From the timeline, Obama had to know the Russian hacking story was fraudulent. From Ray McGovern at antiwar.com:
FBI emails made public in connection with the recent trial of Michael Sussmann show that President Barack Obama was actively encouraging his top security officials to do a number on the Queen of Hearts’ “Sentence First; Verdict Afterwards” in order to help Mrs. Clinton win in 2016.
For those, like me, who wondered how top U.S. law enforcement and security officials felt they had immunity to bend so many of the rules to help Mrs. Clinton, the FBI emails suggest they were given very poor example by the president himself (their conviction that Mrs. Clinton was a shoo-in surely also helped).
Like the manufactured-out-of-whole-cloth story about Trump ties with Russia’s Alfa Bank, there was zero hard evidence to prove that Russia hacked the DNC emails showing that the deck had been stacked steeply against Bernie Sanders.
The recently revealed FBI messages show that Obama ordered Director of Homeland Security Jeh Johnson and Director of National Intelligence James Clapper to press on anyway. So, as with the Alfa Bank caper, they made up the evidence. And the media had a heyday. And Donald Trump won anyway.