Hackers have never stopped trying to interfere in USA politics, they've only gotten smarter about covering their tracks, researchers from Microsoft disclosed on Thursday.
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.
Attempts by foreign adversaries to disrupt the November 3 presidential election echo the efforts by Russian Federation in 2016 to meddle in the campaign on Trump's behalf.
Subscribe to the CNET Now newsletter for our editors' picks of the most important stories of the day. The party said the hacking attempts were unsuccessful.
Microsoft believes Fancy Bear is behind the attacks based on an analysis of the group's hacking techniques and network infrastructure, one of the sources said. So far, Strontium has targeted more than 200 organizations, including political campaigns and other groups affiliated with Republican and Democratic officials.
The attacks included phishing, a hacking method which seeks to trick users into disclosing passwords, as well as other efforts to infiltrate SKDK's network, the three sources said.
"In recent weeks, Microsoft has detected cyber attacks targeting people and organisations 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.
The attempts appear to be part of a broader increase in affecting USA political campaigns and related groups, the company said. "We have known from the beginning of our campaign that we would be subject to such attacks and we are prepared for them".
The consensus among cybersecurity experts is that Russian interference is the most serious.
Foreign groups used tactics including rotating IP addresses to disguise attacks, web bugs planted in purchased domain names and phishing, in an effort to harvest log-in credentials and gain information on targeted individuals and organizations.
An Iran-based group dubbed Phosphorus has been targeting personal accounts of people associated with the Trump campaign, Microsoft said.
"As President Trump's re-election campaign, we are a large target, so it is not surprising to see malicious activity directed at the campaign or our staff", said the Trump campaign's deputy national press secretary, Thea McDonald. "We take cybersecurity very seriously and do not publicly comment on our efforts".
Officially, neither SKDK, Microsoft, or the Biden campaign have commented on the Reuters report.
But more recently, the Trump administration has sought to stifle the release of intelligence findings linked to election meddling, particularly with regard to Russian Federation.
The Microsoft post shows that Russian military intelligence continues to look for election-related targets, undeterred by U.S. indictments, sanctions and other measures, Mr Hultquist said.