basic Man-in-the-Middle extension to the Relay-Card

virtualsmartcard/src/vpicc/Makefile.am

@@ -24,6 +24,7 @@ vpicccards_PYTHON = virtualsmartcard/cards/__init__.py \
            virtualsmartcard/cards/ePass.py \
            virtualsmartcard/cards/nPA.py \
            virtualsmartcard/cards/Relay.py \
+           virtualsmartcard/cards/RelayMiddleman.py \
            virtualsmartcard/cards/cryptoflex.py
 
 do_subst = $(SED) \

virtualsmartcard/src/vpicc/vicc.in

@@ -66,6 +66,10 @@ relay.add_argument("--reader",
         type=int,
         default=0,
         help="number of the reader containing the card to be relayed (default: %(default)s)")
+relay.add_argument("--mitm",
+        action="store",
+        type=str,
+        help="relative path to a file containing a Man-in-the-Middle class that is supposed to be used with the relay")
 
 npa = parser.add_argument_group('Emulation of German identity card (`--type=nPA`)')
 npa.add_argument("--ef-cardaccess",
@@ -153,7 +157,7 @@ else:
     hostname = args.hostname
 
 vicc = VirtualICC(args.datasetfile, args.type, hostname, args.port,
-        readernum=args.reader, ef_cardaccess=ef_cardaccess_data,
+        readernum=args.reader, mitmPath=args.mitm, ef_cardaccess=ef_cardaccess_data,
         ef_cardsecurity=ef_cardsecurity_data, ca_key=ca_key_data, cvca=cvca,
         disable_checks=args.disable_ta_checks, esign_ca_cert=esign_ca_cert,
         esign_cert=esign_cert, logginglevel=logginglevel)

virtualsmartcard/src/vpicc/virtualsmartcard/VirtualSmartcard.py

@@ -370,6 +370,30 @@ class Iso7816OS(SmartcardOS):
         self.mf.current = self.mf
 
 
+def loadMitMFromPath(path: str):
+    from importlib import import_module
+    from pathlib import Path
+    def onNth(tup,ind,func):
+        start = tup[0:ind] + (func(tup[ind]),)
+        return start if ind + 1 == 0 else start + tup[ind+1:]
+
+    def pathToModuleName(path):
+        return ".".join(onNth(Path(path).parts,-1,lambda fName : str(Path(fName).stem)))
+
+    mitmModule = import_module(pathToModuleName(path))
+
+    # Sanity Checks
+    if not getattr(mitmModule,"get_MitM",None):
+        raise ValueError("The provided module does not contain a 'get_MitM' method.")
+    mitm = mitmModule.get_MitM()
+    if not getattr(mitm,"handleInPDU",None):
+        raise ValueError("The produced MitM has no 'handleInPDU' method.")
+    if not getattr(mitm,"handleOutPDU",None):
+        raise ValueError("The produced MitM has no 'handleOutPDU' method.")
+
+    return mitm
+
+
 # sizeof(int) taken from asizof-package {{{
 _Csizeof_short = len(struct.pack('h', 0))
 # }}}
@@ -393,7 +417,7 @@ class VirtualICC(object):
     """
 
     def __init__(self, datasetfile, card_type, host, port,
-                 readernum=None, ef_cardsecurity=None, ef_cardaccess=None,
+                 readernum=None, mitmPath=None, ef_cardsecurity=None, ef_cardaccess=None,
                  ca_key=None, cvca=None, disable_checks=False, esign_key=None,
                  esign_ca_cert=None, esign_cert=None,
                  logginglevel=logging.INFO):
@@ -429,7 +453,9 @@ class VirtualICC(object):
             self.os = CryptoflexOS(MF, SAM)
         elif card_type == "relay":
             from virtualsmartcard.cards.Relay import RelayOS
-            self.os = RelayOS(readernum)
+            from virtualsmartcard.cards.RelayMiddleman import RelayMiddleman
+            mitm = loadMitMFromPath(mitmPath) if mitmPath else RelayMiddleman()
+            self.os = RelayOS(readernum,mitm=mitm) 
         elif card_type == "handler_test":
             from virtualsmartcard.cards.HandlerTest import HandlerTestOS
             self.os = HandlerTestOS()

virtualsmartcard/src/vpicc/virtualsmartcard/cards/Relay.py

@@ -22,6 +22,7 @@ import logging
 import smartcard
 import sys
 from virtualsmartcard.VirtualSmartcard import SmartcardOS
+from virtualsmartcard.cards.RelayMiddleman import RelayMiddleman
 
 
 class RelayOS(SmartcardOS):
@@ -31,7 +32,7 @@ class RelayOS(SmartcardOS):
     an actual smart card reader and sends the responses back to the vpcd.
     This class can be used to implement relay or MitM attacks.
     """
-    def __init__(self, readernum):
+    def __init__(self, readernum, mitm=RelayMiddleman()):
         """
         Initialize the connection to the (physical) smart card via a given
         reader
@@ -57,6 +58,8 @@ class RelayOS(SmartcardOS):
 
         logging.info("Connected to card in '%s'", self.reader)
 
+        self.mitm = mitm
+
         atexit.register(self.cleanup)
 
     def cleanup(self):
@@ -116,6 +119,8 @@ class RelayOS(SmartcardOS):
         # sendCommandAPDU() expects a list of APDU bytes
         apdu = map(ord, msg)
 
+        apdu = self.mitm.handleInPDU(apdu)
+
         try:
             rapdu, sw1, sw2 = self.session.sendCommandAPDU(apdu)
         except smartcard.Exceptions.CardConnectionException as e:
@@ -130,5 +135,7 @@ class RelayOS(SmartcardOS):
         else:
             rapdu = rapdu + [sw1, sw2]
 
+        rapdu = self.mitm.handleOutPDU(rapdu)
+
         # return the response APDU as string
         return "".join(map(chr, rapdu))

virtualsmartcard/src/vpicc/virtualsmartcard/cards/RelayMiddleman.py

@@ -0,0 +1,22 @@
+class RelayMiddleman(object):
+    """
+    The RelayMiddleman class serves as a base from which a user might derive
+    their own relay middle man class.  This base class implements the simplest
+    Man-in-the-Middle:  the NoOp.
+    """
+
+    def handleInPDU(self, inPDU: bytes):
+        """
+        This method is called on each PDU that is fed into the realy (vdpu -> vicc).
+        It may be overwritten to modify the packages send from the terminal to the 
+        real smart card.
+        """
+        return inPDU
+
+    def handleOutPDU(self, outPDU: bytes):
+        """
+        This method is called on each PDU that is produced by the relay (vicc -> vdpu).
+        It may be overwritten to modify the packages send from the real smart card to the
+        terminal.
+        """
+        return outPDU