Regarding the question of attribution to a nation state actor, cybersecurity experts interviewed by BBC Future believed the size of the group required to conduct such an attack would be between 10-20 individuals. Some believed it could be as few as two or three developers, but at least several more individuals would be required to set up and test the attack, and the months they would need would necessitate some sort of HR team as well.

“To actually carry out the full operation,” says Robert M Lee of cybersecurity firm Dragos, “you’ve got management, back office support, healthcare, financials. You’re talking a team of 10 people. But just the malware design and execution, up to five.”

Although attribution to any single actor is too early, the notion that it was cyber criminals seems to be teetering. If the attack was not financially motivated, then what could motivate, and who could resource a startup-sized contingent of actors to pull off such an attack.

“I'm not allergic to the idea that this is nation state anymore,” Sean Sullivan of cyber security firm F-Secure tells BBC Future. “There are compelling details to continue analysing this as a nation state attack. I don't think this theory is garbage.”

For Derevianko, this attack is just the inevitable continuation of something he warned senior Ukrainian officials about three years ago.

“In 2014, I talked to so many people in high levels of government saying that we need to start preparing professionals capable of reacting to really advanced cyber-attacks,” he says. “I told them, if we don’t start preparing now, we’ll be overwhelmed with attacks in three years.”

If Derevianko is right, then, there could be more days like 27 June to come for Ukraine – and if so, the fall-out from these unpredictable infections will spread out into the rest of the world too.

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