BulkBan lets you ban lists of usernames in bulk from a pastebin.
It's very easy to use.
A list of usernames should look like this:
// You can include comments like this
After you have the list uploaded to Pastebin just use:
and it will ban every player on that list using "/ban <username> <reason>".Code (Text):/bulkban <pastebinUrl> <banReason>
Note that the default vanilla command "/ban" doesn't allow banning offline players, you'll need a banning plugin for this to work with offline accounts.
There's only 1 permission you'll need:
Code (Text):bulkban.admin Allows you to use the main command
Lists of spambot / cracked accounts to ban: