St Mary’s Star of the Sea College homepage was hit.
The website of a Wollongong Catholic girls' school has been restored after it fell prey to a hacker with a penchant for heavy metal.
The St Mary's Star of the Sea College homepage was taken over late Monday night with unauthorised material including Indonesian emblems, nonsensical letters and messages showing the site had been "executed", and had security flaws.
Acting principal Joanne Hack said the school may have been targeted because it used a particular software.
She said the hacker, whose handle the Mercury will not publish, was most likely interested in notoriety from the feat, and not in the school's goings-on.
"No one really understands the minds of people who do these things," she said.
"The security of the website is something we take seriously but it was a fairly minor incident.
"It was taken care of in a timely way and we thank the people who [pointed it out]."
The hacked page showed the Garuda Pancasila - the national emblem of Indonesia - and the Indonesian flag, set to the song Scream, by American heavy metal band Avenged Sevenfold.
The intrusion delighted some of the school's students, who took to social media to declare it "hilarious".
The school's IT manager removed the hacker's message at about midnight, two hours after it appeared.
The school's page was restored by morning.
Efforts to ensure the security of the site are ongoing.
The hacker is associated with more than 30 previous attacks, according to Hack-DB, the Archive of Hacktivism and Cybercrime.