Posts Tagged: ONS

Dec 10

Cable: No Cyber Attack in Brazilian ’09 Blackout

The Nov. 2009 blackout that plunged millions of Brazilians into darkness for up to six hours was not the result of cyber saboteurs, but instead an unusual confluence of independent factors that conspired to cause a cascading power failure, according to a classified cable from the U.S. embassy in Brazil.

The communication, one of roughly 250,000 to be published by, provides perhaps the most detailed explanation yet of what may have caused the widespread outage, which severed power to 18 of Brazil’s 27 states, cutting electricity for up to 60 million Brazilians for periods ranging from 20 minutes to six hours. The Nov. 2009 outage was notable because it came just three days after a CBS news magazine 60 Minutes report about a much more severe two-day outage in 2007 that cited unnamed sources claiming that the blackout was triggered by hackers targeting electric control systems.

Reports from and other news publications quickly challenged that 60 Minutes segment, pointing to previous investigations that suggested a variety of factors contributed to the 2007 incident, including poorly-maintained electrical insulators. But when another outage hit Brazil three days after the CBS report, the coincidence led to more speculation about whether hackers were once again involved.

The cable relates information shared by executives and engineers from Brazil’s National Operator of the Interconnected Power System (ONS), which “further ruled out the possibility of hackers because, following some acknowledged interferences in past years, [the Government of Brazil] has closed the system to only a small group of authorized operators, separated the transmission control system from other systems, and installed filters.” From the cable:

“Coimbra confirmed that the ONS system is a CLAN network [classified local area network] using its own wires carried above the electricity wires. Oliveira pointed out that even if someone had managed to gain access to the system, a voice command is required to disrupt transmission. Coimbra said that while sabotage could have caused the outages, this type of disruption would have been deadly, and investigators would have found physical evidence, including the body of the perpetrator. He also noted that any internal attempts by system employees to disrupt the system would have been easily BRASILIA 00001383 003 OF 005 traceable, a fact known to anyone with access to the system.”

So what did cause the blackout? The cable suggests there were a range of contributing factors and some very bad timing:

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