How to avoid a SIM swap attack?

Understanding SIM Swap Attacks

A SIM swap attack occurs when a malicious actor convinces a mobile carrier to transfer a victim’s phone number to a new SIM card under the attacker’s control. Once the number is transferred, the attacker can intercept two-factor authentication (2FA) codes, password reset links, and other sensitive communications. This is particularly dangerous for cryptocurrency holders, as access to a phone number can often be the key to recovering or accessing digital wallets and exchange accounts.

Victims often lose access to their crypto accounts within minutes, with attackers quickly draining funds from linked wallets or exchanges. Understanding how this attack works is the first step toward preventing it.

Recognizing the Warning Signs

Before a SIM swap attack fully executes, there are often subtle signs that something is wrong. These signs may include unexpected service disruptions, receiving notifications from your carrier about account changes, or being logged out of accounts that rely on SMS-based 2FA.

• Sudden loss of cellular service without explanation
• Email or SMS notifications from your carrier indicating account modifications
• Login issues with accounts that use phone number verification

If any of these occur, it's crucial to act immediately by contacting your mobile provider and initiating a security lock on your account.

Securing Your Mobile Carrier Account

Most SIM swap attacks succeed due to weaknesses in customer service verification. Attackers often impersonate victims by answering security questions or bribing customer support representatives.

To mitigate this risk:

• Set up a PIN or password with your carrier that must be provided before any account changes are made
• Avoid using publicly available information as answers to security questions (e.g., birthplace, pet names)
• Enable account alerts so you're notified of any changes to your mobile account

Some carriers also offer the option to lock your SIM card from being ported to another device, which can be a critical defense mechanism.

Protecting Your Cryptocurrency Accounts

Since many cryptocurrency platforms rely on SMS-based 2FA, they are especially vulnerable to SIM swap attacks. To enhance security:

• Switch to an authenticator app like Google Authenticator, Authy, or hardware-based 2FA tokens
• Use a strong, unique password for each exchange or wallet service
• Enable email and SMS alerts for login attempts and fund transfers

It’s also wise to avoid linking your phone number to multiple accounts. If you must use SMS verification, consider using a secondary phone number specifically for sensitive services.

Using Cold Storage and Backup Strategies

For serious cryptocurrency holders, moving funds to a cold wallet is one of the most effective ways to protect against SIM swap attacks. Cold wallets are offline storage solutions that cannot be accessed remotely.

• Store the majority of your crypto in a hardware wallet like Ledger or Trezor
• Keep recovery phrases offline and secure — never store them digitally or in the cloud
• Distribute your holdings across multiple wallets to limit exposure

Additionally, ensure that backups of your wallet recovery phrases are stored in multiple secure locations, such as a safe deposit box or encrypted offline storage.

Responding to a SIM Swap Incident

If you suspect a SIM swap has occurred, time is critical. Begin by contacting your mobile carrier immediately to regain control of your number.

• Call your carrier using an official number — not one provided via SMS or email
• Report the incident to your cryptocurrency platforms and request account freezes
• Change all associated passwords and revoke any active sessions

You should also report the incident to relevant authorities, such as your local cybercrime unit or the Federal Trade Commission (FTC) if you're in the United States.

Frequently Asked Questions

What should I do if my carrier doesn't offer a SIM lock or PIN option?If your carrier does not support PIN or lock features, consider switching to a provider that offers stronger account security. Alternatively, use third-party services that offer SIM lock assistance or port protection.

Can I use an eSIM to prevent SIM swap attacks?While eSIMs are more secure than physical SIM cards, they still rely on the same carrier account. If an attacker gains access to your carrier account, they can still transfer your number to another eSIM. Therefore, securing your account with a PIN remains essential.

Is it safe to use my phone number for multiple crypto accounts?Using the same phone number across multiple platforms increases your risk. If one service is compromised, all linked accounts become vulnerable. It's safer to use separate numbers or authentication methods for each service.

How often should I update my carrier account security settings?Review and update your mobile carrier account security every 3–6 months. Ensure your recovery information is current, and confirm that your PIN or lock settings are still active.