It's a valid hypothesis and not crazy at all. If this were random I'd expect totally random cities, not the three most economically significant.
It might not be covert economic warfare, but more of a covert demonstration whose audience is intended to be the US government. "We have lots of dangerous 0-days, and there's a lot more where these came from." In that case public credit would never be claimed.
It reminds me of how GitHub kept getting DDOSed for no reason. Turns out GitHub was a popular demo target for vendors of DDOS botnets to show their power.
Edit: could be exactly that... a demo of wares by a black market vendor of 0-days for a potential buyer.
Edit #1: a non-malicious explanation might be a vendor pushing out a bad software update to something.
It might not be covert economic warfare, but more of a covert demonstration whose audience is intended to be the US government. "We have lots of dangerous 0-days, and there's a lot more where these came from." In that case public credit would never be claimed.
It reminds me of how GitHub kept getting DDOSed for no reason. Turns out GitHub was a popular demo target for vendors of DDOS botnets to show their power.
Edit: could be exactly that... a demo of wares by a black market vendor of 0-days for a potential buyer.
Edit #1: a non-malicious explanation might be a vendor pushing out a bad software update to something.