What is SIM Swapping?

SIM swapping compromises mobile accounts. Learn how this attack works and strategies to protect your mobile identity.
Author: SentinelOne Updated: July 23, 2025

SIM swapping is a technique used by attackers to take control of a victim’s phone number. This guide explores how SIM swapping works, its implications for security, and strategies for prevention.

Learn about the importance of securing personal information and using multi-factor authentication. Understanding SIM swapping is crucial for protecting against identity theft and fraud.

SIM swapping attacks represent a vulnerability in two-factor authentication (MFA/2FA). As a result, it has led to high-profile breaches, financial losses, and identity theft cases. In the current threat landscape, SIM swapping has become an attractive tool for hackers seeking to infiltrate cryptocurrency wallets, social media accounts, and financial institutions.

A Brief Overview & History of SIM Swapping

SIM swapping, a term that has garnered increasing notoriety in recent years, is a sophisticated and malicious technique employed by cybercriminals to gain unauthorized access to a victim’s mobile phone number and subsequently infiltrate sensitive accounts and data. It involves convincing a mobile carrier to transfer the victim’s phone number to a SIM card under the attacker’s control, thereby providing the attacker with the ability to intercept SMS-based two-factor authentication codes and reset passwords. This seemingly straightforward yet devastatingly effective tactic exploits the trust that mobile carriers have historically placed in customers’ requests for SIM card changes, making it a serious vulnerability in the security landscape.

The origins of SIM swapping can be traced back to the mid-2000s when it was primarily a tool used by hackers and scammers to engage in identity theft and wire fraud. Over the years, the technique has evolved, becoming more sophisticated and refined. Nowadays, it has emerged as a pervasive and damaging threat to individuals, businesses, and even high-profile personalities. Its usage has expanded from simply gaining unauthorized access to email or social media accounts to infiltrating cryptocurrency wallets, where attackers can steal vast sums of digital currency. Moreover, it is employed in financial fraud, online banking, and other malicious activities, often with far-reaching consequences.

Understanding How SIM Swapping Works

SIM swapping begins with the attacker identifying a target. This might involve researching the victim online to find personal information, including their mobile phone number, carrier, and even answers to security questions.

Armed with this information, the attacker initiates a social engineering campaign. They impersonate the victim and contact the victim’s mobile carrier’s customer support. They may use various tactics to convince the carrier that they are the account holder and need a new SIM card. Common tactics include pretending to have lost the original SIM card or claiming to need a replacement for a damaged card.

Once the attacker successfully contacts the carrier, they provide the victim’s information, including the mobile phone number and any additional details that may be requested. If the attacker is convincing enough, the carrier may issue a new SIM card without properly verifying the caller’s identity.

With the new SIM card in hand, the attacker inserts it into a device they control. This device is often a spare phone or a SIM card reader/writer. The attacker then activates the new SIM card, essentially taking over the victim’s phone number.

Once the victim’s phone number is under the attacker’s control, they can intercept SMS messages and phone calls. This is where the real damage can occur. If the victim uses SMS-based 2FA, the attacker can receive the authentication codes sent to the victim’s number, granting them access to the victim’s accounts. The attacker can also use the stolen phone number to reset passwords for various accounts, taking over email, social media, and financial accounts.

With access to the victim’s accounts, the attacker can engage in a range of malicious activities, from stealing sensitive information and funds to conducting identity theft and fraud. To avoid detection, attackers may attempt to lock the victim’s SIM card or otherwise disrupt the victim’s access to their phone number. They may also quickly change account recovery options, making it harder for the victim to regain control.

It’s important to note that SIM swapping is not a guaranteed success for attackers. Mobile carriers are increasingly implementing more robust authentication and verification procedures to prevent such attacks. For instance, they might require additional security questions or a physical visit to a store for SIM card replacement. However, it remains a significant concern due to the potential harm it can cause.

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Exploring the Use Cases of SIM Swapping

Perhaps the most well-documented use of SIM swapping is its role in cryptocurrency theft. Cybercriminals target individuals known to hold substantial cryptocurrency assets and use SIM swapping to gain control of their mobile numbers. Once in control, they intercept two-factor authentication codes and gain access to cryptocurrency wallets, resulting in significant financial losses. The significance of these attacks lies in the substantial financial stakes involved and the relatively irreversible nature of cryptocurrency transactions.

SIM swapping has also been utilized to hijack high-profile social media accounts. Hackers gain control over a victim’s phone number to reset passwords, effectively taking over their social media profiles. This can lead to reputational damage, spread misinformation, and even have broader societal implications when influential figures are targeted.

In more generalized instances, SIM swapping is used for identity theft and financial fraud. Attackers compromise victims’ mobile numbers, access email accounts, and manipulate password resets to infiltrate bank accounts, credit cards, and online services. The consequences extend to financial loss, compromised personal information, and reputational damage.

