Hi Ram,
Thanks for taking the time to submit this suggestion.
Entering the business of providing IP reputation and web application firewall services is not the direction we envisage for WHMCS.
There are a number of established services which can potentially help with this already; Cloudflare, CloudFront, mod_security, Immunify365 are the ones which spring to mind immediately. Perhaps one of those can help meet your website hardening needs?