Credit and debit cards with an embedded radio frequency identification (RFID) tag are now the norm. But this is only one area where RFID technology is used.

There are many other places where you use RFID technology, perhaps without even realizing it.

So what is RFID?

RFID is the use of radio waves to read, capture and interact with the information stored in a tag/tag. Tags are usually attached to objects and can be read from several meters. Also, the tag does not always have to be in line of sight to initiate an interaction.

An RFID tag is an easy way to give an object a unique identifier. Plus, they don't need an internal power source, while the tag can be as small as a black peppercorn. This means that they are easily implemented almost everywhere - hence their popularity.

How does RFID work?

The basic RFID system consists of two parts: a tag and a reader.

Label

The RFID tag has a built-in transmitter and receiver. The actual RFID component contained in the tag consists of two parts: an integrated circuit for storing and processing information, and an antenna for receiving and transmitting the signal. The RFID tag has non-volatile storage and may include either fixed or programmable logic to process transmission and sensor data.

Tags can be passive, active, or battery-powered passive.

Passive label is the cheapest option and does not contain a battery. The tag uses a radio transmission transmitted by the reader.

active label has a built-in battery that periodically transmits its credentials.

Rechargeable passive tag also equipped with a small built-in battery, but only activated when an RFID reader is present.

In addition, the label may be available only for reading or read/write. The read-only tag has a factory serial number used for identification in the database, while the tag read/write may have certain user data written to the label by the user.

Reader

An RFID reader is equipped with a two-way radio transmitter (transceiver), sometimes called an interrogator. The transceiver transmits an encoded radio signal to interact with the tag. The radio signal essentially wakes up or activates the tag. In turn, the tag's transponder converts the radio signal into usable power and responds to the reader.

We usually classify the type of RFID system by the type of tag and reader. There are three common combinations:

• Passive Reader Active Tag (PRAT): The reader is passive, it only receives radio signals from the active tag. Because the tag is powered by a battery, the receive/transmit range can be from 0 to 600m. Thus, PRAT is a flexible RFID solution.
• Passive Tag Active Reader (ARPT): the reader is active, transmitting a request radio signal, receiving authentication responses from passive tags.
• Active tag active reader (ARAT): the reader is active and interacts with active or battery passive tags.

In addition to the type of RFID system, RFID uses a set of adjustable frequency bands.

What is OPID?

Optical RFID (OPID) is an alternative to RFID that uses optical readers. OPID operates in the electromagnetic spectrum between 333 THz and 380 THz.

How much data?

The amount of information stored in an RFID tag varies. For example, a passive tag can only store up to 1024 bytes of information - that's just one kilobyte (KB). Ridiculous in terms of modern storage capacity, but enough to keep the full name, an identification number, birthday, SSN, information about credit card and much more. However, the aerospace industry uses passive microwave RFID tags with 8K storage to track the history of parts over time. They can store a huge amount of personal data.

General use of RFID

RFID tags are everywhere. Since they are easily attached to almost anything, have no need for energy, they are used in all areas of life, including:

• Item management and tracking
• Observation of people and animals
• Contactless payments
• travel documents
• Barcodes and security labels
• Health data management
• Timing

RFID is also making waves in the ever-growing smart home market. In 2010, the cost of RFID dropped significantly. At the same time, the reliability of RFID has increased due to the global shift to RFID standards. All of a sudden there was an extremely reliable but economical tracking or identification system.

Safety

The sudden surge of RFID has also caused security concerns. More recently, contactless payment cards with RFID tags have appeared. Unscrupulous people hacked contactless cards using portable payment terminals while the RFID-enabled card was in the target's pocket or wallet.

In the UK, another example involves RFID tags stored in passports. When first entered, the password for the new UK passport was cracked within 48 hours. In addition, there have been reports that the criminals were stealing the mail containing the new passport, scanning the RFID tags for the data, and then sending it further down their path.

RFID is here to stay

RFID is a huge industry. We use it almost every day. The package that arrived at your house, the card you paid for your dinner, the key card that opened the door, the smart home, the hand implant, and more all use RFID technology.

What are you using RFID for? Do you use it in your smart home? Have you bought an RFID blocking wallet? Let us know it in the comments below!

It is difficult to imagine a future without total control over everyone, however, apparently, for the next couple of decades, we can forget about the gaze of Big B. RFID technologies, electronic passports, biometric identifiers were on the same ship with the symbolic name "Titanic". Of course, that "one person was able to assemble the other will always disassemble" ©, so the electronic crafts of the inquisitive hands of test hackers could not stand it.

How reliable were DST (Digital Signature Transponder) chips, widely used (and used) in the automotive industry RFID. Here to make a small curtsy to the side RFID, about which quite a few copies have already been broken,
. However, the cheapest and therefore the most common variety of RFID chips, commonly referred to as tags, is most often considered. EPC (Electronic Product Code tag) and used for contactless identification of goods. By the way, speaking RFID it's not just labels EPC, but also a wide range of RF devices with diverse functionality. More expensive and advanced RFID chips have, in particular, built-in cryptographic functions and support strong authentication protocols, that is, authentication of information presented for identification. One of the most popular and widespread devices of this kind on the market is the DST chip. DST is usually a microchip and an antenna coil sealed in a small plastic or glass capsule. It is a passive device, which means that the circuit does not have its own power supply and extracts the energy necessary for the operation of the circuits from the request signals emitted by the reader device.

The attack on DST consists of several inconsistent stages. All stages can be carried out by an amateur who draws additional information from sources on the Internet and is able to assemble this or that electronic device on his knees, which is not characterized by increased complexity. To avoid some problems, the details of the attack have been omitted. So.

First step: Reverse engineering the DST circuit. Usually, at this stage, either the disassembly of the program is used (if its executable code is available), or restoration through the analysis of the operation of the microcircuit itself (by destructive or non-destructive methods). There is also a third, very exotic way - the restoration of the crypto scheme by opening the "black box". In other words, the construction of an equivalent circuit based on the selection and analysis of special sequences supplied to the input and received at the output of the device. By selecting a special type of keys and input vectors-calls, and then analyzing the responses of the chip at the output, it is possible to build an equivalent crypto scheme that gives the same output as DST, with the same input parameters.

The second stage: opening the key of an arbitrary chip. Since it is known that the key length is only 40 bits (the key has been insecure since the beginning of the 90s), it can be opened without any analytical tricks, by a total enumeration of all possible combinations. True, in a purely software implementation on an ordinary (albeit fast) PC, enumeration with this cryptoalgorithm is too slow and takes a long time. Then the hackers “on their knees” assembled a special calculator - a matrix of sixteen FPGA processors (chips with reprogrammable logic), sorting through the keys in parallel. Such a system began to find the secret key of any DST in less than an hour, and this required only two RFID recall to calls of an arbitrary type. Plus, based on the well-known Hellman technique, a balance was calculated between the performance and memory of the calculator, and it was shown that by loading a pre-computed large key table onto the disk of a handheld device like an iPod, the desired key can be found in less than a minute (if instead of a processor general purpose apply a special FPGA, then generally in a few seconds).

The third stage of the study is reduced to "field testing" of the DST simulator, designed on the basis of a laptop and a software-implemented radio transmitter. As a result, with the help of a simulator laptop, I managed to learn how to start a new 2005 Ford Escape (owned by one of the hackers) and fill up gas several times at a gas station with SpeedPass (faking, again, my own payment token).

In the end, however, experts called the demonstrated attack too sophisticated and expensive (because it is much easier and cheaper to steal a car by simply loading it onto a tractor platform). But this is already a matter of subjective assessments, but a constructive approach to the problem is obvious.

You can't get out of wide trousers

There is a lot of talk about the introduction of electronic passports. Information constantly flashes in the press that ES is a universal and perfect means of identifying a person. But that's in theory. In practice, however, there are many problems. The main public complaints about the new passports are the presence of remotely readable RFID chips and the lack of encryption of personal information registered in the memory of the microcircuit. Because of this, the contents of an important identity document becomes available to anyone who has an interest in such information. For the ever-growing number of "identity thefts" new electronic documents provide a truly endless fruitful field. And in general, people prefer to show personal documents only in those cases when they consider it necessary, and not to anyone they meet.

In short, the state, while verbally caring about the safety of citizens, in this case creates only new problems and threats, from which everyone will have to defend themselves. For example, keeping RFID Passport in a shell impervious to electromagnetic waves. Why the authorities preferred the radio frequency form of reading information, and not the obviously safer contact, no one wants to clearly explain. True, the ICAO specifications say that this method was chosen because of the possibility of reading information without the knowledge of the passport holder ... (Did you catch the humor?) For the same reason, apparently, identification by face - much less reliable than the iris, but applicable at much greater distances and again without the knowledge of the owner. In Russia, for the time being, they intend to use "double biometrics", which includes fingerprints.

