NEW YORK - Russian intelligence is hacking campaign officials from both parties, while China is also growing more adept at targeting campaign workers, according to the New York Times.

But contrary to Trump administration warnings, Beijing is mostly targeting Biden campaign officials, Microsoft warned.

Microsoft’s findings come just two weeks after the director of national intelligence, John Ratcliffe, declared that he would no longer let intelligence agencies give detailed, in-person briefings about election interference to Congress. He said the restrictions were because of leaks.

The Russian military intelligence unit that attacked the Democratic National Committee four years ago is back with a series of new, more stealthy hacks aimed at campaign staff, consultants and think tanks associated with both Democrats and Republicans.

That warning was issued on Thursday by the Microsoft Corporation, in an assessment that is far more detailed than any yet made public by American intelligence agencies.

The findings come one day after a government whistle-blower claimed that officials at the White House and the Department of Homeland Security suppressed intelligence concerning Russia’s continuing interference because it “made the president look bad,” and instructed government analysts to instead focus on interference by China and Iran.

Microsoft did find that Chinese and Iranian hackers have been active — but often not in the way that President Trump and his aides have suggested.

Contrary to an assessment by the director of national intelligence last month that said China preferred former Vice President Joseph R. Biden Jr. win the election, Microsoft found that Chinese hackers have been attacking the private email accounts of Mr. Biden’s campaign staff, along with a range of other prominent individuals in academia and the national security establishment, including groups like the Atlantic Council and the Stimson Center.

Notably, only one of the Chinese targets detected by Microsoft was affiliated with Mr. Trump, a former administration official whom Microsoft declined to name.

The Biden campaign said it was “aware of reports from Microsoft that a foreign actor has made unsuccessful attempts to access the noncampaign email accounts of individuals affiliated with the campaign,” and was preparing for the inevitable onslaught of attacks in the coming weeks.

The Microsoft investigation also concluded that hackers related to Russia’s G.R.U., the military intelligence unit that oversaw the “hack and leak” campaigns in 2016 that made emails from Hillary Clinton’s campaign public, is going to new lengths to hide its tracks. It is routing some of its attacks through Tor, a service that conceals the attackers’ whereabouts and identity, which slowed the effort to identify the hackers.