Choose fallback if stage encoding fail

lib/msf/core/payload/stager.rb

@@ -16,7 +16,8 @@ module Msf::Payload::Stager
       [
         Msf::OptBool.new("EnableStageEncoding", [ false, "Encode the second stage payload", false ]),
         Msf::OptString.new("StageEncoder", [ false, "Encoder to use if EnableStageEncoding is set", nil ]),
-        Msf::OptString.new("StageEncoderSaveRegisters", [ false, "Additional registers to preserve in the staged payload if EnableStageEncoding is set", "" ])
+        Msf::OptString.new("StageEncoderSaveRegisters", [ false, "Additional registers to preserve in the staged payload if EnableStageEncoding is set", "" ]),
+        Msf::OptBool.new("FallbackToNoStageEncoding", [ false, "If encoders choosen in StageEncoder are not compatible to stage encoding fallback to no encoding otherwise fallback to automatic selected one", true ])
       ], Msf::Payload::Stager)
 
   end
@@ -100,7 +101,7 @@ module Msf::Payload::Stager
   # @return [Boolean]
   def encode_stage?
     # Convert to string in case it hasn't been normalized
-    !!(datastore['EnableStageEncoding'].to_s == "true" || !datastore["StageEncoder"].blank?)
+    datastore['EnableStageEncoding'] == "true" || !datastore["StageEncoder"].to_s.empty?
   end
 
   #
@@ -236,7 +237,14 @@ module Msf::Payload::Stager
         'ForceSaveRegisters' => true,
         'ForceEncode'        => true)
       if (encp.encoder == nil)
-        print_warning("#{encoder} didn't succeed")
+        print_warning("Encoder #{encoder} did not succeed")
+        if !datastore['FallbackToNoStageEncoding']
+          print_warning("Fallback to automatic StageEncoder selection")
+          encoder = nil
+          redo
+        else
+          print_warning("Fallback to no encoder")
+        end
       else
         print_status("Encoded stage with #{encp.encoder.refname}")
       end