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Anti-Card Skimming Technology For ATM Systems

Nanjing Yuantuo Tech : 11 October, 2010  (Special Report)
Banking System security specialist surveys existing ATM security technology and provides alternative method of preventing card-skimming
Anti-Card Skimming Technology For ATM Systems
Since ATMs have different models and shapes, it is difficult for ordinary cardholders to distinguish between normal card slots and exceptional ones. Therefore, they always fall into criminals' traps and ATM crimes also keep increasing. Installing a skimmer on the card slot has become the most common form of ATM crime. Although video surveillance systems have been installed on most ATMs, these can be only used for ex-post evidence collection and it does not have any effect on pre-warning and preventing crimes. Faced with complex ATM card-use environments and due to inherent pitfalls of the video surveillance system itself, it can't provide prompt and effective pre-warning and prevention.

The basic function of the security system is to detect crimes in time and prevent them, but the facts have proved again and again that single ATM video surveillance systems can't curb rampant bank card crimes effectively. The current situation has requested urgently that the ATM security field should turn traditional passive prevention into proactive security.

Stealing bank card numbers and PINs to clone bank cards has become the modus operandi covering the largest proportion of ATM crimes. Other interferences, like posting false notes, are also used to clone bank cards. From technical level, cloning banks card needs two basic elements. One is bank card number (not printing card number on the card face) and the other is the PIN. Neither is dispensable. As long as one of them is protected, cloning risks can be eliminated. Since there are various kinds of methods to steal PINs, for example, installing video cameras or false PIN pads. It is difficult to take a unified technical preventative measure. Bank card number is the most basic element of cloning bank card and the only way to obtain it lies on the card slot (the card access system in self service banking has been canceled). Therefore, criminals all install password theft equipment on the card slot. From the perspective of pre-warning, the safety of the bank card can be guaranteed if the card slot is well-guarded.

Currently, a few solutions can be used to detect whether the card slot is exceptional (for example, installing skimmers and password theft equipment). Comparative analyses of different solutions are as follows:

1 Light judgement: utilize the infrared light reflection principle. Drill some holes around the card reader and the infrared light will be emitted through the holes form internal part of the self service equipment. When criminal installs the other device on the card reader, it will block some holes. In this way, it can judge whether there is an illegal device installed on the ATM.
The disadvantage of this method is that it must drill holes on the ATM, which will break the original structure of the ATM. In addition, if there are some exceptional objects (such as dusts) blocking the holes or the light environment changes, it will cause high false alarm rate. If the skimmer is installed bypass the holes, it will cause alarm omissions.
Therefore, this solution is not feasible in the real world.

2 Electromagnetic field judgement: use the magnetic field strength sensor or electromagnetic field strong sensing device to detect the electricity and magnetic field changes around the ATM card reader and then compare the change situations to the normal ones. If any exception occurs, it indicates that there is a card theft device installed on the card reader.
This method uses short-range detection technology, which also needs to drill installation holes on the ATM and change ATM's original structure. If the ATM has a metal shell, the detection device must be installed outside and thus it itself will become a potential safety hazard. Besides, theoretically speaking, as long as there is an object that can change magnetic field strength, there will be false alarms. If you turn down the detection sensitivity, it will cause alarm omissions, moreover, it is very difficult to grasp the scale of sensitivity adjusting.
Therefore, this solution is not feasible in the real world either.

3. Use image processing technology to analyze images on the ATM card reader and find out features. Compare the images to the ones on the original card reader and if there is an exception, it indicates that a skimmer is installed on the ATM.

This method is sensitive to environmental illumination, which has high requirements on image definition. Once these conditions can't be satisfied, it will bring about high false alarm rate. However, its most serious weakness is that the video camera used at current can only capture flat images which have no anti-counterfeiting function. If the installed skimmer has the same appearance and color as the original card reader, it is impossible to tell them apart from video images and thus serious alarm omissions will generate.

Since the existing surveillance video cameras all have the inherent features of flat images, so it is difficult to use flat image analysis to solve the recognition problem of skimmers and the actual results at home and abroad are not good, either.

All bank card password theft crimes have a common feature, which is to install skimmers on ATMs. Any installation means that physical thickness of some important parts (card slot, PIN pad) has been changed. Use high-precision laser ranging sensor to monitor the changes of spatial height of these sensitive parts in real time and thus it can judge whether there is a skimmer installed on the card slot. Moreover, it will raise the alarm, pre-warning and voice prompt as well as taking on-site pictures during the installation process and thus it can help prevent crimes in time and win more time for arresting criminals.


First of all, use high-precision laser ranging system to do a multi-point range on the card reader and its surrounding area and then store the measuring results as the reference value. In the normal operation, repeat to measure the card readers on self service devices according to a certain cycle and pre-set conditions and compare the received measured distance value to the stored reference value. If the measured distance value is within the alarm distance parameter value, it shall keep the current status; if the measured distance value is over the alarm distance parameter value, it indicates that the physical status around the card reader has been changed and it shall send alarm signal to the control module and then gather the continuous alarm time. If the continuous alarm time is over the set alarm parameter, the control module will emit pre-warning commander, pre-warning alarm signal, voice prompt and on-site picture capturing via the IOT module. Actions like normal card inserting won't cause false alarm.

The anti-skimming system from Yuantuo uses the phased laser ranging module to achieve high-precision laser multi-point ranging and it can form a laser protection net around the cars reader. Since the device is installed in front of the self service equipment within a certain distance, it is easy to achieve good concealment. Moreover, it does not need to break the self service equipment and its installation place is not fixed, which means that it can be installed away from the ATM within distance between 0.05M—30M. Besides, the laser light path of the equipment has a wide detection range and it isn't easy to be affected by the environment and electromagnetic interference and thus false alarms and omission problems of traditional equipment can be solved effectively.

This system specially sets an IOT module which can monitor the status of the card slot on the ATM in each outlet bank through central networking in real time and report the exceptional situations to the center in time. Meanwhile, it can be connected with the SMS alarm module to send SMS alarm to relevant staff and SMS alarm platform.

In a word, anti skimming system that based on the new-generation pre-warning and prevention principles is the effective supplement and development of traditional video monitoring system. It largely increases bank's prevention ability, changes the traditional single video surveillance thoughts and makes full use of various kinds of sensors to establish a perfect system with advanced pre-warning, on-site deterrence, safe device and crime controlling as well as power projection. It has a great significance on fighting against ATM crimes, protecting cardholders' benefits and maintaining bank's social image as well as guaranteeing financial order.
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