I think you are confusing this with data tx/rx lights for exfil[0]? I've never heard of a tempest attack (that is, revealing the data written via a side channel) on a hard drive light.

[0] Guri et al, LED-it-GO

https://arxiv.org/pdf/1702.06715.pdf

I think it’s this paper I remember that describes it as an “optical tempest” and talks about storage mechanism leakage: http://applied-math.org/acm_optical_tempest.pdf

Yeah it's type II in the Loughry schema. Still unfortunate if you're operating a high security air gapped network, but not squirting out secrets without being compromised first.

It seems almost quaint to worry about this when so much software has web spyware baked into it -- but maybe we need a virtual spyware led that lights up every time something talks to Facebook/Google/etc tracking. The light would be blinking non-stop for many people.