Hackers use Rootkit to Zero in on Bank Networks for ATM Money Theft

Digital criminals are tapping into a novel rootkit to steal funds from bank ATM machines. The threat actor’s rootkit zeroes in on Oracle Solaris systems. The overarching aim of the attack is to tap into ATMs to switch networks and execute illegal withdrawals of large sums of cash at banks with fake cards.

Who Originally Identified the Hack?

The rootkit zero attacks were identified by the digital security specialist Mandiant. Mandiant is continuing to track the cluster. The cluster in question has the name “UNC2891”. Some of the hackers’ strategies for accessing ATMs are similar to those employed in the cluster referred to as “UNC1945”.  

Mandiant released a report detailing the hack earlier this past week. Take a look at the report or read through the remainder of this content. You will likely be motivated to implement the latest technological safeguards to protect your valuable computers, servers, and software.

Is the Intrusion Primarily Limited to one Threat Group?

In short, no. There is a significant overlap between the UNCs noted above, meaning the digital infiltration is not solely the result of one threat group.  

How is the Attack Performed?

The digital infiltration is somewhat complex as it contains a considerable OPSEC degree, making use of private as well as public malware, scripts, and utilities. These tools are used to eliminate the trail of evidence and mitigate cyber security specialists’ defenses against the attack. The hackers responsible for ATM money theft use the CAKETAP rootkit that hides network connections, files, and processes.

When Were the Attacks First Identified?

The AMT hacks have occurred for several years. However, the illegal activity was not identified until recently. The exact date of the attacks’ discovery has not yet been revealed.

Why is the Attack Successful?

Mandiant successfully recovered forensic memory data from a targeted ATM’s server switch. The digital security specialist indicated a kernel rootkit variant containing unique features empowered it to intercept both PIN messages for verification. Card data empowered the hackers to use the stolen information to perform illegal money withdrawals from multiple ATMs.

The success of the hackers behind the money theft is partially attributable to the use of TINYSHELL and SLAPSTICK backdoors, each of which is attributed to the cluster of UNC1945. These backdoors allow for ongoing remote access to shell execution, mission-critical systems, and file transfers through rlogin, SSH, and telnet.  

The TINYSHELL’s backdoors are configured with the use of distinct values that appear to be actual services that provide utility. Such backdoor values are not glaringly obvious, meaning digital security specialists are likely to skip right over them without stopping to perform in-depth analysis. Examples of those backdoor values include Linux at daemon and service cache daemon.

What is the Role of Malware and Utilities in the Attack?

The hack contains unique attack chains that use extensive utilities that are publicly available and employ malware. Examples include MIGLOGCLEANER, a utility that removes specific log strings from Linux. WIPERIGHT is another ELF utility that eliminates log entries relating to Linux user systems.  

WINGCRACK is a utility that sorts through encoded content created through WINGHOOK. WINGHOOK is best described as a Linux keylogger that obtains information within an encoded format. Finally, STEELHOUND serves as an in-memory dropper variant that encrypts binaries and decrypts embedded payloads.