **passkeys use public-key cryptography**, making them:\
✅ **Phishing-resistant**\
✅ **Not tied to phone numbers**\
✅ **Secure against SIM swap attacks**

Businesses and users looking to **enhance security and eliminate account takeovers**
should transition to **passkeys** as a **more secure authentication solution**.

## Read the full article