Malware or no malware, ATMs are still hackable

BANGALORE, INDIA: For many years the biggest threat to the customers and owners of ATMs were skimmers – special devices attached to an ATM in order to steal data from bank card magstripes.

But as malicious techniques have evolved, ATMs now have been exposed to more danger. The widespread use of outdated and insecure software, mistakes in network configuration and a lack of physical security for critical parts are also responsible for this.

“From our perspective this is the result of a longtime misbelief, that cybercriminals are only interested in cyberattacks against Internet banking. They are interested in these attacks, but also increasingly see the value in exploiting ATM vulnerabilities, because direct attacks against such devices significantly shortens their route to real money,” said Olga Kochetova, security expert at Kaspersky Lab’s Penetration Testing department.

Software problems
Malware attacks against ATMs are possible due to two main security issues:

All ATMs are PCs running on very old versions of operation systems such as Windows XP. This makes them vulnerable to infection with PC malware and attack via exploits.

In the vast majority of cases, the special software that allows the ATM’s PC to interact with banking infrastructure and hardware units, processing cash and credit cards, is based on XFS standard.

This a rather old and insecure technology specification, originally created in order to standardize ATM software, so that it can work on any equipment regardless of manufacturer.

The problem is that XFS specification requires no authorization for the commands it processes, meaning that any app installed or launched on the ATM can issue commands to any other ATM hardware units, including the card reader and cash dispenser.

Should malware successfully infect an ATM, it receives almost unlimited capabilities in terms of control over that ATM: it can turn the PIN pad and card reader into a “native” skimmer or just give away all the money stored in the ATM, upon a command from its hacker.

Physical security
In many cases, criminals don’t have to use malware to infect the ATM or the network of the bank it’s attached to. That is possible because of the lack of physical security for the ATMs themselves - a very common issue for these devices.

Very often ATMs are constructed and installed in a way that means a third-party can easily gain access to the PC inside the ATM, or to the network cable connecting the machine to the Internet.

By gaining even partial physical access to the ATM, criminals potentially can:
-Install specially programmed microcomputer (a so called black box) inside the ATM, which will give attackers remote access to the ATM;
-Reconnect the ATM to a rogue processing center.

A fake processing center is software that processes payment data and is identical to the bank’s software despite the fact that it doesn’t belong to the bank. Once the ATM is reconnected to a fake processing center, attackers can issue any command they want. And the ATM will obey.

The connection between ATMs and the processing center can be protected in various ways. For example, using a hardware or software VPN, SSL/TLS encryption, a firewall or MAC-authentication, implemented in xDC protocols.

However, these measures are not often implemented. When they are, they are often misconfigured and even vulnerable, something that might only be discovered during an ATM security assessment.

As a result, criminals don’t have to manipulate the hardware, they just exploit insecurities in the network communication between the ATM and the banking infrastructure.

How to stop ATM jackpotting
ATM manufacturers can reduce the risk of attack on cash machines by applying the following measures:

Firstly, it is necessary to revise the XFS standard with an emphasis on safety, and introduce two-factor authentication between devices and legitimate software. This will help reduce the likelihood of unauthorized money withdrawals using trojans and attackers gaining direct control over ATM units.

Secondly, it is necessary to implement “authenticated dispensing” to exclude the possibility of attacks via fake processing centers.

Thirdly, it is necessary to implement cryptographic protection and integrity control over the data transmitted between all hardware units and the PCs inside ATMs.