The Society for Worldwide Interbank Financial Telecommunication has James Bond-level security at the facilities it uses to move millions of bank-payment orders around the world every day.

Visitors to a Swift operations center in Culpeper, Va., say their car trunks were inspected upon arrival by armed guards, who used mirrors to check under the chassis. Security inside included a fingerprint scan, a test for chemical weapons and an iris scanner in the most restricted areas.

“It’s like Fort Knox,” says Mohan Murali, chief executive of Axletree Solutions Inc., which helps banks and companies connect to Swift.

That isn’t where the thieves hit. In the past year, a spate of cyberattacks has penetrated banks along Swift’s less-defended perimeter, shaking confidence in the dominant network used by banks for cross-border transactions. While Swift diligently locked down that network’s core, customers were left mostly responsible for their own security, creating an opportunity for hackers.

Targets included banks in India, Vietnam, Ecuador and Bangladesh. Thieves made off with a total of about $90 million from Bangladesh’s central bank and a commercial bank in Ecuador. The other cyberattacks were unsuccessful.