Conditional logic: compare field values to prevent spam

[Andre_B]

One of my sites apparently caught the attention of spammers. I have a contact form that gets used by them multiple times every day.
I already use conditional logic to show/hide the submit button depending on the result of a simple math question. That doesn’t stop theses spammers.

I noticed that all of these spam mails have in common that the fields ‘first name’ and ‘last name’ have the exact same content. So comparing the content of these 2 fields in a conditional logic would be helpful to resolve the problem. However this is not an available option in GF. In conditional logic I can only show/hide fields based on specific values, not dynamic ones. In other words there’s no option to compare these 2 fields.

Can anyone offer helpful advice?

[Andre_B]

One more detail. All of these spam messages contain a URL in the message field. Is there a way to use this for spam prevention?

[uamv (Joshua Vandercar (Gravity Forms))]

You could use one of the following hooks to check the values upon submission and intercept in some way:

gform_validation
gform_field_validation
gform_entry_is_spam
gform_abort_submission_with_confirmation