Microsoft said on Thursday it had thwarted recent cyberattacks from China, Russia and Iran targeting both Republican and Democratic presidential campaigns.
Microsoft said in a security blog that attackers have been targeting staff from the campaigns of President Donald Trump and his Democratic rival, Joe Biden.
"In recent weeks, Microsoft has detected cyberattacks targeting people and organizations involved in the upcoming presidential election, including unsuccessful attacks on people associated with both the Trump and Biden campaigns," said corporate vice president Tom Burt, according to AFP.
"The activity we are announcing today makes clear that foreign activity groups have stepped up their efforts targeting the 2020 election as had been anticipated, and is consistent with what the US government and others have reported," added Burt.
The attackers have been active against political operatives, think tanks, consultants and political parties in Europe as well, Microsoft said.
It identified a Russia-based group called Strontium which Burt said "has attacked more than 200 organizations" and China-based Zirconium, which he said "has attacked high-profile individuals associated with the election, including people associated with the Joe Biden for President campaign and prominent leaders in the international affairs community."
An Iran-based group dubbed Phosphorus has been targeting personal accounts of people associated with the Trump campaign, Microsoft said.
"The majority of these attacks were detected and stopped by security tools built into our products," Burt added.
"We have directly notified those who were targeted or compromised so they can take action to protect themselves."
US intelligence has found that Russia, among other steps, manipulated social media to sway the 2016 presidential election.
Russia has denied any interference in the 2016 election. While Trump has acknowledged intelligence information indicating that Russia meddled in the 2016 presidential election, he at times has also denounced what he calls the "Russia hoax".
Last year, the White House said Trump warned Moscow against meddling in the 2020 election during a meeting with Russian Foreign Minister Sergey Lavrov.