Land rapid7#2075, Powershell Improvements

Author: Meatballs1

lib/msf/core/exploit/powershell.rb

@@ -1084,17 +1084,18 @@ def self.to_mem_aspx(framework, code, exeopts={})
   end
 
   def self.to_win32pe_psh_net(framework, code, opts={})
-    hash_sub = {}
-    hash_sub[:var_code] 		= Rex::Text.rand_text_alpha(rand(8)+8)
-    hash_sub[:var_kernel32] 	= Rex::Text.rand_text_alpha(rand(8)+8)
-    hash_sub[:var_baseaddr] 	= Rex::Text.rand_text_alpha(rand(8)+8)
-    hash_sub[:var_threadHandle] 	= Rex::Text.rand_text_alpha(rand(8)+8)
-    hash_sub[:var_output] 		= Rex::Text.rand_text_alpha(rand(8)+8)
-    hash_sub[:var_temp] 		= Rex::Text.rand_text_alpha(rand(8)+8)
-    hash_sub[:var_codeProvider] 	= Rex::Text.rand_text_alpha(rand(8)+8)
-    hash_sub[:var_compileParams] 	= Rex::Text.rand_text_alpha(rand(8)+8)
-    hash_sub[:var_syscode] 		= Rex::Text.rand_text_alpha(rand(8)+8)
+    rig = Rex::RandomIdentifierGenerator.new()
+    rig.init_var(:var_code)
+    rig.init_var(:var_kernel32)
+    rig.init_var(:var_baseaddr)
+    rig.init_var(:var_threadHandle)
+    rig.init_var(:var_output)
+    rig.init_var(:var_codeProvider)
+    rig.init_var(:var_compileParams)
+    rig.init_var(:var_syscode)
+    rig.init_var(:var_temp)
 
+    hash_sub = rig.to_h
     hash_sub[:b64shellcode] = Rex::Text.encode_base64(code)
 
     return read_replace_script_template("to_mem_dotnet.ps1.template", hash_sub).gsub(/(?<!\r)\n/, "\r\n")

lib/msf/util/exe.rb

@@ -0,0 +1,62 @@
+# -*- coding: binary -*-
+
+require 'rex/exploitation/powershell/output'
+require 'rex/exploitation/powershell/parser'
+require 'rex/exploitation/powershell/obfu'
+require 'rex/exploitation/powershell/param'
+require 'rex/exploitation/powershell/function'
+require 'rex/exploitation/powershell/script'
+require 'rex/exploitation/powershell/psh_methods'
+
+module Rex
+  module Exploitation
+    module Powershell
+      #
+      # Reads script into a PowershellScript
+      #
+      # @param script_path [String] Path to the Script File
+      #
+      # @return [Script] Powershell Script object
+      def self.read_script(script_path)
+        Rex::Exploitation::Powershell::Script.new(script_path)
+      end
+
+      #
+      # Insert substitutions into the powershell script
+      # If script is a path to a file then read the file
+      # otherwise treat it as the contents of a file
+      #
+      # @param script [String] Script file or path to script
+      # @param subs [Array] Substitutions to insert
+      #
+      # @return [String] Modified script file
+      def self.make_subs(script, subs)
+        if ::File.file?(script)
+          script = ::File.read(script)
+        end
+
+        subs.each do |set|
+          script.gsub!(set[0], set[1])
+        end
+
+        script
+      end
+
+      #
+      # Return an array of substitutions for use in make_subs
+      #
+      # @param subs [String] A ; seperated list of substitutions
+      #
+      # @return [Array] An array of substitutions
+      def self.process_subs(subs)
+        return [] if subs.nil? or subs.empty?
+        new_subs = []
+        subs.split(';').each do |set|
+          new_subs << set.split(',', 2)
+        end
+
+        new_subs
+      end
+    end
+  end
+end

