Need helping figuring out how spam cases is entering our org.

Job ID: 31186392

Budget: $30 – $250 CAD

I have several web to case forms on 4 different sites.
Spam cases are entering our org for webforms that have not been made publicly available. I need help identifying how these spam cases are being created and would like block and stop spam cases from created.
Related categories: Salesforce.com Salesforce Lightning