In a way, yes. . . however, I just went over the video and the article with a fine-tooth comb and I found this:
"Thunderstrike 2 starts with a local root privilege exploit that can load a kernel module to give it access to raw memory [and] can unlock and rewrite the motherboard boot flash," Hudson says.
They don't tell us right out that the Trojan that's required to invade the original "infection" machine has to be running with ROOT privileges. No normal Mac user ever runs with ROOT priveleges. . . not even an Administrator runs with ROOT privileges. That ROOT user is one level above Administrator. . . and is inactive on a normal Mac. The Administrator can reach ROOT commands by use of the SUDO command (SuperUser DO) for single command lines. Or an Administrator can activate a SuperUser by creating a ROOT account—only one is permitted per machine—by creating a Root user Name and password. Then logging in as that ROOT user.
The likelihood of anyone downloading a TROJAN as a ROOT user are somewhere between zero and nil. . . unless the user is industrial strength stupid and then some.
Using a root privilege exploit means that the victim is running at normal priveleges. The exploit bumps the software up to the root level. The vcitim is not running at root, as you say, nobody does. But it's not impossible to find exploits to get from normal privileges to root, it just adds one more complication to the attack and one more chance for it to fail...
A bug in the latest version of Apple's OS X gives attackers the ability to obtain unfettered root user privileges, a feat that makes it easier to surreptitiously infect Macs with rootkits and other types of persistent malware.
The privilege-escalation bug, which was reported ...
The article about thunderstrike is a little vague. It doesn't come out and say they used a privilege escalation exploit, but it implies that it does.
Ten + years ago, updating a Notion Ink Adam tablet we would causally root our tablet then flash the ROM to allow us to get updates from a web site called Tablet Roms. We were unconcerned about malicious exploits because no one knew of them. How times changed.