RFID access cards are easy to use, and just as easy to clone. Someone can copy your card in minutes and gain access to secure areas with the right tools. This guide will tell you how RFID cloning works, the tools used to clone your RFID card, and how to protect your cards from being cloned.

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What is RFID Card Cloning Technology

This happens when someone copies the data on your RFID card and puts it on another card or device. In essence, they duplicate your original and make a copy that works exactly the same. The cloned card can do the same if your card opens doors, buys stuff, or accesses secure systems.

How to Clone RFID Cards

Let’s break this down step by step. The first is cloning RFID cards, which is simply copying the information from one card to another. Imagine it as a duplicate house key, except for electronic access cards.

Low frequency (125kHz) and high frequency (13.56MHz) are two types of RFID cards people try to copy. It depends on which type you are working with, the way you clone them.

1. Cloning Low-Frequency (125kHz) RFID Cards

These are easiest to clone. They are still in use in a lot of old apartment buildings and garages.

What You Need:

A cheap handheld RFID copier (which you can find online)
A blank 125kHz card or key fob

How to Do It:

Read and write the copier – You will have a ‘read’ and ‘write’ button.
Put the card on the copier and press “read” for scanning the original card. Wait for the beep.
Swap in the blank card or fob – Place the blank card.
The copier copies the data and then press “write”. You’ll hear a beep again.

And that’s it. Your blank card now works just as the original.

Example:

For instance, you have a key fob to open your apartment gate. If it’s a 125kHz card, you could buy a $20 cloner and make a spare in less than a minute.

2. Cloning High-Frequency (13.56MHz) RFID Cards

They are more secure and used in newer systems, such as office or hotels. However, some of them are still cloneable, but it is more labor intensive, and some of them are not cloneable at all, such as newer MIFARE Classic cards.

What You Need:

A computer with Linux or Windows
A card reader/writer like the ACR122U
Software like mfoc (a free tool)
A blank 13.56MHz card

How to Do It (Simplified):

Insert your reader – Plug it into your laptop and install the software.
Try to ‘crack’ the card’s memory using the software and scan the original card. This can take a few minutes.
After cracking the card, save the card’s info as a file.
Copy to a blank card – Use a command to write the data from the card to a new card.

Note:

It only works with some high frequency cards — not all. Cards like DESFire or iCLASS are much harder (usually impossible) to copy without expensive tools.

3. Pro Tools: Proxmark3

The Proxmark3 is like a Swiss Army knife for RFID, if you want to go deep. It is compatible with low and high frequency cards. It has a learning curve and requires some coding skills.

Unless you’re testing security systems or in cybersecurity, most people don’t start here.

If you’re just starting and your card is 125kHz, cloning it is super simple. Only for something more advanced, you will need to do some homework and use better tools. But only do it legally — either for your own card or with permission.

How RFID Cards Cloning Works

Chips on RFID cards store small amounts of data. The data is sent over radio waves when you hold your card near a reader. However, not all RFID cards are secure.

That data is often sent unencrypted by older cards, especially the ones that use 125kHz low frequency signals. It means that anyone can grab the info without needing a password. It’s the same as screaming your email password in a room, anyone who can hear it has your password.

Cards these days are a bit more sophisticated. Encryption and 2 way authentication are used so the card and reader have to ‘shake hands’ before anything is shared.

The problem? Still, a lot of places still use outdated cards because they’re cheaper and easier to manage.

Can Every RFID Card Be Cloned

However, this does not mean that all RFID cards are easy to copy. Some are basically open books. Others are locked tight.

Easy to Clone

Widely used and super easy to duplicate is HID Prox (125kHz)
MIFARE Classic 1K: Old, has some security which can be cracked

Harder to Clone

MIFARE DESFire EV2
HID iCLASS SE or SEOS
FeliCa cards (used in Japan)

In fact, these more advanced cards use encryption, which is much harder to clone RFID cards without professional grade equipment (and a lot of time and effort).

Pro tip: If you only see the label “HID Prox” or “125kHz” on your card, you may be due for an upgrade.

Is it Legal to Clone RFID Access Card?

And this is a question that comes up a lot, and the answer depends on what you’re doing and why.

When It Might Be Legal

You are copying your own card: If you want a spare to keep in your gym bag. If you have the card and there are no restrictions against duplicates, you’re probably okay.
If you are in charge of your company’s IT security, you are testing your own system, including if someone could clone RFID cards in your setup.

When It’s Not Okay

Unauthorized access is copying someone else’s card and could result in criminal charges.

This is why you use a cloned card to enter restricted areas: Even if you aren’t doing anything wrong, bypassing security with a copied card is usually trespassing or worse.

So bottom line: Don’t do it without permission when in doubt.

Important Notes When Copying RFID Cards

Here are some things to remember if you have a credible reason to clone RFID cards.

Know Your Card Type

The RFID cards can be of two types:

Low-frequency (LF): These are 125kHz cards. Less secure and easy to copy.
MIFARE and NFC cards are high frequency (HF). Some are simple to duplicate, some aren’t.

Find out what type of card you have by looking at the back of your card or ask your building’s admin.

Choose the Right Tools

Repos for RFID readers and writers abound. A couple of popular ones are here below.
Very powerful but requires some technical know how: Proxmark3
They are easier to use, but the main usage is for high frequency (RFID chip) cards.

These are the tools that you use to scan, analyze and copy card data, but as always, do so responsibly.

Don’t Forget Testing

Clone RFID cards for legit reasons (most likely, to back up your apartment access key) and test the copy somewhere safe first. You don’t want to be locked out from your account and in case you forget, accidentally trigger a security alert.

Conclusion

Although RFID is convenient, it has some security risks. If you are using an old card type, there is a chance that someone can clone your card without your knowledge. For that reason, it’s important to know how cloning works, how to identify vulnerable cards, and how to keep yourself safe.

Whether you want to clone RFID cards for curiosity or out of necessity — i.e. managing access for a building — understanding how you can clone RFID cards can help you make better decisions. All you have to do is remember not to do things unethical, illegal and unsafe.