A massive cyberattack that crippled the Canvas online learning platform as finals were getting underway at many universities could leave them scrambling for as long as a month — and expose the education software giant to major legal and financial fallout, cybersecurity experts told The Post. The breach of the popular learning platform, owned by Instructure, disrupted coursework, exams and student communications at universities and school systems across the US and beyond after hackers linked to the notorious ShinyHunters group said they infiltrated the system and exposed sensitive user data. The group targeted almost 9,000 schools and accessed data from over 275 million people, according to a ransom letter shared online . Instructure said names, email addresses, student ID numbers and private messages were compromised, though it added that there was no evidence passwords, Social Security numbers or financial data were exposed.…