A new way of SPAMMING Q&A & recaptch not value because they are HUMAN
 

Hello Everyone ,
There are a new way of spaming in my forums , and it's get famous day by day in the internet , some users come to register in your forum , and they register in about 10-25 forums , after that they put there details (Username&Password) inside a program called Auto Poster , and this program start put there posts over forums , how we can prevent this programs using Iptables or Robots.txt for example ?
Thanks ,
Zi5