The group warned it would release all stolen data if schools did not make contact by May 12.
The message included a link to a list of schools ShinyHunters claims to have breached through Canvas.
Many universities across the United States, including Columbia University, Rutgers, Princeton, Kent State, Harvard and Georgetown, issued statements alerting students to a cyberattack affecting institutions nationwide.
School districts in the US states of California, Florida, Georgia, Oklahoma, Oregon, Nevada, North Carolina, Tennessee, Utah, and Virginia have also been affected.
Stanford University said Canvas was “currently unavailable due to an issue being experienced by the vendor,” adding that Instructure had recently disclosed a nationwide information security issue it said had been contained.
But a further outage was now affecting Canvas customers including Stanford and “numerous other educational institutions nationwide,” the university added.
Instructure said the stolen data in the original breach included personal details such as names, email addresses and student ID numbers, along with private messages exchanged between users.
