cross-posted from: https://lemmy.cat/post/6385
It is currently possible, through Lemmy's API, to create accounts automatically and without limit if verification by email address or captcha is not activated. I'd advise you to activate one or both of them NOW!
After registering x number of accounts (currently I could do thousands), all you have to do is list all the existing communities for each of the account to publishes one new post per community, or more. I'll leave you to picture the mess.
(I apologise to the administrators of sh.itjust.works, I should have done the test with my own server.)
I was playing a bit with the API today and yea it might even be a bit too easy at the moment. You can easily use that army of Lemmy bots to upvote all your posts.
We should probably make it very clear in tutorials and setup guides that no email verification is insecure and leaves your instance open to bots.
Stupid of me, I hadn't thought about upvotes, but it's clear that this is perhaps the most "quiet" and dangerous type of abuse.