Class: JSObfu::Scope

Inherits:

Hash

• Object
• Hash
• JSObfu::Scope

show all

Defined in:

lib/jsobfu/scope.rb

Overview

Constant Summary

RESERVED_KEYWORDS =

these keywords should never be used as a random var name source: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Reserved_Words

%w(
break case catch continue debugger default delete do else finally
for function if in instanceof new return switch this throw try
typeof var void while with class enum export extends import super
implements interface let package private protected public static yield
const let

BUILTIN_VARS =

these vars should not be shadowed as they in the exploit code, and generating them would cause problems.

%w(
String window unescape location chrome document navigator location
frames ActiveXObject XMLHttpRequest Function eval Object Math CSS
parent opener event frameElement Error TypeError setTimeout setInterval
top arguments Array Date

Instance Attribute Summary (collapse)

• - (JSObfu::Scope) parent

  Parent that spawned this scope.

• - (Hash) renames

  Mapping old var names to random ones.

Instance Method Summary (collapse)

• - (Boolean) empty?

  Scope has members.

• - (Boolean) has_key?(key)

  Check if we've used this var before.

• - (Scope) initialize(opts = {}) constructor

  A new instance of Scope.

• - (Object) pop!

  "Consumes" the parent and replaces self with it.

• - (Object) push!

  replaces this Scope in the "parent" chain with a copy, empties current scope, and returns.

• - (String) random_string(len)

  A random string that can be used as a var.

• - (String) random_var_name

  Generates a unique, "safe" random variable.

• - (String) rename_var(var_name, opts = {})

  Re-maps your var_name to a unique, random names in the current scope.

• - (Object) top
• - (Boolean) top?

  Scope has no parent.

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# File 'lib/jsobfu/scope.rb', line 38

def initialize(opts={})
  @parent         = opts[:parent]
  @first_char_set = opts[:first_char_set] || [*'A'..'Z']+[*'a'..'z']+['_', '$']
  @char_set       = opts[:first_char_set] || @first_char_set + [*'0'..'9']
  @min_len        = opts[:min_len] || 1
  @renames        = {}
end

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# File 'lib/jsobfu/scope.rb', line 29

def parent
  @parent
end

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# File 'lib/jsobfu/scope.rb', line 32

def renames
  @renames
end

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# File 'lib/jsobfu/scope.rb', line 98

def empty?
  self.keys.empty? and (parent.nil? or parent.empty?)
end

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# File 'lib/jsobfu/scope.rb', line 117

def has_key?(key)
  super or (parent and parent.has_key?(key))
end

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# File 'lib/jsobfu/scope.rb', line 134

def pop!
  clear
  if @parent
    merge! @parent
    @renames = @parent.renames
    @parent = @parent.parent
  end
end

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# File 'lib/jsobfu/scope.rb', line 124

def push!
  replacement = dup
  replacement.parent = @parent
  replacement.renames = @renames
  @renames = {}
  @parent = replacement
  clear
end

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# File 'lib/jsobfu/scope.rb', line 144

def random_string(len)
  @first_char_set.sample + (len-1).times.map { @char_set.sample }.join
end

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# File 'lib/jsobfu/scope.rb', line 48

def random_var_name
  len = @min_len
  loop do
    text = random_string(len)
    unless has_key?(text) or
      RESERVED_KEYWORDS.include?(text) or
      BUILTIN_VARS.include?(text)

      self[text] = nil

      return text
    end
    len += 1
  end
end

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# File 'lib/jsobfu/scope.rb', line 76

def rename_var(var_name, opts={})
  return var_name if BUILTIN_VARS.include?(var_name)

  generate = opts.fetch(:generate, true)
  unresolved = opts.fetch(:unresolved, [])
  renamed = @renames[var_name]

  if renamed.nil? and parent
    renamed = parent.rename_var(var_name, :generate => false)
  end

  if renamed.nil? and generate
    @renames[var_name] = random_var_name
    renamed = @renames[var_name]
  end

  #puts "Mapped #{var_name} => #{renamed}" if renamed

  renamed
end

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# File 'lib/jsobfu/scope.rb', line 107

def top
  p = self
  p = p.parent until p.parent.nil?
  p
end

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# File 'lib/jsobfu/scope.rb', line 103

def top?
  parent.nil?
end