SIM swapping can also lead to the unauthorized access of sensitive business information. For individuals working in corporate environments, having their mobile number compromised can provide hackers with access to corporate email accounts and other sensitive data. This presents a significant security risk for businesses, particularly if employees have access to proprietary or confidential information.

In response to the escalating threat of SIM swapping, businesses and individuals are taking proactive measures to secure against its risks:

  • Enhanced Authentication Methods – One of the most crucial steps is moving away from SMS-based two-factor authentication (2FA) and adopting more secure methods, such as time-based one-time passwords (TOTP) generated by authenticator apps or hardware tokens. These methods are not reliant on SMS, making it significantly more challenging for attackers to intercept authentication codes.
  • Account Recovery Protocols – Individuals and businesses are revisiting their account recovery options. Rather than relying solely on mobile numbers for account recovery, they are adding alternative methods, like backup email addresses and security questions. This adds an extra layer of security, making it more difficult for attackers to take control of accounts.
  • Mobile Carrier Security Measures – Mobile carriers are increasingly implementing stronger identity verification processes before issuing a new SIM card or transferring phone numbers. They are also working on improving their customer support training to detect and prevent fraudulent SIM swap attempts. Additionally, some carriers offer services that allow customers to set up PINs or passphrases to protect their accounts from unauthorized changes.
  • Security Awareness and Education – Raising awareness about SIM swapping and its risks is crucial. Both businesses and individuals need to educate themselves and their employees about the potential threats and how to protect against them. Regular security training and reminders about best practices can go a long way in reducing the risk of falling victim to SIM swapping attacks.

Conclusion

SIM swapping has emerged as a serious and evolving threat in the digital age, with real-world use cases that demonstrate its potential for financial loss, reputational damage, and compromised security. The response to this threat involves the adoption of more secure authentication methods, robust account recovery protocols, cooperation with mobile carriers, and ongoing security awareness efforts, all aimed at mitigating the risks associated with SIM swapping.

SIM Swapping FAQs

What is SIM Swapping (SIM jacking/hijacking)?

SIM swapping is when attackers trick your mobile carrier into transferring your phone number to their SIM card. They impersonate you using stolen personal information and social engineering tactics to convince customer service representatives.

Once successful, all calls and texts meant for you go to their device instead, giving them access to two-factor authentication codes. It’s also called SIM jacking, SIM hijacking, or port-out scams.

How Does a SIM Swap Scam Work?

Attackers start by collecting your personal information through phishing, data breaches, or social media. They use these details to contact your mobile carrier, claiming they need a replacement SIM because their phone was lost or damaged.

If they have enough convincing information, the carrier transfers your number to their SIM card. Your phone loses service while theirs receives all your calls and messages, including banking verification codes.

What Personal Information do Attackers Need for a SIM Swap?

Attackers need your full name, date of birth, address, and phone number as basic requirements. They also target security question answers, your Social Security number’s last four digits, and account PINs. Social media profiles provide valuable information like pet names, hometown details, and family members’ names.

Data breaches often give them additional details like previous addresses and account history that make their impersonation more convincing.

Why is SIM Swapping so Dangerous?

SIM swapping bypasses SMS-based two-factor authentication, which many services still rely on for security. Once attackers control your number, they can reset passwords for email, banking, and cryptocurrency accounts. They intercept verification codes sent to your phone, allowing them to drain bank accounts and steal digital assets.

The attack often goes unnoticed until significant damage is done, and recovery can be extremely difficult.

Which Accounts are most at Risk from SIM Swapping?

Cryptocurrency wallets and trading accounts are prime targets because transactions can’t be reversed. Banking and financial accounts that use SMS verification are also high-risk. Email accounts become entry points to other services through password resets.

Social media accounts, cloud storage services, and any platform using phone-based authentication are vulnerable. Business accounts with administrative privileges face even greater risks.

How can you Prevent SIM Swapping?

Use app-based authentication like Google Authenticator instead of SMS whenever possible. Set up a strong PIN or password with your mobile carrier and enable account takeover protection. Limit personal information shared on social media and be cautious about phishing attempts.

Consider using a dedicated phone number for sensitive accounts or switching to a more secure carrier. Regularly monitor your accounts and set up alerts for suspicious activity.

What Steps Should you take if your SIM gets Hijacked?

Immediately contact your bank and credit card companies to freeze your accounts. Change passwords on all important accounts using a different device or internet connection. Call your mobile carrier to report the unauthorized transfer and reclaim your number.

File a police report since SIM swapping is identity theft and fraud. Contact credit bureaus to freeze your credit and prevent new accounts from being opened.

Can ESIMs Mitigate SIM Swap Scams?

eSIMs can provide better security because they’re embedded in your device and harder to transfer. However, they’re not completely immune since carriers can still port numbers between devices. The main advantage is that attackers can’t physically steal an eSIM like traditional cards.

But if carriers don’t have strong verification procedures, eSIM swaps can still happen through social engineering. You still need to implement other security measures like app-based authentication and carrier account protection.

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