smbserver.py: add signing (NTLM/Kerberos) support, add read-only option

examples/describeTicket.py

@@ -38,7 +38,7 @@
 from impacket.krb5.asn1 import TGS_REP, EncTicketPart, AD_IF_RELEVANT
 from impacket.krb5.ccache import CCache
 from impacket.krb5.constants import ChecksumTypes
-from impacket.krb5.crypto import Key, _enctype_table, InvalidChecksum, string_to_key
+from impacket.krb5.crypto import Key, _enctype_table, InvalidChecksum, string_to_key, generate_kerberos_keys
 from impacket.ldap.ldaptypes import LDAP_SID
 
 PSID = PRPC_SID
@@ -290,7 +290,7 @@ def parse_ccache(args):
             logging.debug("No kvno in ticket, skipping")
             logging.info("  %-28s: %d" % ("Key version number (kvno)", decodedTicket['ticket']['enc-part']['kvno']))
         logging.debug("Handling Kerberos keys")
-        ekeys = generate_kerberos_keys(args)
+        ekeys = generate_kerberos_keys(args.rc4, args.aes, args.password, args.hex_pass, args.salt, args.user, args.domain)
 
         # copypasta from krbrelayx.py
         # Select the correct encryption key
@@ -630,56 +630,6 @@ def PACparseGroupIds(data):
     return parsed_tuPAC
 
 
-def generate_kerberos_keys(args):
-    # copypasta from krbrelayx.py
-    # Store Kerberos keys
-    keys = {}
-    if args.rc4:
-        keys[int(constants.EncryptionTypes.rc4_hmac.value)] = unhexlify(args.rc4)
-    if args.aes:
-        if len(args.aes) == 64:
-            keys[int(constants.EncryptionTypes.aes256_cts_hmac_sha1_96.value)] = unhexlify(args.aes)
-        else:
-            keys[int(constants.EncryptionTypes.aes128_cts_hmac_sha1_96.value)] = unhexlify(args.aes)
-    ekeys = {}
-    for kt, key in keys.items():
-        ekeys[kt] = Key(kt, key)
-
-    allciphers = [
-        int(constants.EncryptionTypes.rc4_hmac.value),
-        int(constants.EncryptionTypes.aes256_cts_hmac_sha1_96.value),
-        int(constants.EncryptionTypes.aes128_cts_hmac_sha1_96.value)
-    ]
-
-    # Calculate Kerberos keys from specified password/salt
-    if args.password or args.hex_pass:
-        if not args.salt and args.user and args.domain: # https://www.thehacker.recipes/ad/movement/kerberos
-            if args.user.endswith('$'):
-                args.salt = "%shost%s.%s" % (args.domain.upper(), args.user.rstrip('$').lower(), args.domain.lower())
-            else:
-                args.salt = "%s%s" % (args.domain.upper(), args.user)
-        for cipher in allciphers:
-            if cipher == 23 and args.hex_pass:
-                # RC4 calculation is done manually for raw passwords
-                md4 = MD4.new()
-                md4.update(unhexlify(args.hex_pass))
-                ekeys[cipher] = Key(cipher, md4.digest())
-                logging.debug('Calculated type %s (%d) Kerberos key: %s' % (constants.EncryptionTypes(cipher).name, cipher, hexlify(ekeys[cipher].contents).decode('utf-8')))
-            elif args.salt:
-                # Do conversion magic for raw passwords
-                if args.hex_pass:
-                    rawsecret = unhexlify(args.hex_pass).decode('utf-16-le', 'replace').encode('utf-8', 'replace')
-                else:
-                    # If not raw, it was specified from the command line, assume it's not UTF-16
-                    rawsecret = args.password
-                ekeys[cipher] = string_to_key(cipher, rawsecret, args.salt)
-                logging.debug('Calculated type %s (%d) Kerberos key: %s' % (constants.EncryptionTypes(cipher).name, cipher, hexlify(ekeys[cipher].contents).decode('utf-8')))
-            else:
-                logging.debug('Cannot calculate type %s (%d) Kerberos key: salt is None: Missing -s/--salt or (-u/--user and -d/--domain)' % (constants.EncryptionTypes(cipher).name, cipher))
-    else:
-        logging.debug('No password (-p/--password or -hp/--hex_pass supplied, skipping Kerberos keys calculation')
-    return ekeys
-
 
 def kerberoast_from_ccache(decodedTGS, spn, username, domain):
     try:

