Bangladesh's central bank was vulnerable to hackers because it did not have a firewall and used second-hand, $10 switches to network computers connected to the SWIFT global payment network, an investigator into one of the world's biggest cyber heists says.

It seems, had the Federal Reserve Bank of New York been cautious about financial transactions, the hacked funds of Bangladesh Bank could easily be stopped from being transferred to banks in the Philippines and Sri Lanka, and from there to the pockets of the hackers.

Cyber thieves might have found it easier to break into the Bangladesh Bank system after its local area network (LAN) was connected with its SWIFT operation, according to central bankers and investigators.

Two engineers of SWIFT have come to Bangladesh to review its servers with the central bank -- 38 days after a band of hackers breached the payment system in an attempt to steal about $1 billion.