metasploit-framework/lib/rex/exploitation/obfuscatejs.rb

module Rex
module Exploitation

#
# Obfuscates javascript in various ways
#
class ObfuscateJS

	#
	# Obfuscates symbols found within a javascript string.  The symbols
	# argument should have the following format:
	#
	# {
	#    'Variables'  => [ 'var1', ... ],
	#    'Methods'    => [ 'method1', ... ],
	#    'Classes'    => [ { 'Namespace' => 'n', 'Class' => 'y'}, ... ],
	#    'Namespaces' => [ 'n', ... ]
	# }
	#
	# Make sure you order your methods, classes, and namespaces by most
	# specific to least specific to prevent partial substitution.  For
	# instance, if you have two methods (joe and joeBob), you should place
	# joeBob before joe because it is more specific and will be globally
	# replaced before joe is replaced.
	#
	def self.obfuscate(js, opts = {})
		ObfuscateJS.new(js).obfuscate(opts)
	end

	#
	# Initialize an instance of the obfuscator
	#
	def initialize(js)
		@js      = js
		@dynsym  = {}
	end

	#
	# Returns the dynamic symbol associated with the supplied symbol name
	#
	def sym(name)
		@dynsym[name] || name
	end

	#
	# Obfuscates the javascript string passed to the constructor
	#
	def obfuscate(opts = {})
		# Remove our comments
		remove_comments

		# Globally replace symbols
		replace_symbols(opts['Symbols']) if opts['Symbols']

		@js
	end

	#
	# Returns the replaced javascript string
	#
	def to_s
		@js
	end

protected

	# Get rid of comments
	def remove_comments
		@js.gsub!(/(\/\/.+?\n)/m, '')
	end

	# Replace method, class, and namespace symbols found in the javascript
	# string
	def replace_symbols(symbols)
		taken = { }

		# Generate random symbol names
		[ 'Variables', 'Methods', 'Classes', 'Namespaces' ].each { |symtype|
			next if symbols[symtype].nil?
			symbols[symtype].each { |sym|
				dyn = Rex::Text.rand_text_alpha(rand(32)+1) until dyn and not taken.key?(dyn)
	
				taken[dyn] = true
			
				if symtype == 'Classes'
					full_sym = sym['Namespace'] + "." + sym['Class']
					@dynsym[full_sym] = dyn

					@js.gsub!(/#{full_sym}/) { |m|
						sym['Namespace'] + "." + dyn
					}
				else
					@dynsym[sym] = dyn

					@js.gsub!(/#{sym}/, dyn)
				end
			}
		}
	end


end

end
end