The hackers are said to have targeted more than 200 organizations, most of which were linked to Trump and Biden ahead of the presidential election in early November.
"It is clear that foreign groups have stepped up their efforts towards the 2020 election, which has been predicted and is in line with what the US government and others have reported," Microsoft wrote in a blog post.
Investigations by Special Prosecutor Robert Mueller and the Senate Intelligence Committee have shown that Russia influenced the US presidential election in 2016. US intelligence agencies have warned that foreign governments may try to influence the presidential election in November this year.
Among other things, Microsoft points out the infamous Russian hacker group Strontium, with links to the Russian intelligence service, as responsible. Strontium is also suspected of having tried to influence the 2016 presidential election.