"Der Spiegel reporters were able to find mobile phone numbers, email addresses and even some passwords belonging to [America's] top officials."
Just wildly speculating here but it feels like if you combine this with the Signal "linked devices" attack, you get a scenario where [someone] might have pwned #MikeWaltz's phone and used their access to publicly embarrass him by adding #JeffreyGoldberg to the group chat.
@cryptadamist But why should Russia or China do this. The Trump Administration is the best that could happen to them.
@tbachner yeah i agree that is the weak point in this line of speculation. also why would they burn their access to Waltz's phone? they definitely would not do that.
but maybe someone else would...
@tbachner i edited my post slightly
@cryptadamist This is an interesting bit of speculation though. I want to believe that it was the old slip of the thumb that added his number (same way I got added to a family group chat where they openly discussed my Christmas presents one year), but some other actor basically being like “see what we could do?” is definitely in the realm of possibility.