This story is incredibly weird, nothing makes sense to me. I can't believe that Bloomberg would willingly report fake news. The fact that they decided to go with it even though Apple and others told them several time using unambiguous language that they were not aware of such an attack means that they must have really trusted their sources since they're effectively saying "Apple is blatantly lying about such a critical issue".
But then why would Apple be lying like that? Seems like it can only backfire for them when the truth is eventually exposed.
Nothing makes sense.
And you have to do all that with a very low power device running from within the port itself. Seems like a very high bar to me, especially when there seems to be so many easier ways to backdoor a motherboard.
But maybe the component is only hosted in the ethernet port but is actually connected to other signals on the motherboard.
As to the beacon itself… DNS is pretty good. Just send an innocuous DNS request to a machine you control (say a NIST time server), if you think an iterative request won't show up on radar. Or send a recursive DNS request along a path you've wiretapped. (I'd be surprised if the NSA doesn't have a feed of all DNS requests to 8.8.8.8.)
Of course you will want to wait to see whether the bugged machine itself sends any such packets out first, to ensure that yours can hide in the noise. Bad idea to send a DNS beacon from a machine that doesn't ever make DNS requests.
Actually on second thought, given the above capabilities, you don't even need to inject packets at all. Just mangle existing DNS queries in such a way that you can identify them in a wiretap. Say, for all DNS requests with a specific hash, mangle the ID field so that it matches some orthogonal hash (and unmangle it on the way back of course). Very unlikely to be noticed by an IPS, and you can statistically determine that machines sending more than expected packets whose ID field matches this second hash are successfully bugged.
Or, why even send packets? Instead, drop all DNS request packets matching some specific hash. They'll eventually get retried with a new server or new ID. Again, statistics applied to wiretapped data can determine whom you've bugged. You don't even need store+forward capability here; just emit noise over the tail of the packet and the switch will drop it for you.
It doesn't mean it's false, it just means Bloomberg already cried wolf and couldn't show it. At this point it feels more like taking shots at Supermicro than professional reporting.