Russian Intelligence Hackers Are Back, Microsoft Warns, Aiming at Democrats and Republicans

The Biden campaign said that 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 that it was preparing for the inevitable onslaught of attacks in the coming weeks. While the campaign did not confirm the company’s reporting, it has taken issue with the director of national intelligence’s assessment, issued several weeks ago, that Chinese leaders prefer Mr. Biden over Mr. Trump.

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

So far, Microsoft officials said they found no evidence that hacking efforts this year were successful, but corporate officials noted that they had limited vision into Russia’s overall operations. They cannot say definitively that no materials were stolen, or what Russia’s motivations may be. That, they said, was the role of U.S. intelligence officials.

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.

In a statement, Christopher Krebs, who directs the Cybersecurity and Infrastructure Security Agency at the Department of Homeland Security, said, “We are aware that Microsoft detected attempts to compromise email accounts of people and organizations associated with the upcoming election.”

Mr. Krebs noted that “none are involved in maintaining or operating voting infrastructure and there was no identified impact on election systems.” He also said that the company’s “announcement is consistent with earlier statements by the intelligence community on a range of malicious cyberactivities targeting the 2020 campaign and reinforces that this is an all-of-nation effort to defend democracy.”

Mr. Krebs, who was a Microsoft executive before joining the Trump administration, said his agency was releasing on Thursday “guidance for improving cyberdefenses against account compromise attacks.”