CrowdStrike gives initial report on how last week's global computer outage happened

Cybersecurity firm CrowdStrike said Wednesday a bug in a software update caused the worldwide disruptions to banks, retailers and airlines last week.

CrowdStrike said the update was meant to gather new data about potential threats. But an undetected bug in the update caused certain Windows operating systems to crash to the infamous "Blue Screen of Death."

In total, about 8.5 million machines were affected — but the true impacts were much wider because of all the other systems that relied on those computers. Hospitals, government agencies, TV stations, banks and airlines all ground to at least temporary halts.

As of Wednesday, some businesses had still not fully recovered from the downtime.

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CrowdStrike says it's changed some of its procedures to lessen the risk of future crashes. It says it will stagger updates instead of deploying them globally at the same time, and do more internal testing on updates to hopefully find bugs before they make it into the wild.

Regulators are now taking a close look at CrowdStrike and the outage. Department of Transportation Secretary Pete Buttigieg on Wednesday announced a federal investigation against Delta Air Lines, and lawmakers say they want to hear testimony from CrowdStrike CEO George Kurtz about what happened.

“All too often these days, a single glitch results in a system-wide outage, affecting industries from healthcare and airlines to banks and auto-dealers,” said U.S. Federal Trade Commission chair Lina Khan on Sunday. “Millions of people and businesses pay the price. These incidents reveal how concentration can create fragile systems."