Ruby script to get and decrypt a Windows instance's Administrator password.

get_windows_password.rb

#!/usr/bin/env ruby
require 'optparse'
require 'ostruct'
require 'aws-sdk'
require 'base64'
require 'openssl'

class Passworder
  def initialize(args)
    parse_opts(args)
  end

  def parse_opts(args)
    options = OpenStruct.new
    options.private_key = "#{ENV['HOME']}/.ssh/id_rsa"

    opts = OptionParser.new do |o|
      o.banner = "Usage: get_windows_password.rb [options] INSTANCE_ID"
      o.separator ""
      o.separator "options:"

      o.on("-p", "--private-key PRIVATEKEY", "private key used to start instance") do |pk|
        options.private_key = pk
      end

      o.on_tail("-h", "--help", "show this message") do
        puts o
        exit
      end
    end

    opts.parse! args
    @options = options
    @instance_id = args[0]
  end

  def run
    ec2 = AWS::EC2.new
    response = ec2.client.get_password_data(instance_id: @instance_id)

    if response[:password_data].nil?
      $stderr.puts "password not yet available for #{@instance_id}"
      exit 1
    end

    password_data = Base64.decode64 response[:password_data]

    key = OpenSSL::PKey::RSA.new File.read(@options.private_key)
    password = key.private_decrypt password_data

    puts password
  end
end

Passworder.new(ARGV).run

Just used this today and it worked great. Thanks for sharing.