The Associated Press said it had obtained a copy of confidential reports from the United Nations Office of Information and Technology, confirming that dozens of servers in the offices of the International Organization in Vienna and Geneva were exposed to piracy.
The internal document from the Office of Information and Technology says that 24 servers were compromised, and 25 servers were considered suspicious, almost all of them at the United Nations offices in Geneva and Vienna.
The agency quoted a UN official, speaking on condition of anonymity, that the attack, which first appeared last summer, appeared complicated, and that the extent of the damage caused by piracy is still unclear, indicating that the United Nations has strengthened its security systems.
He added that the level of sophistication of the penetration was so high that a country could be behind the process, he said.
According to a spokesman for the Human Rights Office, Robert Colville, the Office of the United Nations High Commissioner for Human Rights was breached, but the hackers did not go far in their attempts, stressing that nothing secret was exposed to danger.
According to the agency, the hack appears - at least in the HRO - to have been limited to the so-called active domain, including a staff list and details such as email addresses, but passwords have not been hacked.
Officials said that the main domain that controls all online operations has not been hacked.
Also, Stefan Dujarric, a spokesman for the United Nations Secretary-General, said in an e-mail that the attack "resulted in the destruction of essential infrastructure components" at the organization's offices in Geneva and Vienna, saying it was a "serious" attack.
Dujarric said that the international organization does not have enough information to determine who might be behind the breach, but added that "the methods and tools used in the attack indicate a high level of resources, capacity and design."