cisco_decrypt.py

cisco_decrypt.py

#!/usr/bin/env python
# coding=utf-8
"""
    My version of cisco_decrypt.py

    Version 1.0 - Nick Bettison - linickx.com

    USAGE:
    ------

    linickx:~ $ cisco_decrypt.py -e "023530612D5319347A"
    STZF5vuV
    linickx:~ $

    or simply...

    linickx:~ $ cisco_decrypt.py 023530612D5319347A
    STZF5vuV
    linickx:~ $

    or even...

    linickx:~ $ cisco_decrypt.py 023530612D5319347A 095C4F1A0A1218000F
    STZF5vuV
    password
    linickx:~ $
"""
import sys
import re
import logging

logging.basicConfig(format='[%(levelname)s] %(asctime)s %(message)s', level=logging.WARNING)
logger = logging.getLogger("cisco_decrypt")

from optparse import OptionParser

class CiscoPassword:
    """
        Original Work by David M Pennington
        http://www.pennington.net/py/cisco_decrypt/
        Converted from perl code that was written by jbash at cisco.com.

        COPYRIGHT, LICENSE, and WARRANTY
        ================================
        GNU General Public License, v3

        This software is (c) 2007 by David Michael Pennington.  It can be
        reused under the terms of the GPL v3 license provided that proper
        credit for the work of the author is preserved in the form  of this
        copyright notice and license for this package.

        No warranty of any kind is expressed or implied.  By using this software, you
        are agreeing to assume ALL risks and David M Pennington shall NOT be liable
        for ANY damages resulting from its use.

        If you chose to bring legal action against the author, you are automatically
        granting him the remainder of your lifetime salary, ownership of your
        retirement plan (you do have one, right??), the deed to your house assuming
        it isn't a pile of junk, and your perpetual indentured servitude under his
        direction.
    """

    def __init__(self, string):
        self.string = string
        self.decrypted = True

    def passed(self):
        """
            Did is pass or fail
        """
        return self.decrypted

    def decrypt(self):
        """Cisco Type 7 password decryption.
        """
        ep = self.string

        xlat = (0x64, 0x73, 0x66, 0x64, 0x3b, 0x6b, 0x66, 0x6f, 0x41, 0x2c,
                 0x2e, 0x69, 0x79, 0x65, 0x77, 0x72, 0x6b, 0x6c, 0x64, 0x4a,
                 0x4b, 0x44, 0x48, 0x53, 0x55, 0x42)
        dp = ""
        regex = re.compile("^(..)(.+)")

        if len(ep) & 1:
            logger.error("Invalid Hash - %s - Odd number length string", ep)
            self.decrypted = False
        else:
            result = regex.search(ep)
            try:
                s, e = int(result.group(1)), result.group(2)
            except ValueError:
                # typically get a ValueError for int( result.group(1))) because
                # the method was called with an unencrypted password.  For now
                # SILENTLY bypass the error
                s, e = (0, "")
                logger.error("Invalid Hash - %s - Did you paste a clear txt string?", ep)
                self.decrypted = False
            for ii in range(0, len(e), 2):
                # int( blah, 16) assumes blah is base16... cool
                magic = int(re.search(".{%s}(..)" % ii, e).group(1), 16)
                #print("S = %s" % s)
                if s <= 25:
                    # Algorithm appears unpublished after s = 25
                    newchar = "%c" % (magic ^ int(xlat[int(s)]))
                else:
                    newchar = "?"
                dp = dp + str(newchar)
                s = s + 1
            if s > 25:
                logger.warning("Password Decryption Failed - Patial response returned")
                self.decrypted = False

        return dp


# Output Array of all things!
logger.debug(str(sys.argv))

# Loop thru inputs
for thing in sys.argv:

    # ignore filenames
    regmatch = re.match(r'.*\.py$', thing)
    if regmatch:
        logger.debug("Ingoring... %s", thing)
        continue

    # ignore anyone using minus swithes, such as -e in the original documentation
    regmatch = re.match('^-', thing)
    if regmatch:
        logger.debug("Ingoring... %s", thing)
        continue

    # Ok, this is what we're working with
    logger.debug("Input is %s", thing)

    # Crack it!
    crack = CiscoPassword(thing)
    print(crack.decrypt())

    # Exit with error if the crack didn't completly pass
    if not crack.passed():
        sys.exit(1)

"""
COPYRIGHT, LICENSE, and WARRANTY
================================
GNU General Public License, v3

This software is (c) 2017 by Nick Bettison.  It can be
reused under the terms of the GPL v3 license provided that proper
credit for the work of the author is preserved in the form  of this
copyright notice and license for this package.

No warranty of any kind is expressed or implied.  By using this software, you
are agreeing to assume ALL risks and Nick Bettison shall NOT be liable
for ANY damages resulting from its use.

If you chose to bring legal action against the author, you are automatically
granting him the remainder of your lifetime salary, ownership of your
retirement plan (you do have one, right??), the deed to your house assuming
it isn't a pile of junk, and your perpetual indentured servitude under his
direction.
"""