Microsoft says 8.5M systems hit by CrowdStrike BSOD, releases USB recovery tool

Enlarge / A bad update to CrowdStrike’s Falcon security software crashed millions of Windows PCs last week. (credit: CrowdStrike)

By Monday morning, many of the major disruptions from the flawed CrowdStrike security update late last week had cleared up. Flight delays and cancellations were no longer front-page news, and multiple Starbucks locations near me are taking orders through the app once again.

But the cleanup effort continues. Microsoft estimates that around 8.5 million Windows systems were affected by the issue, which involved a buggy .sys file that was automatically pushed to Windows PCs running the CrowdStrike Falcon security software. Once downloaded, that update caused Windows systems to display the dreaded Blue Screen of Death and enter a boot loop.

“While software updates may occasionally cause disturbances, significant incidents like the CrowdStrike event are infrequent,” wrote Microsoft VP of Enterprise and OS Security David Weston in a blog post. “We currently estimate that CrowdStrike’s update affected 8.5 million Windows devices, or less than one percent of all Windows machines. While the percentage was small, the broad economic and societal impacts reflect the use of CrowdStrike by enterprises that run many critical services.”