Do initial fix

Author: jvazquez-r7

lib/msf/core/exploit/file_dropper.rb

@@ -3,6 +3,9 @@
 module Msf
 module Exploit::FileDropper
 
+  include Msf::Post::Common
+  include Msf::Post::File
+
   def initialize(info = {})
     super
 
@@ -22,6 +25,8 @@ def initialize(info = {})
   def on_new_session(session)
     super
 
+    @session = session
+
     if session.type == "meterpreter"
       session.core.use("stdapi") unless session.ext.aliases.include?("stdapi")
     end
@@ -32,6 +37,8 @@ def on_new_session(session)
 
     @dropped_files.delete_if do |file|
       win_file = file.gsub("/", "\\\\")
+      exists_before = check_file(file, win_file)
+
       if session.type == "meterpreter"
         begin
           # Meterpreter should do this automatically as part of
@@ -41,10 +48,9 @@ def on_new_session(session)
             session.shell_command_token(%Q|attrib.exe -r #{win_file}|)
           end
           session.fs.file.rm(file)
-          print_good("Deleted #{file}")
-          true
+          file_deleted?(file, win_file, exists_before)
         rescue ::Rex::Post::Meterpreter::RequestError
-          false
+          return false
         end
       else
         win_cmds = [
@@ -59,8 +65,7 @@ def on_new_session(session)
         # succeed. Doing it this way saves us an extra round-trip.
         # Trick shared by @mihi42
         session.shell_command_token("rm -f \"#{file}\" >/dev/null ; echo ' & #{win_cmds.join(" & ")} & echo \" ' >/dev/null")
-        print_good("Deleted #{file}")
-        true
+        file_deleted?(file, win_file, exists_before)
       end
     end
   end
@@ -125,6 +130,39 @@ def cleanup
       print_warning("This exploit may require manual cleanup of '#{f}' on the target")
     end
 
+    private
+
+    def session
+      @session
+    end
+
+    alias :client :session
+
+    def check_file(file, win_file)
+      if session.platform =~ /win/
+        res = file_exist?(win_file)
+      else
+        res = file_exist?(file)
+      end
+
+      res
+    end
+
+    def file_deleted?(file, win_file, exists_before)
+      if exists_before
+        if check_file(file, win_file)
+          print_error("Unable to delete #{file}")
+          false
+        else
+          print_good("Deleted #{file}")
+          true
+        end
+      end
+
+      print_warning("Tried to delete #{file}, unknown result")
+      true
+    end
+
   end
 end
 end