BORYSPIL, Ukraine — When departure information disappeared from Kiev airport’s website after a recent cyberattack, employees trained a camera on the departure board and broadcast it to YouTube. When government servers were switched off, officials posted updates to Facebook.

And with the disruption continuing, office workers have turned to Gmail to keep their businesses going.

As Ukraine’s digital infrastructure shuddered under the weight of the cyberattack, Silicon Valley firms played an outsize role in keeping information flowing, an illustration both of their vast reach and their unofficial role as a kind of emergency backup system.

Google’s mail service has kept the lights on at some firms after their email servers went down, while Facebook is credited as a crucial platform for digital first responders.

“Our war room, nationwide, migrated to Facebook,” said Andrey Chigarkin, the chief information security officer at a Kiev-based gaming firm and active participant in the early hours of the online response. “All the news — bad, good — was coming through Facebook.”

Facebook has a relatively low take up in Ukraine, counting between 8 to 9 million monthly active users compared to 10 to 15 million in Poland, a neighbor of roughly the same size, according to figures provided by analytics firm SocialBakers.

But it’s still a powerful medium there and is credited with being an accelerant for the protest movement that toppled the Russia-friendly leader Viktor Yanukovych in 2014.

Today, government agencies regularly post official statements to their Facebook walls and press officers eschew email to chat with journalists over Facebook Messenger.

“Facebook in Ukraine is a big thing,” said Dmytro Shymkiv, the deputy head of Ukraine’s presidential administration and a former director of Microsoft Ukraine.

Shymkiv was among the many officials to post updates about the outbreak as it happened (to Facebook, naturally.) In an interview at his office, he said that “the cloud” — a marketing term for the pool of sometimes free computing power offered by the likes of Google, Facebook, Microsoft, Amazon and many others — provided the safety and redundancy that many businesses in Ukraine lacked.

“It’s a global backup,” he said, adding that, as a former tech executive, he knew that Silicon Valley firms put an “enormous focus on the security of the cloud services.”

Private businesses and even government offices are still relying at least in part on Silicon Valley firms’ email and chat services, mainly as a substitute for downed mail servers.