The new generation as a weapon of mass destruction

In order to calm the dissatisfied and facilitate the introduction of a promising new technology, the industry RFID has developed new chips, the so-called Gen 2, which give out the data written in them only if the reader sends the correct reading password. In addition, the reader can also send another password, "for self-destruction", by accepting which the label erases its contents - for example, when the buyer leaves the store with the paid product.

At first sight, new scheme looks much more attractive than RFID the first generation, especially if we take into account that the data stored on the chip and transmitted over the air is protected by encryption from interception and use by intruders. However, upon closer examination of Gen 2, it turned out that the extreme cheapness of tag chips played a fatal role and, in fact, the protection of the new technology is much weaker than we would like. In particular, durability RFID to the so-called differential analysis of nutrition, with the help of which at one time most of the smart cards available on the market were opened, it turned out to be a schoolgirl's resistance to gang rape. Usually,
RFID tags do not have their own power source, using the radiation energy of the reader device. But when this happens, then each calculation operation in the circuit RFID involuntarily modifies the electromagnetic field around the chip. Thanks to this, using a simple directional antenna, you can track and record the dynamics of power consumption by the chip - in particular, differences in side signals emitted when receiving correct and incorrect password bits.

Analysts with the appropriate skill easily identified peaks on the oscilloscope screen corresponding to incorrect bits, that is, each time starting the procedure again with a slight modification of the wrong bit, it was possible to quickly recover the password that initiated the “suicide” of the chip. After analyzing the tools necessary for such an operation, the researchers came to the conclusion that, in principle, a conventional, specially programmed cell phone is sufficient to automatically calculate the self-destruction password and kill everyone in the radiation zone. RFID.

As known labels RFID are detected by the reader when they enter its coverage area. The reader maintains communication with the tags by switching between channels in the dedicated frequency range (902-928 MHz). It was believed that this was reliable, since in the event of interference, the reader could switch to another frequency. The hacker tests saturated the frequency band used by the tags, preventing them from connecting to the reader. Using frequency hopping does not protect against DoS attacks, since the tags are not able to change the frequency on their own.

From a distance of 1 m, it is possible to break the connection between tags and readers, putting the tag into the "communication error" state. Despite the fact that in the presence of interference, readers can change the frequency within the allocated bandwidth, the tags RFID cannot do this, as they perceive the entire band as one channel.

The small… electronic… enemy?

In connection with all of the above, the desire of some companies to implant RFID tags in people looks at least strange. The owner of such a "black mark" cannot feel safe. But what about electronic passports, are they just as defenseless against bloodthirsty hackers? Fortunately, yes! Recently, on the air of Dutch television, IT specialists broke the access code to information recorded on RFID chips. "Hackers" managed to read the fingerprint, photo and other passport data, according to Engadget. It turned out that the passport code was encrypted based on the date of birth, the date of issue of the passport and its validity period.

Well, that's not all the trouble. According to The New York Times, at a computer conference in Italy, experts said that the RFID system is vulnerable to a virus that, when scanned, can enter a computer. RFID tags contain much more information and are faster for computers to read than traditional barcodes. New tags are becoming more widespread, including being used to track baggage at airports. And this is fraught with danger: terrorists and smugglers can use the flaws in the technology to bypass the scanning systems of the airport, writes The New York Times.

Why, with all the many shortcomings RFID continues to walk the planet and no one is going to give it up? There are two points of view on this issue. The first is that all problems are primarily related to the stupidity, sloppiness and thieving of human material. Here neither RFID v2, nor RFID v10 will not help. Part of problem solving is commonplace administrative measures. Or a lobotomy.

The second point of view ... However, if you do not want to spoil your mood, do not read further. I beg you very much. Live in peace and don't worry about anything.

