85 lines
1.8 KiB
Ruby
85 lines
1.8 KiB
Ruby
##
|
|
# $Id: $
|
|
##
|
|
|
|
##
|
|
#
|
|
# RFB protocol support
|
|
#
|
|
# by Joshua J. Drake <jduck>
|
|
#
|
|
# Based on:
|
|
# vnc_auth_none contributed by Matteo Cantoni <goony[at]nothink.org>
|
|
# vnc_auth_login contributed by carstein <carstein.sec[at]gmail.com>
|
|
#
|
|
##
|
|
|
|
# Required for VNC authentication
|
|
require 'openssl'
|
|
|
|
module Rex
|
|
module Proto
|
|
module RFB
|
|
|
|
##
|
|
# A bit of information about the DES algorithm was found here:
|
|
# http://www.vidarholen.net/contents/junk/vnc.html
|
|
#
|
|
# In addition, VNC uses two individual 8 byte block encryptions rather than
|
|
# using any block mode (like cbc, ecb, etc).
|
|
##
|
|
|
|
class Cipher
|
|
|
|
def self.mangle_password(password)
|
|
key = ''
|
|
key = password.dup if password
|
|
key.slice!(8,key.length) if key.length > 8
|
|
key << "\x00" * (8 - key.length) if key.length < 8
|
|
|
|
# We have to mangle the key so the LSB are kept vs the MSB
|
|
[key.unpack('B*').first.scan(/.{8}/).map! { |e| e.reverse }.join].pack('B*')
|
|
end
|
|
|
|
def self.encrypt(plain, password)
|
|
key = self.mangle_password(password)
|
|
|
|
# pad the plain to 16 chars
|
|
plain << ("\x00" * (16 - plain.length)) if plain.length < 16
|
|
|
|
# VNC auth does two 8-byte blocks individually instead supporting some block mode
|
|
cipher = ''
|
|
2.times { |x|
|
|
c = OpenSSL::Cipher::Cipher.new('des')
|
|
c.encrypt
|
|
c.key = key
|
|
cipher << c.update(plain[x*8, 8])
|
|
}
|
|
|
|
cipher
|
|
end
|
|
|
|
#
|
|
# NOTE: The default password is that of winvnc/etc which is used for
|
|
# encrypting the password(s) on disk/in registry.
|
|
#
|
|
def self.decrypt(cipher, password = "\x17\x52\x6b\x06\x23\x4e\x58\x07")
|
|
key = self.mangle_password(password)
|
|
|
|
# pad the cipher text to 9 bytes
|
|
cipher << ("\x00" * (9 - cipher.length)) if cipher.length < 9
|
|
|
|
# NOTE: This only does one 8 byte block
|
|
plain = ''
|
|
c = OpenSSL::Cipher::Cipher.new('des')
|
|
c.decrypt
|
|
c.key = key
|
|
c.update(cipher)
|
|
end
|
|
|
|
end
|
|
|
|
end
|
|
end
|
|
end
|