The same Russian military intelligence outfit that hacked the Democrats in 2016 has renewed vigorous US election-related targeting, trying to breach computers at more than 200 organisations including political campaigns and their consultants, Microsoft said Thursday.
The intrusion attempts reflect a stepped up effort to infiltrate the US political establishment, the company said.
"What we've seen is consistent with previous attack patterns that not only target candidates and campaign staffers but also those who they consult on key issues," Tom Burt, a Microsoft vice president, said in a blog post.
UK and European political groups were also probed, he added.
Most of the hacking attempts by Russian, Chinese and Iranian agents were halted by Microsoft security software and the targets notified, he said.
The company would not comment on who may have been successfully hacked or the impact.
Microsoft noted that Chinese state-backed hackers have targeted "high profile individuals associated with the election," including people associated with the Biden campaign.