Jake Williams (below, right), a regular commentator on such events, said in a thread on Twitter that while one possibility was that the US had been carrying out a network attack, it was unlikely.
"I really doubt it (that the US carried out a network attack)," said Williams who now runs his own information security firm, Rendition Infosec.
"It's not like US infrastructure is so much better protected and what goes around comes around. Also, every switch you take down is one more piece of network infrastructure you can't use for other ops. It's not worth the trade IMO."
The Web interface of a switch that was hacked. Graphic courtesy Kaspersky Lab.
Some internal websites, too, were accessed by the attackers and in some cases images of American flags were left, the tech website Motherboard claimed.
Switches at other sites, too, have been compromised, though it appears that a majority of them are Russian and Iranian. Reuters quoted a statement from the Iranian Republic News Agency as saying: "“The attack apparently affected 200,000 router switches across the world in a widespread attack, including 3500 switches in our country.”
Cisco itself had issued a warning about the flaw on Thursday last week through its Talos Intelligence Group. An additional flaw in the client itself had been patched, Talos said, adding that proof-of-concept code was known to be available.
Russian security firm Kaspersky Lab posted some details about the compromises on Friday US time, including an image of the message that the attackers were leaving on the Web interface of the routers they had attacked. The date on the image that Kaspersky posted was 30 March, giving an indication of when the attacks had begun.
Williams said other possibilities were that the attackers were from another country who were carrying out a false flag operation and blaming the US or that these attacks had been carried out by hacktivists.
He said in the former case, "Every nation must realise that they are also vulnerable to the same attacks. Even if you blame it on the US, calling attention to the ease of exploiting the vulnerable switches is probably not in your best interests."
However he said that there was one exception: "It would be a nation that: has a small network footprint relative to Iran and Russia; doesn't care about retaliation against the US; sees an advantage in outages in Iran and Russia; and benefits from cyber conflict between the US and Iran and Russia."
Williams said that while there were countries that met these criteria, they were not many. "However, this attack was not complex so there's not a substantial set of technical obstacles to overcome. E.g. you don't need a Stuxnet or a NotPetya level budget for this attack," he said.
And he added: "Again, any competent nation state would have used these switches for access to internal network assets. Even to 'send a message' this doesn't make sense for a nation state. Occam's Razor says that this was much more likely to be hacktivists."
Motherboard said the alleged hackers had told its reporter, Joseph Cox, that they had carried out the attacks as they were tired of attacks from government-backed hackers on the US and other countries.