Another round of crappy journalism. It's not obscure, it's not a CPU feature but a platform feature, and there are plenty of out-of-band communication channels out there, this isn't the only one. On top of that, this was already published two DEF CONs ago.

You can exfil data and even do practival bi-directional communication over: SOL, IPMI, ASF, MT's ARC CPU via injected firmware and then via TCP/IP. Any of them will work. Add vendor-specific firmware addons on top of that (i.e. Broadcom tends to have exploitable firmware in their NIC controllers)

Most of them are in a vulnerable state by default because the technology was supposed to be 'easy' and 'user friendly', but 'users' don't even know what they are, and most deployments are done by the WinTel horde that doesn't actually know anything outside the Microsoft framework. (and thus leave the defaults as-is)

I probably posted something similar on https://news.ycombinator.com/item?id=11913379

Is it bad? Yes. Is it new? No. Is it ever reported on correctly? Also no.