A cyber attack hit several universities and schools in the US, Canada and Australia, causing chaos, confusion and major disruptions amid the high stakes end-of-year season.

The hacking group ShinyHunters reportedly claimed responsibility for the attack, which caused the academic software Canvas used by thousands of schools and universities to go offline this week.

By late Thursday, the company Instructure, which owns Canvas, posted an update on its website saying that Canvas was "available for most users", but some universities were still reporting outages on Friday.

The cyber attacks targeted universities and schools across the globe, affecting an estimated 9,000 institutions.

The University of Sydney told students on Friday "Canvas was unavailable" and instructed students not to attempt to log in.

"We are one of approximately 9000 institutions around the world that are impacted by this outage, and we are still waiting for advice from Instructure," the university wrote in an announcement on its website.

The outage affected students' coursework and examinations, the university said, acknowledging "how disruptive this is at a critical time in the semester".

Penn State University wrote in a message to students on Thursday that "no one has access" to Canvas, adding that a "resolution" was unlikely to arrive "within the next 24 hours". The university cancelled some exams scheduled for Thursday and Friday.

In an update on Thursday evening, the University of British Columbia in Vancouver informed students that Canvas was "unavailable due to a cyber breach of its parent company Instructure", and advised them to log out immediately.

The University of Toronto also reported it was impacted by the breach, saying that "multiple universities were affected".

Students at the University of California Los Angeles struggled to submit assignments online through the Canvas platform, and the University of Chicago, in Illinois, temporarily disabled its Canvas page after reports that it was targeted.

The Chicago Maroon, the university-led newspaper, posted a screenshot of a message from ShinyHunters that appeared to be seeking a ransom.

The message encouraged the university to contact the hacking group privately "to negotiate a settlement" and avoiding "the release of their data".

Screen shots show the targeted threats from the group began on Sunday, with deadlines given on Thursday and 12 May, Luke Connolly, a threat analyst at the cyber security firm Emisoft, told the Associated Press.

He said discussions regarding extortion payments could be ongoing.

Cyber attacks on Thursday came the same day that the top US Senate Democrat, Chuck Schumer, sent a letter to the Trump administration urging for more defence against cyber risks in the age of rapidly developing AI.

The Department of Homeland Security - the agency that helps ward off against cyber attacks - "must immediately help states and localities", Schumer wrote.

"Before Americans are hit with outages, disruptions, and attacks that could put lives and livelihoods at risk," he continued.

(BBC News)