examples/smbserver.py

@@ -39,9 +39,18 @@
     parser.add_argument('-comment', action='store', help='share\'s comment to display when asked for shares')
     parser.add_argument('-username', action="store", help='Username to authenticate clients')
     parser.add_argument('-password', action="store", help='Password for the Username')
+    parser.add_argument('-computeraccountname', action="store", help='computer account name to authenticate arbitrary clients with signing via NetLogon')
+    parser.add_argument('-computeraccounthash', action="store", help='computer account NT hash to authenticate arbitrary clients with signing via NetLogon')
+    parser.add_argument('-computeraccountaes', action="store", help='computer account AES key to authenticate arbitrary clients with signing via Kerberos')
+    parser.add_argument('-computeraccountpassword', action="store", help='computer account NT hash to authenticate arbitrary clients with signing via Kerberos')
+    parser.add_argument('-computeraccountdomain', action="store", help='DC IP/hostname to authenticate arbitrary clients with signing via NetLogon')
+    parser.add_argument('-dcip', action="store", help='IP of domain controller to authenticate arbitrary clients with signing via NetLogon')
     parser.add_argument('-hashes', action="store", metavar = "LMHASH:NTHASH", help='NTLM hashes for the Username, format is LMHASH:NTHASH')
     parser.add_argument('-ts', action='store_true', help='Adds timestamp to every logging output')
     parser.add_argument('-debug', action='store_true', help='Turn DEBUG output ON')
+    parser.add_argument('-readonly', action='store_true', help='Only allow reading of files')
+    parser.add_argument('-disablekerberos', action='store_true', help='Do not offer Kerberos authentication')
+    parser.add_argument('-disablentlm', action='store_true', help='Do not offer NTLM authentication')
     parser.add_argument('-ip', '--interface-address', action='store', default='0.0.0.0', help='ip address of listening interface')
     parser.add_argument('-port', action='store', default='445', help='TCP port for listening incoming connections (default 445)')
     parser.add_argument('-smb2support', action='store_true', default=False, help='SMB2 Support (experimental!)')
@@ -70,8 +79,10 @@
         logging.info('Switching output to file %s' % options.outputfile)
         server.setLogFile(options.outputfile)
 
-    server.addShare(options.shareName.upper(), options.sharePath, comment)
+    server.addShare(options.shareName.upper(), options.sharePath, comment, readOnly="yes" if options.readonly else "no")
     server.setSMB2Support(options.smb2support)
+    server.setKerberosSupport(not options.disablekerberos)
+    server.setNTLMSupport(not options.disablentlm)
 
     # If a user was specified, let's add it to the credentials for the SMBServer. If no user is specified, anonymous
     # connections will be allowed
@@ -91,6 +102,20 @@
 
         server.addCredential(options.username, 0, lmhash, nthash)
 
+    # If we want clients to be able to connect to us which enforce signing, we need a computer account to properly setup the connection
+    # Only works with SMB2
+    # FIXME: For NTLM just NT hash is supported for now
+    required_secure_server_options = [options.computeraccountname, options.computeraccountdomain, options.dcip]
+    at_least_one_secure_server_options = [options.computeraccounthash, options.computeraccountaes, options.computeraccountpassword]
+    if any(required_secure_server_options):
+        if not all(required_secure_server_options):
+            logging.critical("All of the following options need to be set for accepting signed connections from arbitrary users in the domain: -computeraccountname, -computeraccountdomain, -dcip")
+            sys.exit(1)
+        if not any(at_least_one_secure_server_options):
+            logging.critical("At least one of the following options need to be set for accepting signed connections from arbitrary users in the domain: -computeraccounthash, -computeraccountaes, -computeraccountpassword")
+            sys.exit(1)
+        server.setComputerAccount(options.computeraccountname, options.computeraccounthash, options.computeraccountaes, options.computeraccountpassword, options.computeraccountdomain, options.dcip)
+
     # Here you can set a custom SMB challenge in hex format
     # If empty defaults to '4141414141414141'
     # (remember: must be 16 hex bytes long)

impacket/krb5/asn1.py

@@ -334,6 +334,15 @@ class AP_REQ(univ.Sequence):
         _sequence_component('authenticator', 4, EncryptedData())
         )
 
