It copied itself into the internal storage, then back to new SD cards.
I wrote out a little text file explaining what had happened and how to remove it.
Never figured out how to tell them about it.
Perhaps there was nothing there and I was mistaken?
I never found out. But I also haven’t noticed anything out of the ordinary with any of my accounts since then. So even if something was up, I think it was not successful.
Your story reminded me of this experience. And also of autorun.inf files on CD-ROMs that would make Windows 95 and later run things. I think at some point in WinXP they disabled auto run of CDs and you had to explicitly choose to run programs that autorun.inf wanted to run.
Only tangentially related to what those GoPro cameras you mention would do with memory cards of course. But a memory nonetheless.
You're a very nice person.
Perhaps this is a weakness, but I'm glad I checked.