The unfolding crisis will push to the front of Biden’s agenda when he takes office on Jan. 20.
Officials did not say which agencies or infrastructure had been breached or what information taken in a March attack.
Bryan Ware of the Department of Homeland Security is leaving government after being asked to resign.
The gaffe came in 2017 -- just weeks after Giuliani had been named President Donald Trump's cybersecurity adviser.
Arjen Kamphuis was last seen two weeks ago.
Various government agencies have been at work to ensure safe voting, but Trump himself rarely talks about the issue.
The move marks the first time the United States has publicly accused Moscow of hacking into American energy infrastructure.
Matthew Masterson, currently chairman of the U.S. Election Assistance Commission, is being removed from his post by Paul Ryan.
A cyber attack disrupted Friday’s opening ceremony, but "all issues were resolved and recovered" by Saturday, Games organizers said.
"Can we get a charger in here, please?!"