Methods to hack a SIM, how it affects us and how to protect ourselves

The SIM card, a target for cybercriminals

Something fundamental for our day to day, to be able to connect to the Internet from the mobile, is the SIM card. This small device has linked our personal data, a number and, in turn, serves to register multiple services and platforms.

For example we can mention the use of the two-step authentication. More and more programs that we use frequently and that need to confirm our identity through a message in which they send us a code. A way to verify that we really are the legitimate user.

This makes hackers set your sights here. If they manage to hack a SIM card, if they manage to take control of our mobile number, they will be able to access many services. This can serve to steal data and compromise our privacy.

How they can attack a SIM

To attack a SIM card they can use different methods. We have already indicated that cybercriminals are constantly updating and looking for new ways to achieve their goal. It is important to know which are the main ones in order to protect ourselves and avoid making mistakes that may affect us.

SIM Swapping

One of the most widely used methods by hackers to attack a SIM card is what is known as SIM Swapping. It is a fraud of card spoofing. Basically what the attacker does is get the operator to transfer a phone number to another device.

For this to happen, the attackers will have to collect personal information of the victim. At the end of the day what they are going to do is go through them. They are going to pretend to be a customer requesting to transfer their number. This can be obtained through a previous Phishing attack, in which they collect all kinds of personal data that they will need.

Later you will contact the operator to request that change. It will give the data and it will indicate that the mobile has been stolen or lost and that therefore you need a new SIM card.

This problem can affect any user. It is therefore very important to prevent our data from being available on the Internet to anyone. We must always protect personal information, use security tools and of course common sense so that data is not leaked on the Internet.


Another technique they can use to attack a card is what is known as SIMjacker. In this case they will be based on an existing vulnerability. It is something that appeared a few years ago and that affected certain users and it can you get hacked by a text message easily.

The attacker will send a text message with a code. Should the victim open it, the hacker could exploit that vulnerability. You could use it to spy on device usage, such as reading SMS or monitoring calls.

There are some telephone operators that use a tools kit of applications for the SIM. For example an integrated browser to be able to access the network at any given time. It is just this kit that can exploit this type of attack. Of course, as long as it is vulnerable.

However, it is a very specific attack that affected certain users and operators. Nowadays the truth is that the majority use other browsers and it is rare that they are affected by problems like this. Of course, it is another question to take into account.

Physical cloning of the card

Undoubtedly another way they can use is the physical cloning of the card. It basically means that an attacker is going to create a second SIM identical to the main one. For this they will have to physically access that card and copy it.

Once this is done, the attacker will be able to use the copied card as if it were us. You would have access to the messages, so you could bypass the two-step authentication. It is an undoubtedly important problem.

What to do to avoid attacks on the SIM card

We have seen some methods that they could use to attack our SIM card. It is something that logically puts our privacy at risk and could allow a third party to access personal data and information. We are going to see now some steps to take into account to protect ourselves.

Common sense and avoiding mistakes

Without a doubt the most important thing will always be the common sense. We must avoid mistakes that may affect our security. For example, we must avoid clicking on links that come to us by SMS and that we do not really know if they are safe or not. It is a method that they used for SIMjacking attacks, as we have seen.

Therefore, we must always keep common sense in mind, reduce the possibility that an attacker may interfere with the proper functioning of the equipment and, ultimately, achieve the best possible protection.

Always use a secure PIN code

Another very important question is to use a good PIN code that protects our device. In case of theft or loss of the device, something that can prevent identity theft attacks, being able to access our accounts, is to have a password.

This, although it could be exploited by brute force and other methods, at least gives us enough time to lock the SIM. It is undoubtedly a protection, a safety barrier, that cannot be missing. We should never use a simple PIN code, of the type 1234.

Use 2FA for safety

Be careful where we take to fix the mobile

We have also talked about the physical cloning from a SIM card. In this case, the attacker will have physical access to that card in order to clone it. One possibility is that, when taking the mobile to repair to a store, they could attack us in this way. This means that we must always be aware of where we send our mobile for repair, especially if we decide to opt for Internet pages where they do not really offer guarantees.

Protect device

This is a general thing, to avoid any type of attack. We always must keep safe on our devices. This means that we are going to use security programs to avoid malware, have strong passwords and any tool that can help us increase security.

Ultimately, these are some methods that they can use to attack a SIM card. Luckily it is not a very common problem, although it is true that there have been cases. It is therefore advisable to know how to protect ourselves.

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