Fix a "undefined method to_sym" bug

If something is undetectable, the value may be empty, which triggers
a undefined method error because the regex always assumes there is
something. So instead of +, we use *.

lib/msf/core/exploit/browser/server.rb

@@ -149,7 +149,7 @@ module Msf
         update_profile(target_profile, :source, 'script')
         raw = Rex::Text.decode_base64(Rex::Text.uri_decode(request.body))
         raw.split('&').each do |item|
-          k, v = item.scan(/(\w+)=(.+)/).flatten
+          k, v = item.scan(/(\w+)=(.*)/).flatten
           update_profile(target_profile, k.to_sym, v)
         end