The goal of the cyber attack at the International Monetary Fund was to install software that would give a nation state a digital insider presence on the network, a cybersecurity expert who has worked for the IMF and World Bank told Reuters on Saturday.

It was a targeted attack, said Tom Kellerman, who understands the network architecture at both international financial institutions and who serves on the board of a group known as the International Cyber Security Protection Alliance.

The code was developed and released for this purpose, he said.

(Reporting by Jim Finkle; Editing by Peter Cooney)