Class: Rex::Parser::GPP

Inherits:
Object
  • Object
show all
Defined in:
lib/rex/parser/group_policy_preferences.rb

Overview

This is a parser for the Windows Group Policy Preferences file format. It’s used by modules/post/windows/gather/credentials/gpp.rb and uses REXML (as opposed to Nokogiri) for its XML parsing. See: msdn.microsoft.com/en-gb/library/cc232587.aspx

Class Method Summary collapse

Class Method Details

.create_tables(results, filetype, domain = nil, dc = nil) ⇒ Object 



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# File 'lib/rex/parser/group_policy_preferences.rb', line 88

def self.create_tables(results, filetype, domain=nil, dc=nil)
  tables = []
  results.each do |result|
    table = Rex::Ui::Text::Table.new(
      'Header'     => 'Group Policy Credential Info',
      'Indent'     => 1,
      'SortIndex'  => -1,
      'Columns'    =>
      [
        'Name',
        'Value',
      ]
    )

    table << ["TYPE", filetype]
    table << ["USERNAME", result[:USER]]
    table << ["PASSWORD", result[:PASS]]
    table << ["DOMAIN CONTROLLER", dc] unless dc.nil? || dc.empty?
    table << ["DOMAIN", domain] unless domain.nil? || domain.empty?
    table << ["CHANGED", result[:CHANGED]]
    table << ["EXPIRES", result[:EXPIRES]] unless result[:EXPIRES].nil? || result[:EXPIRES].empty?
    table << ["NEVER_EXPIRES?", result[:NEVER_EXPIRES]] unless result[:NEVER_EXPIRES].nil?
    table << ["DISABLED", result[:DISABLED]] unless result[:DISABLED].nil?
    table << ["PATH", result[:PATH]] unless result[:PATH].nil? || result[:PATH].empty?
    table << ["DATASOURCE", result[:DSN]] unless result[:DSN].nil? || result[:DSN].empty?
    table << ["DRIVER", result[:DRIVER]] unless result[:DRIVER].nil? || result[:DRIVER].empty?
    table << ["TASK", result[:TASK]] unless result[:TASK].nil? || result[:TASK].empty?
    table << ["SERVICE", result[:SERVICE]] unless result[:SERVICE].nil? || result[:SERVICE].empty?

    unless result[:ATTRIBUTES].nil? || result[:ATTRIBUTES].empty?
      result[:ATTRIBUTES].each do |dsn_attribute|
        table << ["ATTRIBUTE", "#{dsn_attribute[:A_NAME]} - #{dsn_attribute[:A_VALUE]}"]
      end
    end

    tables << table
  end

  tables
end

.decrypt(encrypted_data) ⇒ Object

Decrypts passwords using Microsoft’s published key: msdn.microsoft.com/en-us/library/cc422924.aspx



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# File 'lib/rex/parser/group_policy_preferences.rb', line 131

def self.decrypt(encrypted_data)
  password = ""
  return password unless encrypted_data

  password = ""
  retries = 0
  original_data = encrypted_data.dup

  begin
    mod = encrypted_data.length % 4

    # PowerSploit code strips the last character, unsure why...
    case mod
    when 1
      encrypted_data = encrypted_data[0..-2]
    when 2, 3
      padding = '=' * (4 - mod)
      encrypted_data = "#{encrypted_data}#{padding}"
    end

    # Strict base64 decoding used here
    decoded = encrypted_data.unpack('m0').first
  rescue ::ArgumentError => e
    # Appears to be some junk UTF-8 Padding appended at times in
    # Win2k8 (not in Win2k8R2)
    # Lets try stripping junk and see if we can decrypt
    if retries < 8
      retries += 1
      original_data = original_data[0..-2]
      encrypted_data = original_data
      retry
    else
      return password
    end
  end

  key = "\x4e\x99\x06\xe8\xfc\xb6\x6c\xc9\xfa\xf4\x93\x10\x62\x0f\xfe\xe8\xf4\x96\xe8\x06\xcc\x05\x79\x90\x20\x9b\x09\xa4\x33\xb6\x6c\x1b"
  aes = OpenSSL::Cipher::Cipher.new("AES-256-CBC")
  begin
    aes.decrypt
    aes.key = key
    plaintext = aes.update(decoded)
    plaintext << aes.final
    password = plaintext.unpack('v*').pack('C*') # UNICODE conversion
  rescue OpenSSL::Cipher::CipherError => e
    puts "Unable to decode: \"#{encrypted_data}\" Exception: #{e}"
  end

  password
end

.parse(data) ⇒ Object 



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# File 'lib/rex/parser/group_policy_preferences.rb', line 15

def self.parse(data)
  if data.nil?
    return []
  end

  xml = REXML::Document.new(data).root
  results = []

  unless xml and xml.elements and xml.elements.to_a("//Properties")
    return []
  end

  xml.elements.to_a("//Properties").each do |node|
    epassword = node.attributes['cpassword']
    next if epassword.to_s.empty?
    password = self.decrypt(epassword)

    user = node.attributes['runAs'] if node.attributes['runAs']
    user = node.attributes['accountName'] if node.attributes['accountName']
    user = node.attributes['username'] if node.attributes['username']
    user = node.attributes['userName'] if node.attributes['userName']
    user = node.attributes['newName'] unless node.attributes['newName'].nil? || node.attributes['newName'].empty?
    changed = node.parent.attributes['changed']

    # Printers and Shares
    path = node.attributes['path']

    # Datasources
    dsn = node.attributes['dsn']
    driver = node.attributes['driver']

    # Tasks
    app_name = node.attributes['appName']

    # Services
    service = node.attributes['serviceName']

    # Groups
    expires = node.attributes['expires']
    never_expires = node.attributes['neverExpires']
    disabled = node.attributes['acctDisabled']

    result = {
      :USER => user,
      :PASS => password,
      :CHANGED => changed
    }

    result.merge!({ :EXPIRES => expires }) unless expires.nil? || expires.empty?
    result.merge!({ :NEVER_EXPIRES => never_expires.to_i }) unless never_expires.nil? || never_expires.empty?
    result.merge!({ :DISABLED => disabled.to_i }) unless disabled.nil? || disabled.empty?
    result.merge!({ :PATH => path }) unless path.nil? || path.empty?
    result.merge!({ :DATASOURCE => dsn }) unless dsn.nil? || dsn.empty?
    result.merge!({ :DRIVER => driver }) unless driver.nil? || driver.empty?
    result.merge!({ :TASK => app_name }) unless app_name.nil? || app_name.empty?
    result.merge!({ :SERVICE => service }) unless service.nil? || service.empty?

    attributes = []
    node.elements.each('//Attributes//Attribute') do |dsn_attribute|
      attributes << {
        :A_NAME => dsn_attribute.attributes['name'],
        :A_VALUE => dsn_attribute.attributes['value']
      }
    end

    result.merge!({ :ATTRIBUTES => attributes }) unless attributes.empty?

    results << result
  end

  results
end