Big tech companies are under pressure to ramp up security for 2020 US elections and others globally

A hacking group that appears to be linked to the Iranian government attempted to intrude into a U.S. presidential contender's campaign but did not succeed, Microsoft Corp said on Friday.

Microsoft saw "significant" cyber activity by the group which also targeted current and former U.S. government officials, journalists covering global politics and prominent Iranians living outside Iran, the company said in a blog post.

In a 30-day period between August and September, the group, dubbed "Phosphorous" by the company, made more than 2,700 attempts to identify consumer email accounts belonging to specific customers and then attacked 241 of those accounts.

"Four accounts were compromised as a result of these attempts; these four accounts were not associated with the U.S. presidential campaign or current and former U.S. government officials," the blog post said.

"Microsoft has notified the customers related to these investigations and threats and has worked as requested with those whose accounts were compromised to secure them."

Microsoft did not identify the election campaign whose network was targeted by Phosphorous hackers. Nineteen Democrats are seeking their party's nomination to run against Republican President Donald Trump in the November 2020 election.

Hacking to interfere in elections has become a concern for governments, especially since U.S intelligence agencies concluded that Russia ran a hacking and propaganda operation to disrupt the American democratic process in 2016 to help then-candidate Trump become president. Moscow has denied any meddling.

Tensions between the United States and Iran have risen since May 2018 when Trump withdrew from a 2015 international nuclear accord with Tehran that put limits on its nuclear program in exchange for easing of sanctions. Trump has since reinstated U.S. sanctions, putting increased pressure on the Iranian economy, including its oil trade.

The Iranian government did not issue any immediate comment through state-run media on Microsoft's statement.

Phosphorus is also known as APT 35, Charming Kitten, and Ajax Security Team, according to Microsoft.

The Redmond, Washington-based company said Phosphorous used information gathered from researching their targets or other means to game password reset or account recovery features and attempt to take over some targeted accounts.

The attacks were not technically sophisticated, the blog said. Hackers tried to use a significant amount of personal information to attack targets, it said.

"This effort suggests Phosphorous is highly motivated and willing to invest significant time and resources engaging in research and other means of information gathering," the blog post said.

Microsoft has been tracking Phosphorus since 2013 and said in March that it had received a court order to take control of 99 websites the group used to execute attacks.

A computer network used by 2016 Democratic presidential candidate Hillary Clinton's campaign was hacked in a cyberattack on Democratic Party political organizations in that U.S. election.

Big tech companies are under pressure to ramp up security for next year's U.S. elections and others around the world.

Companies including Facebook Inc, Alphabet Inc's Google, Microsoft and Twitter Inc met with U.S. intelligence agencies earlier in September to discuss security strategies.

Microsoft had said in a blog post in July that about 10,000 customers were targeted or compromised by nation-state attacks in the past year. Most of the activity originated from hackers in three countries: Iran, North Korea and Russia, the company said.