According to financial times, data released by Kasperky, a Russian security company, that about 100 banks threatening to hit in the research carried out backing by Interpol , euro pol and agencies in many countries that number of companies investigating.
The attacks were all said to have been mounted by an international criminal gang referred to by the investigator as carbank and said to have representatives in Russia, Ukraine and other parts of Europe, as well as China.
According to financial times, " Kaspersky released that the gang penetrated banks' systems by using a technique called spear phishing in which individual employees are targeted with emails that secretly released malware into a company's system once they are opened"
This code will helps to study the system and activities of official authority to trasfer large amount of cash upto $10m dollar in USA or China in their special account. And sometime, instruction has been setup to dispense cash in atm in certain time.
Reference : financial times 16.02.2015