Land #13778, [GSOC 2020] - EV1 - Conditionality system for module options

lib/msf/base/serializer/readable_text.rb

@@ -1,4 +1,7 @@
 # -*- coding: binary -*-
+
+require 'msf/core/opt_condition'
+
 module Msf
 module Serializer
 
@@ -555,6 +558,7 @@ class ReadableText
     mod.options.sorted.each do |name, opt|
       val = mod.datastore[name].nil? ? opt.default : mod.datastore[name]
 
+      next unless Msf::OptCondition.show_option(mod, opt)
       next if (opt.advanced?)
       next if (opt.evasion?)
       next if (missing && opt.valid?(val))
@@ -599,6 +603,7 @@ class ReadableText
 
     mod.options.sorted.each do |name, opt|
       next unless opt.advanced?
+      next unless Msf::OptCondition.show_option(mod, opt)
       val = mod.datastore[name].nil? ? opt.default : mod.datastore[name]
       tbl << [ name, opt.display_value(val), opt.required? ? "yes" : "no", opt.desc ]
     end

lib/msf/core/exploit/cmdstager.rb

@@ -55,6 +55,13 @@ module Exploit::CmdStager
     flavors = STAGERS.keys if flavors.empty?
     flavors.unshift('auto')
 
+    server_conditions = ['CMDSTAGER::FLAVOR', 'in', %w{certutil tftp wget curl fetch lwprequest psh_invokewebrequest}]
+    register_options(
+      [
+        OptAddressLocal.new('SRVHOST', [true, 'The local host or network interface to listen on. This must be an address on the local machine or 0.0.0.0 to listen on all addresses.', '0.0.0.0' ], conditions: server_conditions),
+        OptPort.new('SRVPORT', [true, "The local port to listen on.", 8080], conditions: server_conditions)
+      ])
+
     register_advanced_options(
       [
         OptEnum.new('CMDSTAGER::FLAVOR', [false, 'The CMD Stager to use.', 'auto', flavors]),

lib/msf/core/opt_base.rb

@@ -26,12 +26,13 @@ module Msf
     # also be a string as standin for the required description field.
     #
     def initialize(in_name, attrs = [],
-                   required: false, desc: nil, default: nil, enums: [], regex: nil, aliases: [], max_length: nil)
+                   required: false, desc: nil, default: nil, conditions: [], enums: [], regex: nil, aliases: [], max_length: nil)
       self.name     = in_name
       self.advanced = false
       self.evasion  = false
       self.aliases  = aliases
       self.max_length = max_length
+      self.conditions = conditions
 
       if attrs.is_a?(String) || attrs.length == 0
         self.required = required
@@ -59,7 +60,7 @@ module Msf
       unless max_length.nil?
         self.desc += " Max parameter length: #{max_length} characters"
       end
-      
+
       if regex_temp
         # convert to string
         regex_temp = regex_temp.to_s if regex_temp.is_a? Regexp
@@ -190,6 +191,10 @@ module Msf
     #
     attr_accessor :owner
     #
+    # The list of potential conditions
+    #
+    attr_accessor :conditions
+    #
     # The list of potential valid values
     #
     attr_accessor :enums
@@ -201,11 +206,11 @@ module Msf
     # Aliases for this option for backward compatibility
     #
     attr_accessor :aliases
-    # 
+    #
     # The max length of the input value
     #
     attr_accessor :max_length
-    
+
     protected
 
     attr_writer   :required, :desc, :default # :nodoc:

lib/msf/core/opt_bool.rb

@@ -8,7 +8,7 @@ module Msf
 
     # This overrides default from 'nil' to 'false'
     def initialize(in_name, attrs = [],
-                   required: true, desc: nil, default: false, aliases: [])
+                   default: false, **kwargs)
       super
     end
 

lib/msf/core/opt_condition.rb

@@ -0,0 +1,39 @@
+# -*- coding: binary -*-
+module Msf
+  module OptCondition
+
+    # Check a condition's result
+    def self.eval_condition(left_value, operator, right_value)
+      case operator.to_sym
+      when :==
+        right_value == left_value
+      when :!=
+        right_value != left_value
+      when :in
+        right_value.include?(left_value)
+      when :nin
+        !right_value.include?(left_value)
+      end
+    end
+
+    # Check an OPTION conditions. This function supports
+    # dump_options()
+    def self.show_option(mod, opt)
+      return true if opt.conditions.empty?
+
+      left_source = opt.conditions[0]
+      operator = opt.conditions[1]
+      right_value = opt.conditions[2]
+      if left_source == 'ACTION'
+        left_value = mod.action.name.to_s
+      elsif left_source == 'TARGET'
+        left_value = mod.target.name.to_s
+      else
+        left_value = mod.datastore[left_source] || opt.default
+      end
+
+      eval_condition(left_value, operator, right_value)
+    end
+
+  end
+end

lib/msf/core/opt_enum.rb

@@ -13,7 +13,7 @@ module Msf
 
     # This overrides required default from 'false' to 'true'
     def initialize(in_name, attrs = [],
-                   required: true, desc: nil, default: nil, enums: [], aliases: [])
+                   required: true, **kwargs)
       super
     end