Thank you for replying so quickly! I had already tried deactivating the plugins, but it turned out to be the theme that was the problem. A line in functions.php checked if the user was logged in, and if not, a function was activated that blocked various js files from loading, including applyonline-public.js. Removing the line fixed the problem, just in time before the event mentioned above.
Many of the posts were about essay writing. Here’s a blog that seems to have been hit by the same hack:
[ Redacted, please follow the links above and don’t post spammy links like that here. ]
