Potential fix for http://stackoverflow.com/questions/25274125/jsonparsererror-n-unexpected-token-at-alihackeval-request-alihack-c

application.rb

    config.middleware.insert_before ActionDispatch::ParamsParser, ::Rack::Robustness do |g|
      g.no_catch_all
      # you might need to replace this with JSON::ParserError, depending on your Rails configuration
      # or you can catch both...
      g.on(MultiJson::ParseError) { |ex| 400 }
      g.content_type 'text/plain'
      g.body{ |ex| ex.message }
      g.ensure(true) do |ex|
        env['rack.errors'].write(ex.message)
        logger.warn(ex.message)
      end
    end

I changed

logger.warn(ex.message)

to

Rails.logger.warn("RACK ERROR: #{ex.message}")

Thanks for sharing this fix! Initial test would at least get rid of this pesky alihack requests.