lib/rex/exploitation/powershell.rb

@@ -0,0 +1,63 @@
+# -*- coding: binary -*-
+
+module Rex
+module Exploitation
+module Powershell
+  class Function
+    FUNCTION_REGEX = Regexp.new(/\[(\w+\[\])\]\$(\w+)\s?=|\[(\w+)\]\$(\w+)\s?=|\[(\w+\[\])\]\s+?\$(\w+)\s+=|\[(\w+)\]\s+\$(\w+)\s?=/i)
+    PARAMETER_REGEX = Regexp.new(/param\s+\(|param\(/im)
+    attr_accessor :code, :name, :params
+
+    include Output
+    include Parser
+    include Obfu
+
+    def initialize(name, code)
+      @name = name
+      @code = code
+      populate_params
+    end
+
+    #
+    # To String
+    #
+    # @return [String] Powershell function
+    def to_s
+      "function #{name} #{code}"
+    end
+
+    #
+    # Identify the parameters from the code and
+    # store as Param in @params
+    #
+    def populate_params
+      @params = []
+      start = code.index(PARAMETER_REGEX)
+      return unless start
+      # Get start of our block
+      idx = scan_with_index('(', code[start..-1]).first.last + start
+      pclause = block_extract(idx)
+
+      matches = pclause.scan(FUNCTION_REGEX)
+
+      # Ignore assignment, create params with class and variable names
+      matches.each do |param|
+        klass = nil
+        name = nil
+        param.each do |value|
+          if value
+            if klass
+              name = value
+              @params << Param.new(klass, name)
+              break
+            else
+              klass = value
+            end
+          end
+        end
+      end
+    end
+  end
+end
+end
+end

lib/rex/exploitation/powershell/function.rb

@@ -0,0 +1,98 @@
+# -*- coding: binary -*-
+
+require 'rex/text'
+
+module Rex
+module Exploitation
+module Powershell
+  module Obfu
+    MULTI_LINE_COMMENTS_REGEX = Regexp.new(/<#(.*?)#>/m)
+    SINGLE_LINE_COMMENTS_REGEX = Regexp.new(/^\s*#(?!.*region)(.*$)/i)
+    WINDOWS_EOL_REGEX = Regexp.new(/[\r\n]+/)
+    UNIX_EOL_REGEX = Regexp.new(/[\n]+/)
+    WHITESPACE_REGEX = Regexp.new(/\s+/)
+    EMPTY_LINE_REGEX = Regexp.new(/^$|^\s+$/)
+
+    #
+    # Remove comments
+    #
+    # @return [String] code without comments
+    def strip_comments
+      # Multi line
+      code.gsub!(MULTI_LINE_COMMENTS_REGEX, '')
+      # Single line
+      code.gsub!(SINGLE_LINE_COMMENTS_REGEX, '')
+
+      code
+    end
+
+    #
+    # Remove empty lines
+    #
+    # @return [String] code without empty lines
+    def strip_empty_lines
+      # Windows EOL
+      code.gsub!(WINDOWS_EOL_REGEX, "\r\n")
+      # UNIX EOL
+      code.gsub!(UNIX_EOL_REGEX, "\n")
+
+      code
+    end
+
+    #
+    # Remove whitespace
+    # This can break some codes using inline .NET
+    #
+    # @return [String] code with whitespace stripped
+    def strip_whitespace
+      code.gsub!(WHITESPACE_REGEX, ' ')
+
+      code
+    end
+
+    #
+    # Identify variables and replace them
+    #
+    # @return [String] code with variable names replaced with unique values
+    def sub_vars
+      # Get list of variables, remove reserved
+      get_var_names.each do |var, _sub|
+        code.gsub!(var, "$#{@rig.init_var(var)}")
+      end
+
+      code
+    end
+
+    #
+    # Identify function names and replace them
+    #
+    # @return [String] code with function names replaced with unique
+    #   values
+    def sub_funcs
+      # Find out function names, make map
+      get_func_names.each do |var, _sub|
+        code.gsub!(var, @rig.init_var(var))
+      end
+
+      code
+    end
+
+    #
+    # Perform standard substitutions
+    #
+    # @return [String] code with standard substitution methods applied
+    def standard_subs(subs = %w(strip_comments strip_whitespace sub_funcs sub_vars))
+      # Save us the trouble of breaking injected .NET and such
+      subs.delete('strip_whitespace') unless get_string_literals.empty?
+      # Run selected modifiers
+      subs.each do |modifier|
+        send(modifier)
+      end
+      code.gsub!(EMPTY_LINE_REGEX, '')
+
+      code
+    end
+  end # Obfu
+end
+end
+end