Cyber criminals rerouted data from JPMorgan Chase to a major Russian city using a network of computers that are available for hire, according to the bank's own investigators.
The bank, one of the biggest in the world, was subject to a cyber attack in August, which resulted in the successful theft of its data by cyber criminals.
People familiar with the subsequent investigation by the US bank told Bloomberg that there could be a "bulletproof" hosting platform used as the staging ground for the assault, since it has not yet been penetrated by other attackers or law enforcement agencies. It is thought that the network of computers has been used in previous hacking attacks, and is now being used by Eastern European cyber criminals to target banks.
The perpetrators apparently used a network of servers to send commands and withhold their identities while pushing out waves of data through what had been thought of as a highly secure network.
The bank's investigators are not the only team that are trying to trace the computer assault; the FBI and NSA are also working on the case. There have been several reports suggesting that the Russian government may have been involved in the attack as retaliation for US economic sanctions imposed as a result of its support for pro-Russian separatists in Ukraine.
However, a spokesman for President Vladimir Putin dismissed any Russian involvement in the attack, according to Bloomberg.