Land #11339, Move command_exists? method to Msf::Post::Common

lib/msf/core/post/common.rb

@@ -235,6 +235,20 @@ module Msf::Post::Common
     nil
   end
 
-  private
+  #
+  # Checks if the `cmd` is installed on the system
+  # @return [Boolean]
+  #
+  def command_exists?(cmd)
+    if session.platform == 'windows'
+      # https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/where_1
+      # https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/if
+      cmd_exec("cmd /c where /q #{cmd} & if not errorlevel 1 echo true").to_s.include? 'true'
+    else
+      cmd_exec("command -v #{cmd} && echo true").to_s.include? 'true'
+    end
+  rescue
+    raise "Unable to check if command `#{cmd}' exists"
+  end
 
 end

lib/msf/core/post/linux/system.rb

@@ -215,16 +215,6 @@ module System
     raise 'Unable to check for gcc'
   end
 
-  #
-  # Checks if the `cmd` is installed on the system
-  # @return [Boolean]
-  #
-  def command_exists?(cmd)
-    cmd_exec("command -v #{cmd} && echo true").to_s.include? 'true'
-  rescue
-    raise "Unable to check if command `#{cmd}` exists"
-  end
-
   #
   # Gets the process id(s) of `program`
   # @return [Array]

lib/msf/core/post/solaris/system.rb

@@ -118,16 +118,6 @@ module System
     raise 'Unable to check for gcc'
   end
 
-  #
-  # Checks if the `cmd` is installed on the system
-  # @return [Boolean]
-  #
-  def command_exists?(cmd)
-    cmd_exec("command -v #{cmd} && echo true").to_s.include? 'true'
-  rescue
-    raise "Unable to check if command `#{cmd}` exists"
-  end
-
   #
   # Gets the process id(s) of `program`
   # @return [Array]