metasploit-framework/msfencode

#!/usr/bin/env ruby

msfbase = File.symlink?(__FILE__) ? File.readlink(__FILE__) : __FILE__
$:.unshift(File.join(File.dirname(msfbase), 'lib'))

require 'rex'
require 'msf/ui'
require 'msf/base'

OutStatus = "[*] "
OutError  = "[-] "

$args = Rex::Parser::Arguments.new(
	"-i" => [ true, "Encode the contents of the supplied file path"                      ],
	"-a" => [ true, "The architecture to encode as"                                      ],
	"-t" => [ true, "The format to display the encoded buffer with (raw, ruby, perl, c)" ],
	"-b" => [ true, "The list of characters to avoid: '\\x00\\xff'"                      ],
	"-s" => [ true, "The maximum size of the encoded data"                               ],
	"-e" => [ true, "The encoder to use"                                                 ],
	"-n" => [ false, "Dump encoder information"                                          ],
	"-h" => [ false, "Help banner"                                                       ],
	"-l" => [ false, "List available encoders"                                           ])

#
# Dump the list of encoders
#
def dump_encoders(arch = nil)
	tbl = Rex::Ui::Text::Table.new(
		'Indent'  => 4,
		'Header'  => "Framework Encoders" + ((arch) ? " (architectures: #{arch})" : ""),
		'Columns' => 
			[
				"Name",
				"Rank",
				"Description"
			])
	cnt = 0

	$framework.encoders.each_module(
		'Arch' => arch ? arch.split(',') : nil) { |name, mod|
		tbl << [ name, mod.rank_to_s, mod.new.name ]

		cnt += 1
	}

	(cnt > 0) ? "\n" + tbl.to_s + "\n" : "\nNo compatible encoders found.\n\n"
end

#
# Returns the list of encoders to try
#
def get_encoders(arch, encoder)
	encoders = []

	if (encoder)
		encoders << $framework.encoders.create(encoder)
	else
		$framework.encoders.each_module_ranked(
			'Arch' => arch ? arch.split(',') : nil) { |name, mod|
			encoders << mod.new
		}
	end

	encoders
end

#
# Nuff said.
#
def usage
	$stderr.puts("\n" + "    Usage: #{$0} <options>\n" + $args.usage)
	exit
end

# Initialize the simplified framework instance.
$framework = Msf::Simple::Framework.create

# Defaults
cmd      = "encode"
arch     = nil
badchars = ''
space    = nil
encoder  = nil
fmt      = "c"
input    = $stdin
options  = ''
delim    = '_|_'

# Parse the argument and rock that shit.
$args.parse(ARGV) { |opt, idx, val|
	case opt
		when "-i"
			begin
				input = File.new(val)
			rescue
				$stderr.puts(OutError + "Failed to open file #{val}: #{$!}")
				exit
			end
		when "-l"
			cmd = "list"
		when "-n"
			cmd = "dump"
		when "-a"
			arch = val
		when "-b"
			badchars = Rex::Text.hex_to_raw(val)
		when "-s"
			space = val.to_i
		when "-t"
			if (val =~ /^(perl|ruby|raw|c)$/)
				fmt = val
			else
				$stderr.puts(OutError + "Invalid format: #{val}")
				exit
			end
		when "-e"
			encoder = val
		when "-h"
			usage
		else
			if (val =~ /=/)
				options += ((options.length > 0) ? delim : "") + "#{val}"
			end
	end	
}

# Get the list of encoders to try
encoders = get_encoders(arch, encoder)

# Process the actual command
case cmd
	when "list"
		$stderr.puts(dump_encoders(arch))
	when "dump"
		enc = encoder ? $framework.encoders.create(encoder) : nil

		if (enc)
			$stderr.puts(Msf::Serializer::ReadableText.dump_module(enc))
		else
			$stderr.puts(OutError + "Invalid encoder specified.")
		end
	when "encode"
		buf = input.read
		
		encoders.each { |enc|
			next if not enc
			begin
				# Imports options
				enc.datastore.import_options_from_s(options, delim)

				# Encode it upt
				raw = enc.encode(buf, badchars)

				# Is it too big?
				if (space and space > 0 and raw.length > space)
					$stderr.puts(OutError + "#{enc.refname} created buffer that is too big (#{raw.length})")
					next
				end

				# Print it out
				$stderr.puts(OutStatus + "#{enc.refname} succeeded, final size #{raw.length}\n\n")
				$stdout.print(Msf::Simple::Buffer.transform(raw, fmt))
				exit

			rescue
				$stderr.puts(OutError + "#{enc.refname} failed: #{$!}")
			end
		}

		$stderr.puts(OutError + "No encoders succeeded.")
end