On October 2, 2018, an alert was issued by US-CERT, the Department of Homeland Security, the Department of the Treasury, and the FBI. According to this new alert, Hidden Cobra (the U.S. government’s code name for Lazarus) has been conducting “FASTCash” attacks, stealing money from Automated Teller Machines (ATMs) from banks in Asia and Africa since at least 2016.
Lazarus is a very active attack group involved in both cyber crime and espionage. The group was initially known for its espionage operations and a number of high-profile disruptive attacks, including the 2014 attack on Sony Pictures. More recently, Lazarus has also become involved in financially motivated attacks, including an USD 81 million theft from the Bangladesh Central Bank and the WannaCry ransomware.
Following US-CERT's report, Symantec’s research uncovered the key component used in the group's recent wave of financial attacks. The operation, known as “FASTCash”, has enabled Lazarus to fraudulently empty ATMs of cash. To make the fraudulent withdrawals, Lazarus first breaches targeted banks’ networks and compromises the switch application servers handling ATM transactions.
Once these servers are compromised, previously unknown malware (Trojan.Fastcash) is deployed. This malware in turn intercepts fraudulent Lazarus cash withdrawal requests and sends fake approval responses, allowing the attackers to steal cash from ATMs.
According to the U.S. government alert, one incident in 2017 saw cash withdrawn simultaneously from ATMs in over 30 different countries. In another major incident in 2018, cash was taken from ATMs in 23 separate countries. To date, the Lazarus FASTCash operation is estimated to have stolen tens of millions of dollars.
In order to permit their fraudulent withdrawals from ATMs, the attackers inject a malicious Advanced Interactive eXecutive (AIX) executable into a running, legitimate process on the switch application server of a financial transaction network, in this case a network handling ATM transactions. The malicious executable contains logic to construct fraudulent ISO 8583 messages. ISO 8583 is the standard for financial transaction messaging. The purpose of this executable has not been previously documented. It was previously believed that the attackers used scripts to manipulate legitimate software on the server into enabling the fraudulent activity.