WASHINGTON -- The W32.Blaster worm may have contributed to the cascading effect of the Aug. 14 blackout, government and industry experts revealed this week.

On the day of the blackout, Blaster degraded the performance of several communications lines linking key data centers used by utility companies to manage the power grid, the sources confirmed.

"It didn't affect the [control] systems internally, but it most certainly affected the timeliness of the data they were receiving from other networks," said Gary Seifert, a researcher at the U.S. Department of Energy's Idaho National Engineering and Environmental Laboratory in Idaho Falls, referring to flow-control and load-balancing data that's transmitted over public telecommunications networks. "It certainly compounded the problems" relating to the congestion of key communications links used by utilities to coordinate contingency efforts, Seifert added.

The inability of critical control data to be exchanged quickly across the grid could have hampered the operators' ability to prevent the cascading effect of the blackout, he said. Seifert stressed, however, that no one is certain at this point what caused the blackout.

A former Bush administration adviser who has consulted with the U.S. Department of Homeland Security on the power grid issue said the Blaster worm also hampered the ability of utilities in the New York region to restore power in a more timely manner because some of those companies were running Windows-based control systems with Port 135 open - the port through which the worm attacked systems.

Utilities that responded to requests for comment for this article said they weren't adversely affected.

Carol Murphy, vice president of government affairs at the New York Independent System Operator, acknowledged that Blaster affected the utility but said the problem was handled quickly, with no impact on power restoration operations. Joe Petta, a spokesman for Consolidated Edison Company of New York Inc., said there were "absolutely no computer-related problems of any sort that delayed our restoration effort."

The control systems referred to by Seifert, also known as supervisory control and data acquisition (SCADA) systems, are used to manage large industrial operations, such as the natural gas and electric power grids. They're often based on Windows 2000 or XP operating systems and rely on commercial data links, including the Internet and wireless systems, for exchanging information.

Scott Charney, chief security strategist at Microsoft Corp., said that Blaster raised a security and network performance issue for all Microsoft customers and that there was nothing unique about the electric power industry.

Joe Weiss, a control system expert and executive consultant at Cupertino, Calif.-based Kema Consulting Inc., said that in the Blaster case, the power grid fell victim to a worm that attacked the communications infrastructure.

However, the control systems themselves are also at risk.

Current and former energy industry executives, as well as the former Bush administration security adviser, told Computerworld on condition of anonymity that the January outbreak of the Slammer worm affected the real-time control environment of "several" utility companies around the country.

One of those companies was Akron, Ohio-based FirstEnergy Corp. Although FirstEnergy has said publicly that Slammer didn't infect any of the control systems at its Davis-Besse nuclear power plant in Oak Harbor, Ohio, knowledgeable sources said the worm did cause disruptions. However, the plant was in "cold shutdown maintenance mode" and wasn't producing electricity at the time, the sources said. FirstEnergy didn't respond to a request for comment.

"Because Slammer didn't cause any loss of power, it wasn't reported by the utilities that were infected," said an industry executive who had discussions with utility officials.

A spokesperson for the North American Electric Reliability Council (NERC), which is helping to spearhead a task force to study the causes of last month's blackout, declined to comment on the role the Blaster worm may have played. However, a NERC report dated June 20, 2003, shows that the Slammer worm had a significant impact on some utilities.

In one case, a server on a control center LAN running Microsoft's SQL Server wasn't patched, according to the report. "The worm ... apparently [migrated] through the corporate networks until it finally reached the critical SCADA network via a remote computer through a VPN connection," the report states. As a result, "the worm propagated, blocking SCADA traffic."

In a second case documented by Princeton, N.J.-based NERC, a frame-relay-based control network using Asynchronous Transfer Mode "became overwhelmed by the worm, blocking SCADA traffic."