+class GSSAPIHeader_KRB5_AP_REQ(univ.Sequence):
+    tagSet = univ.Sequence.tagSet.tagImplicitly(tag.Tag(tag.tagClassApplication, tag.tagFormatConstructed, 0))
+    componentType = namedtype.NamedTypes(
+        namedtype.NamedType('tokenOid', univ.ObjectIdentifier()),
+        # Actualy this is a constant 0x0001, but this decodes as an asn1 boolean
+        namedtype.NamedType('krb5_ap_req', univ.Boolean()),
+        namedtype.NamedType('apReq', AP_REQ()),
+    )
+
 class AP_REP(univ.Sequence):
     tagSet = _application_tag(constants.ApplicationTagNumbers.AP_REP.value)
     componentType = namedtype.NamedTypes(

impacket/krb5/crypto.py

@@ -38,7 +38,7 @@
 # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 # OF THE POSSIBILITY OF SUCH DAMAGE.
 #
-from binascii import unhexlify
+from binascii import hexlify, unhexlify
 from functools import reduce
 from os import urandom
 # XXX current status:
@@ -61,7 +61,8 @@
 from Cryptodome.Protocol.KDF import PBKDF2
 from Cryptodome.Util.number import GCD as gcd
 from six import b, PY3, indexbytes, binary_type
-
+from impacket.krb5 import constants
+import logging
 
 def get_random_bytes(lenBytes):
     # We don't really need super strong randomness here to use PyCrypto.Random
@@ -718,3 +719,53 @@ def prfplus(key, pepper, l):
     e = _get_enctype_profile(enctype)
     return e.random_to_key(_xorbytes(bytearray(prfplus(key1, pepper1, e.seedsize)),
                                      bytearray(prfplus(key2, pepper2, e.seedsize))))
+
+def generate_kerberos_keys(rc4=None, aes=None, password=None, hex_pass=None, salt=None, user=None, domain=None):
+    # copypasta from krbrelayx.py
+    # Store Kerberos keys
+    keys = {}
+    if rc4:
+        keys[int(constants.EncryptionTypes.rc4_hmac.value)] = unhexlify(rc4)
+    if aes:
+        if len(aes) == 64:
+            keys[int(constants.EncryptionTypes.aes256_cts_hmac_sha1_96.value)] = unhexlify(aes)
+        else:
+            keys[int(constants.EncryptionTypes.aes128_cts_hmac_sha1_96.value)] = unhexlify(aes)
+    ekeys = {}
+    for kt, key in keys.items():
+        ekeys[kt] = Key(kt, key)
+
+    allciphers = [
+        int(constants.EncryptionTypes.rc4_hmac.value),
+        int(constants.EncryptionTypes.aes256_cts_hmac_sha1_96.value),
+        int(constants.EncryptionTypes.aes128_cts_hmac_sha1_96.value)
+    ]
+
+    # Calculate Kerberos keys from specified password/salt
+    if password or hex_pass:
+        if not salt and user and domain: # https://www.thehacker.recipes/ad/movement/kerberos
+            if user.endswith('$'):
+                salt = "%shost%s.%s" % (domain.upper(), user.rstrip('$').lower(), domain.lower())
+            else:
+                salt = "%s%s" % (domain.upper(), user)
+        for cipher in allciphers:
+            if cipher == 23 and hex_pass:
+                # RC4 calculation is done manually for raw passwords
+                md4 = MD4.new()
+                md4.update(unhexlify(hex_pass))
+                ekeys[cipher] = Key(cipher, md4.digest())
+                logging.debug('Calculated type %s (%d) Kerberos key: %s' % (constants.EncryptionTypes(cipher).name, cipher, hexlify(ekeys[cipher].contents).decode('utf-8')))
+            elif salt:
+                # Do conversion magic for raw passwords
+                if hex_pass:
+                    rawsecret = unhexlify(hex_pass).decode('utf-16-le', 'replace').encode('utf-8', 'replace')
+                else:
+                    # If not raw, it was specified from the command line, assume it's not UTF-16
+                    rawsecret = password
+                ekeys[cipher] = string_to_key(cipher, rawsecret, salt)
+                logging.debug('Calculated type %s (%d) Kerberos key: %s' % (constants.EncryptionTypes(cipher).name, cipher, hexlify(ekeys[cipher].contents).decode('utf-8')))
+            else:
+                logging.debug('Cannot calculate type %s (%d) Kerberos key: salt is None: Missing -s/--salt or (-u/--user and -d/--domain)' % (constants.EncryptionTypes(cipher).name, cipher))
+    else:
+        logging.debug('No password (-p/--password or -hp/--hex_pass supplied, skipping Kerberos keys calculation')
+    return ekeys

impacket/smb3structs.py

@@ -538,6 +538,9 @@ class SMB3Packet(SMBPacketBase):
         ('Data',':=""'),
     )
 
+
+class Empty(Structure):
+    pass
 class SMB2Error(Structure):
     structure = (
         ('StructureSize','<H=9'),