this post was submitted on 20 Jun 2023
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Lemmy

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PSA: Many Lemmy instances are currently experiencing massive automated sign-ups (bots)! If you run an instance with open sign-ups, please read! (lemm.ee)
submitted 1 year ago* (last edited 1 year ago) by sunaurus@lemm.ee to c/lemmy@lemmy.ml
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Today, a bunch of new instances appeared in the top of the user count list. It appears that these instances are all being bombarded by bot sign-ups.

For now, it seems that the bots are especially targeting instances that have:

  • Open sign-ups
  • No captcha
  • No e-mail verification

I have put together a spreadsheet of some of the most suspicious cases here.

If this is affecting you, I would highly recommend considering one of the following options:

  1. Close sign-ups entirely
  2. Only allow sign-ups with applications
  3. Enable e-mail verification + captcha for sign-ups

Additionally, I would recommend pre-emptively banning as many bot accounts as possible, before they start posting spam!

Please comment below if you have any questions or anything useful to add.

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[โ€“] sunaurus@lemm.ee 1 points 1 year ago (1 children)

How comfortable are you with SQL? You can see all unused verifications in the email_verification table. You should be able to just delete those users from local_user, and then update your user count with the new count of the local_user table in site_aggregates.user (where site_id = 1)

[โ€“] voldern@lemmy.ml 3 points 1 year ago

Thank you for proactively contacting me regarding this @sunaurus@lemm.ee. I've had this issue on my https://feddi.no instance, but I have added a captcha and registration applications now. Hopefully it will alleviate some of the problem.

All of the bots accounts seems to have a number in their email so I manually looked through the list of users in email_verification that contained numbers in the email to look for false positives:

select * from email_verification where email ~ '[0-9]+';

before running

delete from local_user where id in (select local_user_id from email_verification);

to delete the users.

By suggestion from @sunaurus@lemm.ee I updated site_aggregates to reflect the new users count on the instance:

UPDATE site_aggregates SET users = (SELECT count(*) FROM local_user) WHERE site_id = 1;.