The report relies on inference. Because there is a virus, the virus took the emails to Russia.
That the CIA, FBI and NSA accepted and amplified the leap to conclusion (source of Wikileaks DNC leak is "the Russians") is troublesome, too.
By now, the false conclusion is treated as an article of faith by the press and by Congressional investigators. Questioning an article of faith is dismissed as kookery and unfounded.
Have you read the report? It doesn't even do that. It points to several different types of "viruses" (actually malware, but the report uses the word "virus") as potentially being present and then goes onto say "well, if the servers were patched properly this wouldn't have happened. Oh by the way, here's the list of patches to apply!"
The entire "report" is a fucking joke and was written by some half-assed dumb-ass intern working in a closet somewhere. To try and claim that report as "analysis" of a hacking incident strains all credulity!