The CIA on Friday admitted that cyberattacks have caused at least one power outage affecting multiple cities outside the United States.

Alan Paller, director of research at the SANS Institute, said that CIA senior analyst Tom Donahue confirmed that online attackers had caused at least one blackout. The disclosure was made at a New Orleans security conference Friday attended by international government officials, engineers, and security managers from North American energy companies and utilities.

Paller said that Donahue presented him with a written statement that read, "We have information, from multiple regions outside the United States, of cyber intrusions into utilities, followed by extortion demands. We suspect, but cannot confirm, that some of these attackers had the benefit of inside knowledge. We have information that cyberattacks have been used to disrupt power equipment in several regions outside the United States. In at least one case, the disruption caused a power outage affecting multiple cities. We do not know who executed these attacks or why, but all involved intrusions through the Internet."

Information about which foreign cities were affected by the outage and other information related to the attack was not mentioned and is unlikely to be forthcoming, said Paller.

A call to the CIA asking for further comment was not immediately returned.

Donahue said that the CIA had thoroughly weighed the pros and cons of making this information public, according to Paller.

The prospect of cyberattacks crippling multicity regions appears to have prompted the government to make this information public. The issue "went from 'we should be concerned about to this' to 'this is something we should fix now,' " said Paller. "That's why, I think, the government decided to disclose this."

The delegates at the meeting were sharing data about cyberattacks on critical utilities and resources, and methods of attack mitigation. One topic of discussion was the new SCADA and Control Systems Survival Kit, a document of best practices for SCADA systems. SCADA stands for Supervisory Control And Data Acquisition and refers to devices that control critical infrastructure like power generators, traffic signals, and dams. The security of SCADA systems has been a concern among federal officials for years.

In San Francisco on Thursday, following a private screening of the new documentary The New Face Of Cybercrime, Howard Schmidt, a former Microsoft executive and government cybersecurity adviser, mentioned ongoing concerns about the vulnerabilities of SCADA systems and noted that 85% of the U.S. critical infrastructure is controlled by the private sector. "No one should be minimizing this issue," he said.

Citing two Government Accountability Office reports on SCADA security, Paller said that people have been adding wireless and Windows to SCADA systems without really thinking about security. "They're gotten radically unsafe," he said.