For those who did not heed the good advice:

• RFID tags no contact or line of sight required; data about you can be obtained without your direct participation.
• RFID tags are read quickly and accurately, which allows you to control a huge number of people at the same time.
• RFID tags can be used even in aggressive environments, through dirt, paint, steam, water, plastic, wood and, of course, human skin and bones.
• passive RFID tags have a virtually unlimited service life, have a low cost.
• RFID tags carry a large amount of information, including the so-called "official".
• RFID tags easy to trace; albeit at a short distance, but exactly where you need it - metro, offices, banks, shops, stops.
• RFID tags can be not only for reading, but also with the recording of a sufficiently large amount of information.

P.S. For a snack. Program RFDump, which seamlessly displays all the metadata written in the label, and even allows you to edit them in a text or hex editor. And why is it necessary, think for yourself.

RFID is a special identification technology that provides users with great opportunities. The most common RFID tags, as well as barcodes, are self-adhesive rfid tags. But if on barcodes all information is stored in a graph. form, data is entered on the label using radio waves.

Application methods

RFID technology (radio frequency identification) is based on the use of electromagnetic radio frequency radiation. RFID is used to account for objects.

RFID tag is a miniature device. Rfid active tags consist of a microchip that stores information and antennas, through which the tag can transmit or receive data. Such an RFID tag has its own power supply, but most tags do not need power (passive).

A unique number and various information are stored in the memory of such a system. If the label falls into the place of registration, this information received by the RFID reader.

For transmission, passive tags use the energy of the reader. Having accumulated energy, the tag starts data transmission. The registration distance for passive tags is 0.05 - 10 meters, depending on the RFID reader and tag device. It should also be taken into account that there are different types of RFID tags.

Where applicable

The scope of application is constantly expanding. This technology is often in demand in industries that require object control and intelligent automation solutions, as well as the ability to work in the most severe conditions, error-free and reliable.

• In RFID-enabled factories, raw materials are accounted for and those are controlled. operations, provide the principles of JIT and FIFO. RFID solutions provide high level reliability and quality stability.
• The RFID warehouse tracks the movement of goods in real time, speeds up the shipment process, increases the reliability of operations and reduces the human factor. RFID solutions provide excellent protection against product theft.
• In the consumer industry merchandise and retail RFID systems track merchandise along the way, from the manufacturer to the counter. The product is delivered to the shelf, not stale in the warehouse and sent to the store, where there is a high demand for it.
• RFID tags have interesting applications - for example, in a library, RFID will help you find books in the store and issue books, and prevent theft. The queues for issuance also disappear. The time for selecting and searching for the desired publication is reduced.
• RFID tags are also used in marking fur coats and other fur products. Each such product is marked with a Control (or special identification) mark with a label embedded in it. At the same time, the cost of rfid tags is mere pennies.

Many areas of business can be improved with new RFID technology. The potential of RFID is huge.

Active and passive rfid tags

Active identifying devices can be characterized by a high reading range, unlike passive ones, as well as the ability to better recognize and read all the necessary data when such a tag moves at high speed. The disadvantage of active tags is the price and bulkiness.

Types of RFIDs

High-frequency RFID tags operating at frequencies of 13.56 MHz;
Ultra-high frequency tags operating at frequencies of 860-960 MHz. This range is used in Europe.

Ways to write to an identifier

1. ReadOnly devices, on which you can write information once, and further change or deletion of information is impossible;
2. WORM devices are RFID radio tags that allow you to write and read all data once. Initially, no information is stored in memory, all data is entered by the user, however, after recording, it is impossible to overwrite or delete information;
3. R / W-devices that allow you to read or write information. This is a more progressive group of devices, since these tags allow you to overwrite and delete even various unnecessary information. Rfid tags are recorded with their own help.

RFID technology tags and applications - used in manufacturing, trade, management and access control systems, document forgery protection systems and other areas.

How to choose an RFID reader?

The choice starts with setting the application goals and understanding the function that the RFID reader performs. And only after that you can buy rfid tags.

• Desktop reader. This type is used for marking books/documents in libraries, personalization when marking fur coats and fur products (using an RFID tag on clothes), to control the authenticity of purchased products. The RFID reader is installed on the table and connected to the computer via USB.
• Mobile RFID reader. These devices are actively used in warehouses, libraries and archives. They are used in work even outdoors, where there is no power. The mobile reader is often used for group search and inventory, identification in the field (repair work, product control).
• portal reader. Its main purpose is an anti-theft function in libraries, warehouses and other facilities. Portal readers are used to better identify vehicles, to account for the movement of people or objects (exhibitions, factories). Also uses the RFID rewritable function.
• Ceiling RFID. Duplicates the function of a classic portal RFID reader, but unlike it, it is installed in place with a wide passage, behind a false ceiling, at objects of cultural value.
• You can also use android (there is a built-in adapter).

