Something weird happened today. After restoring my Time Machine backup and only updating iWork and Safari, I've forgotten to disable automatic OS and security updates.
When I woke my MacBook Air 2,1 this evening, it took a very long time to log me in. System Version is now 17G3025, albeit it doesn't show an installed SU 2018-002 in App Store or System Profiler. But it does show 'macOS Installer Notification' and 'MRTConfigData' installs one day after the Safari update. I didn't issue those and they were never shown in App Store. SU 2018-002 is no longer available for me in App Store.
WiFi was broken again, but I just had to reinstall IO80211.kext from 10.10.5. Everything else seems fine for now, had issues with Finder sidebar only showing one item on the last attempt. And kernel panics every other minute.
I'm not d100% sure, but it looks like my firmware was updated, too! I'm pretty positive it read along the lines of '1.34f8' just like the SMC version - not sure about the exact numbers, but the formatting was the same - now it is MBA21.0075.B03. I don't trust my memory here, maybe it was like this all the time. Should have taken a screenshot.
Since 1989, this is by far the strangest update I've ever experienced, even on supported machines (Mac Pro 5,1).
[doublepost=1542562094][/doublepost]Try a different USB stick.