U.S. school districts affected by the recent cyberattack on edtech giant PowerSchool have told TechCrunch that hackers accessed “all” of their historical student and teacher data stored in their student information systems. PowerSchool, whose school records software is used to support more than 50 million students across the United States, was hit by an intrusion in December that compromised the company’s customer support portal with stolen credentials, allowing access to reams of personal data ...