RFID key fob

For marking keys, an RFID tag was developed in a plastic case-key fob based on the TwinTag-Mini system.

The TwinTag RFID tag has been designed for permanent use in solutions that require the registration of objects in 3 planes (3D format).

Such a key fob can be used as an identifier and verifier of the electronic signature of a cashier in a bank branch and serviced at a point of sale.

Marking objects:

• Keys.
• Bags.
• Cashier ID.
• Identifier of the on-duty collector.

What is RFID on clothes?

Now stores often sell clothes with chips. These chips are based on markers (RFID), i.e. for the possibility of identification at a distance. Such chips are deliberately placed on clothing so that the consumer does not notice them and continues to wear the clothing with the chip in their daily life.

FID transponders for marking are made on the basis of a silicon chip. Such a chip will increase the service life of the radio tag and provide functional advantages. A clothing RFID tag is a label with a programmable chip containing information about the product.

The size of the antennas has been reduced, which will allow them to be produced with small dimensions. The chip is convenient to use in clothes: fur coats, children's clothing, underwear and other goods. Also used are rfid stickers and rfid labels on clothing and other products.

Thanks to the Gen 3 rfid, the chip in the clothes has an increased memory capacity and is equipped with an additional encryption / generation function serial numbers. This makes rfid tags reliable devices for accounting and protecting goods. In addition, it is possible to make an rfid tag with your own hands (fortunately, this is not very difficult) and store it in everyday clothes.

The RFID chip will allow you to repeatedly add or overwrite data in its memory. RFID tags are easy to read through the packaging, making them easy to place. The RFID tag reading range is several tens of meters.

How to write data to a label

For work, you can use the standard library included in the Arduino, but there is another library written for the module - MFRC522. Both libraries are very convenient, but MFRC522 has more special functions that allow you to shorten the program code.

Where can I buy RFID tags

Based on the selection, you can choose a set of labels for yourself. You can buy it in many online stores. It contains several types of labels for different accounting units. You can test the operation of such equipment with a specific tag in real conditions.

More recently, a fundamentally improved version of theft of funds has been discovered, a new method of stealing money from cards equipped with PayWave and PayPass technologies - criminals intercept signals from such bank cards “over the air” using handicraft readers.

Plastic cards with contactless RFID chips can be used by simply touching them to bank terminal PoS. At the same time, such cards in the PoS terminal are “not rolled” and are not inserted.

Last year, attackers already managed to steal about two million rubles using such hacker devices. In addition, methods have appeared to steal money from credit cards using the latest smartphone models, in which there is a modification of a kind of RFID technology - an NFC device. To withdraw funds from a card, hackers only need to know its full card number and the month/year of service expiration.

PayPass chips are equipped with cards of the international system Mastercard, and chips with the name PayWave are equipped with cards of the Visa payment system. At the same time, both companies allow their contactless technologies to be used both on magnetic stripe cards and on newer cards with a square chip.

The convenience of using the Mastercard-PayPass and Visa-PayWave systems lies in the simplification and acceleration of payments in stores. When making payments up to a thousand rubles with cards with RFID chips, there is no need to sign a cash receipt and enter your PIN code into the PoS terminal.

The meaning of fraudulent schemes is to intercept NFC signals using illegal reader devices. In terms of their technical stuffing, RFID interceptors are highly advanced analogues of conventional contactless POS card terminals with increased functionality that capture and process electromagnetic waves. Such a device is usually equipped with an antenna, a special controller, connectors for extracting information from the reader and pirated computer software.

To read payment data, it will be enough for a fraudster to bring the reader about ten centimeters to the victim’s card.

That is, in the subway or land transport during rush hour, this will be done very easily and imperceptibly. The stolen information is subsequently transferred to other participants, whom the performer often does not even know. And those already produce clones-duplicates of bank cards, which are used to cash out black cash.

The cost of an illegal RFID reader for attacking PayWave and PayPass cards is about a hundred dollars, while the “kulibins” can make them from components that can be ordered on eBae or Aliexpress.

So how can you protect your money from a contactless card hack?

