Fix DRDoS mixin to handle empty responses

Author: jhart-r7

lib/msf/core/auxiliary/drdos.rb

@@ -46,7 +46,11 @@ def prove_amplification(response_map)
       bandwidth_amplification = total_size - request.size
       if bandwidth_amplification > 0
         vulnerable = true
-        multiplier = total_size / request.size
+        if request.size == 0
+          multiplier = total_size
+        else
+          multiplier = total_size / request.size
+        end
         this_proof += "a #{multiplier}x, #{bandwidth_amplification}-byte bandwidth amplification"
       else
         this_proof += 'no bandwidth amplification'

spec/lib/msf/core/auxiliary/drdos_spec.rb

@@ -34,5 +34,11 @@
       result, _ = subject.prove_amplification(map)
       expect(result).to be false
     end
+
+    it 'should handle empty responses' do
+      map = { '' => [ 'foo' ] }
+      result, _ = subject.prove_amplification(map)
+      expect(result).to be true
+    end
   end
 end