and those behind it gain access to digital files of several u.s. government agencies including the treasury the justice and state departments it was a huge deal at the time the u.s. said that they suspected that moscow was behind the attack but investigations were still going on but now the finger of blame is being firmly pointed at russia but again with this caveat that the u.s. has high confidence quote unquote in the assessment that russia is to blame but no concrete evidence has been put forward and russia has all this time of course denied any involvement whatsoever. and it is and it's also isn't it a sharp change in tone that we've heard from america over the last couple of days because you know if you going back to then the walls talk of a summit between america and russia well exactly just 2 days ago on tuesday biden and putin spoke by phone or biden once again said that his goal was to build a stable and predictable relationship with russia and at the time he also proposed a summit between the 2 leaders to take place and a 3rd country and the biden administration has said that that summit that meeting is vital to stop the ex escalation of t

and those behind it gain access to digital files of so. well u.s. government agencies including the treasury the justice and state departments it was a huge deal at the time the u.s. said that they suspected that moscow was behind the attack but investigations were still going on but now the finger of blame is being firmly pointed out russia but again with this caveat that the u.s. has high confidence quote unquote in the assessment that russia is to blame but no concrete evidence has been put forward and russia has all this time of course denied any involvement whatsoever and it's also isn't it shop change in tone that we've heard from america over the last couple of days because you know if you going back to then the walls talk of a summit between america and russia well exactly just 2 days ago on tuesday biden and putin spoke by phone or biden once again said that his goal was to build a stable and predictable relationship with russia and at the time he also proposed a summit between the 2 leaders to take place and a 3rd country and the biden administration has said that that summit that meeting is vital to stop the ex escalation of tensions betwe

software called solar wind was hacked and the hackers gained access to digital files of several us federal agencies including the treasury justice and state department this was a huge deal at the time and then the u.s. said that they suspected that russia was behind the attack but investigations were still ongoing but this document officially points the finger at russia without giving any sort of concrete evidence and of course russia has asked to see some sort of real proof that they could possibly be behind it and they have denied all accusations up until this but again the caveat there was that there was high confidence in the assessment that russia was behind that attack but there's no concrete evidence and of course me mentioned the phone call that took place before just before these sanctions were and there's also talk of a face to face meeting between putin to exactly just 2 days ago on tuesday biden and putin spoke by phone they touched on a number of topics but among that the u.s. president floated the proposition of having a summit between the 2 leaders in the 3rd 3rd country where they could get together and move towards once again saying

the attack last year was known as solarwinds. it allowed russian government hackers access to at least 18,000 government and private computer networks including the departments of state, justice, treasuryxperts say the hack continues to this day. bill whitaker has the story for "60 minutes." >> i think from a software engineering perspective it's probably fair to say that this is the largest and most sophisticated attack the world has ever seen. >> reporter: brad smith is president of microsoft. he learned about the hack after the presidential election this past november. by that time the stealthy intruders had spread throughout the tech giant's computer network and stolen some of its proprietary source code used to build its software products. more alarming, how the hackers got in. piggybacking on a piece of third-party software used to connect, manage and monitor computer networks. what makes this so momentous? >> one of the really disconcerting aspects of this attack was the widespread and indiscriminate nature of it. what this attacker did was identify network management software from a company called solarwinds. they installed malware into an update for a solarwinds product. when