The easiest and most effective way to protect your card from a contactless reader is to carry it along with other non-payment cards. contactless cards, for example, with a transport card "Strelka" or "Troika". When trying to read data, the scammer's device will not be able to copy the information correctly, since the incoming signal will be sent simultaneously from several cards and it will not be processed correctly.

You can purchase a special blocking RFID wallet with read protection. Or there are other cards that you need to put in your wallet next to your credit cards. It is also recommended to enable notification of account balance changes using SMS messages or PUSH notifications. Alternatively, you can further reduce the amount that can be used when paying by card without specifying a PIN.

Also, a significant drawback of NFC readers is the fact that the fraudster needs to place this device almost close to the original bank card, which already provides sufficient protection against reading. Well, if there are several pieces of contactless cards in your purse, then this circumstance will also complicate the criminal intent.

Be careful!

Do you use contactless payments, RFID documents or use your smartphone as a key? All data is at risk - but we will teach you how to avoid hacking.

Contactless technologies: convenient, fast, dangerous

Everyone has plastic cards and documents with microchips based on near field communication (NFC) or with radio frequency tags (RFID). They are equipped with many credit and payment cards, driver's licenses, ID cards, passports, subway tickets and much more.

The contactless form of identification is really convenient - especially if it's Apple Pay or similar. payment system. You don’t even need to apply it to the terminal: you brought it to a distance sufficient for communication, confirmed the payment with your fingerprint, the payment went through.

Despite their convenience, both technologies contain many security holes that allow attackers to obtain sensitive data. In order to steal card data, passwords from a smartphone or copy a pass, you do not need to get close.

Why RFID is dangerous

RFID chips allow you to read data at a distance of up to several meters. All you need to link to the label in the documents is to buy a ready-made device on eBay.

Near-range readers cost about $50, long-range readers cost about a hundred. I will not give links, and delivery to Russia may cause a problem with the special services. But the price allows even a schoolboy to experiment.

After reading, the attacker has a complete electronic copy of all the information of the RFID tag in his hands. With its help, you can make a fake copy, or use other methods - depending on the type of stolen document.

Terminals will treat the copy as the original. Proving otherwise is almost impossible.

Why NFC is dangerous

NFC is actually a variation of RFID, although it has a shorter range of just a few centimeters. But this is only for factory, licensed devices.

Researchers from British University Surrey was able to read NFC data at a distance of up to 80 cm. Spanish hackers even taught Android smartphones to turn into an NFC signal repeater that distributes their own important data.

This approach allows you to make a payment directly through the owner's smartphone. But there are other ways too.

For example, by connecting via NFC with another smartphone or commercially available reader using the application Banking card reader NFC(Android) you can get all the necessary data of the cards used in browser operations. Then it is enough to find a store that allows you to pay without entering a CSV code (and there are still such stores).

How to protect your money and data? Homemade options

In order to completely eliminate unwanted contacts with readers, software tools may not be enough (more on that later).

Therefore, it is worth turning to the old-fashioned methods, and completely cutting off the path to the radiation to your money cards. Two materials are ideal for this - water and metal.


Of course, it is difficult to carry cards in a bag of water. But a piece of ordinary food foil from a roll (suitable from a chocolate bar - but not from a pack of cigarettes) completely blocks RFID and NFC signals.

This is the most efficient and convenient way. It is enough to wrap the card in foil, and take it out only at the time of payment.

Are you afraid of being paranoid? Then ready-made solutions will come in handy.

How do the responsible officials protect the data?

Many Western companies (I have no information about Russian ones) require employees to use special wallets and document covers with the appropriate “Protected from RFID” logo.

Identity Stronghold offers the largest selection of RFID blocking accessories. Part of their range is custom made for the US government for government employees.


You can also find a cheaper option - AliExpress has a wide variety of card cases, wallets with metal inserts. For example, such, or such. You can also simply search by the “NFC protected” tag.

How to prevent data theft

However, it is worth remembering that a metal wallet or card holder for cards does not exclude the possibility of stealing card data.

1. Do not turn on NFC unnecessarily, do not keep it on all the time.

2. The same applies to other wireless interfaces - Bluetooth and Wi-Fi.

3. Check the activity of background processes, if network interfaces are frequently accessed by applications that are not suitable for this - check your smartphone with an antivirus.

4. Don't install apps from unverified sources.