The agency which oversees standardized testing in Ontario says the failure of its online system last Thursday was due to a cyber attack.
Grade 10 students across the province were given an early chance to pass their literacy test as part of a trial run of the online system, but found themselves staring at frozen web pages instead.
Now the Education Quality and Accountability Office says this was due to an "intentional, malicious and sustained Distributed Denial of Service attack" on the network hosting the test.
This would be the same type of attack that disrupted several major websites like Twitter and Reddit on Friday.
Hackers coordinate an extremely large volume of traffic to target a server, effectively clogging it up.
EQAO says it will continue to investigate how to prevent this from happening again, and has issued another apology to students, schools and other stakeholders.