The International Monetary Fund is investigating a suspected attack on its computers, a potentially sensitive breach of a system that centralizes confidential information about the finances of most of the world’s countries. Fund officials would provide few details about the cyberattack, which occurred as the agency is overseeing financial rescue programs in several European nations that have required painful social spending cuts, and is pressing nations such as China on economic reform. There was “an incident of intrusion into our IT system.