The attack was allegedly carried out by European, Russian, and Chinese hackers, who used malicious software to penetrate the banking systems – via sending e-mails to employees. After the hacking the bank’s internal computers used by the employees, hackers found out what employees were responsible for cash transfers or ATMs, and installed a remote access tool: a program that can take screenshots from employees’ computers,
"This is likely the most sophisticated attack the world has seen to date in terms of the tactics and methods that cybercriminals have used to remain covert," Doggett,said.Due to nondisclosure agreements with the banks Kaspersky have not reveled the banks names that were hit. But the officials at the White House and the F.B.I. have been briefed on the findings, and they are coordinating an investigation.