Researchers from IBM Trusteer have uncovered a massive fraud operation that leveraged a network of mobile device emulators to steal millions of dollars from online bank accounts in a few days.
The cybercriminals used about 20 mobile device emulators to mimic the phone of over 16,000 customers whose mobile bank accounts had been compromised.
According to the experts, this is one of the largest banking fraud operations ever seen, the hackers managed to steal millions of dollars from financial institutions in Europe and the US.
Experts also reported that in a single and separate case, cybercriminals spoofed 8,173 devices with a single emulator.
“This is the work of a professional and organized gang that uses an infrastructure of mobile device emulators to set up thousands of spoofed devices that accessed thousands of compromised accounts.” reads the report published by the researchers. “In each instance, a set of mobile device identifiers was used to spoof an actual account holder’s device, likely ones that were previously infected by malware or collected via phishing pages.”
The threat actors obtained login credentials for online bank accounts using a mobile malware botnet or scraping phishing logs, then used them to finalize fraudulent transactions at scale.
The threat actors entered usernames and passwords into banking apps running on the emulators and then made fraudulent transactions.
Crooks used the emulators to bypass security measures implemented by banks to detect fraudulent transactions. They used device identifiers corresponding to each compromised account holder and spoofed GPS locations previously associated with the device. The attackers have obtained the device IDs from the infected devices were also able to bypass multi-factor authentication by accessing SMS messages.
The hackers developed an application for feeding the emulators with device specifications that were picked up automatically from a database of compromised device logs, providing speed and accuracy of all parameters to the emulator (i.e. brand, OS version, IMEI, and bootloader).
“Additionally, the automation matched the device with the account holder’s username and password for access to their bank account.” continues the analsysis.
“When a compromised device operated from a specific country, the emulator spoofed the GPS location. From there, it connected to the account through a matching virtual private network (VPN) service. The attackers used a mix of legitimate tools available publicly (used mostly in testing) and customized applications likely created for the operation.”
The crooks managed to automate the process of accessing accounts, starting the transaction, capturing the OTP code sent via SMS, finalize the illicit transactions.
IBM researchers pointed out that crooks would retire the spoofed device that was involved in a successful transaction, and replace it with a new device. The attackers also cycled through devices when they were rejected by the anti-fraud systems used by the banks.
The threat actors behind this fraud operation intercepted communications between the spoofed devices and the banks’ application servers to monitor the progress of operations in real-time.
“It is likely that those behind it are an organized group with access to skilled technical developers of mobile malware and those versed in fraud and money laundering. These types of characteristics are typical for gangs from the desktop malware realms, such as those operating TrickBot or the gang known as Evil Corp.” concludes IBM Trusteer.
“In subsequent attacks using the same tactics, we were able to see evolution and lessons learned when the attackers evidently fixed errors from past attacks. This is indicative of an ongoing operation that is perfecting the process of mobile banking fraud.”
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(SecurityAffairs – hacking, fraud operation)