It is clear that the government relied on assumptions made by a source external to the US intelligence services. According to the source the Russian state had been involved in hacking and stealing data from various servers and that data was sent to Wikileaks.
A private cyber security company recruited by the Democratic National Committee writes a draft report and removes some elements because it is worried that the FBI might discover something. And this is the main proof of Moscow’s role in this hacking? Of course, sceptics could ask why a private cyber security company conducted the investigation. Why wasn’t it the FBI? Faith can lift mountains, transform beliefs, policies, countries. No need for a prophet or a miracle. All you need is a private company.