Add support for salted mac generation, fix issue 17

2015-02-10 11:39:26 +01:00
parent 9e50c2292d
commit a01eb57cef
2 changed files with 77 additions and 17 deletions
--- a/rdpy/protocol/rdp/pdu/layer.py
+++ b/rdpy/protocol/rdp/pdu/layer.py
@@ -180,6 +180,9 @@ class Client(PDULayer):
        for cap in pdu.pduMessage.capabilitySets._array:
            self._serverCapabilities[cap.capabilitySetType] = cap
            
+        #secure checksum cap here maybe protocol (another) design error
+        self._transport._enableSecureCheckSum = bool(self._serverCapabilities[caps.CapsType.CAPSTYPE_GENERAL].capability.extraFlags & caps.GeneralExtraFlag.ENC_SALTED_CHECKSUM)
+        
        self.sendConfirmActivePDU()
        #send synchronize
        self.sendClientFinalizeSynchronizePDU()
@@ -312,7 +315,7 @@ class Client(PDULayer):
        generalCapability = self._clientCapabilities[caps.CapsType.CAPSTYPE_GENERAL].capability
        generalCapability.osMajorType.value = caps.MajorType.OSMAJORTYPE_WINDOWS
        generalCapability.osMinorType.value = caps.MinorType.OSMINORTYPE_WINDOWS_NT
-        generalCapability.extraFlags.value = caps.GeneralExtraFlag.LONG_CREDENTIALS_SUPPORTED | caps.GeneralExtraFlag.NO_BITMAP_COMPRESSION_HDR
+        generalCapability.extraFlags.value = caps.GeneralExtraFlag.LONG_CREDENTIALS_SUPPORTED | caps.GeneralExtraFlag.NO_BITMAP_COMPRESSION_HDR | caps.GeneralExtraFlag.ENC_SALTED_CHECKSUM
        if not self._fastPathSender is None:
            generalCapability.extraFlags.value |= caps.GeneralExtraFlag.FASTPATH_OUTPUT_SUPPORTED
        
@@ -413,6 +416,9 @@ class Server(PDULayer):
        #find use full flag
        self._clientFastPathSupported = bool(self._clientCapabilities[caps.CapsType.CAPSTYPE_GENERAL].capability.extraFlags.value & caps.GeneralExtraFlag.FASTPATH_OUTPUT_SUPPORTED)
        
+        #secure checksum cap here maybe protocol (another) design error
+        self._transport._enableSecureCheckSum = bool(self._clientCapabilities[caps.CapsType.CAPSTYPE_GENERAL].capability.extraFlags & caps.GeneralExtraFlag.ENC_SALTED_CHECKSUM)
+        
        self.setNextState(self.recvClientSynchronizePDU)
        
    def recvClientSynchronizePDU(self, s):
@@ -525,7 +531,7 @@ class Server(PDULayer):
        generalCapability = self._serverCapabilities[caps.CapsType.CAPSTYPE_GENERAL].capability
        generalCapability.osMajorType.value = caps.MajorType.OSMAJORTYPE_WINDOWS
        generalCapability.osMinorType.value = caps.MinorType.OSMINORTYPE_WINDOWS_NT
-        generalCapability.extraFlags.value = caps.GeneralExtraFlag.LONG_CREDENTIALS_SUPPORTED | caps.GeneralExtraFlag.NO_BITMAP_COMPRESSION_HDR | caps.GeneralExtraFlag.FASTPATH_OUTPUT_SUPPORTED
+        generalCapability.extraFlags.value = caps.GeneralExtraFlag.LONG_CREDENTIALS_SUPPORTED | caps.GeneralExtraFlag.NO_BITMAP_COMPRESSION_HDR | caps.GeneralExtraFlag.FASTPATH_OUTPUT_SUPPORTED | caps.GeneralExtraFlag.ENC_SALTED_CHECKSUM
        
        inputCapability = self._serverCapabilities[caps.CapsType.CAPSTYPE_INPUT].capability
        inputCapability.inputFlags.value = caps.InputFlags.INPUT_FLAG_SCANCODES | caps.InputFlags.INPUT_FLAG_MOUSEX
--- a/rdpy/protocol/rdp/sec.py
+++ b/rdpy/protocol/rdp/sec.py
@@ -164,12 +164,12 @@ def macData(macSaltKey, data):
    md5Digest = md5.new()
    
    #encode length
-    s = Stream()
-    s.writeType(UInt32Le(len(data)))
+    dataLength = Stream()
+    dataLength.writeType(UInt32Le(len(data)))
    
    sha1Digest.update(macSaltKey)
    sha1Digest.update("\x36" * 40)
-    sha1Digest.update(s.getvalue())
+    sha1Digest.update(dataLength.getvalue())
    sha1Digest.update(data)
    
    sha1Sig = sha1Digest.digest()
@@ -180,6 +180,38 @@ def macData(macSaltKey, data):
    
    return md5Digest.digest()

+def macSaltedData(macSaltKey, data, encryptionCount):
+    """
+    @see: https://msdn.microsoft.com/en-us/library/cc240789.aspx
+    @param macSaltKey: {str} mac key
+    @param data: {str} data to sign
+    @param encryptionCount: nb encrypted packet
+    @return: {str} signature
+    """
+    sha1Digest = sha.new()
+    md5Digest = md5.new()
+    
+    #encode length
+    dataLengthS = Stream()
+    dataLengthS.writeType(UInt32Le(len(data)))
+    
+    encryptionCountS = Stream()
+    encryptionCountS.writeType(UInt32Le(encryptionCount))
+    
+    sha1Digest.update(macSaltKey)
+    sha1Digest.update("\x36" * 40)
+    sha1Digest.update(dataLengthS.getvalue())
+    sha1Digest.update(data)
+    sha1Digest.update(encryptionCountS.getvalue())
+    
+    sha1Sig = sha1Digest.digest()
+    
+    md5Digest.update(macSaltKey)
+    md5Digest.update("\x5c" * 48)
+    md5Digest.update(sha1Sig)
+    
+    return md5Digest.digest()
+
 def tempKey(initialKey, currentKey):
    """
    @see: http://msdn.microsoft.com/en-us/library/cc240792.aspx
@@ -342,6 +374,9 @@ class SecLayer(LayerAutomata, IStreamSender, tpkt.IFastPathListener, tpkt.IFastP
        #True if classic encryption is enable
        self._enableEncryption = False
        
+        #Enable Secure Mac generation
+        self._enableSecureCheckSum = False
+        
        #initialise decrypt and encrypt keys
        self._macKey = None
        self._initialDecrytKey = None
@@ -358,10 +393,11 @@ class SecLayer(LayerAutomata, IStreamSender, tpkt.IFastPathListener, tpkt.IFastP
        self._encryptRc4 = None
        
    
-    def readEncryptedPayload(self, s):
+    def readEncryptedPayload(self, s, saltedMacGeneration):
        """
        @summary: decrypt basic RDP security payload
        @param s: {Stream} encrypted stream
+        @param saltedMacGeneration: {bool} use salted mac generation
        @return: {Stream} decrypted
        """
        #if update is needed
@@ -378,18 +414,22 @@ class SecLayer(LayerAutomata, IStreamSender, tpkt.IFastPathListener, tpkt.IFastP
        decrypted = rc4.crypt(self._decryptRc4, encryptedPayload.value)

        #ckeck signature
-        if macData(self._macKey, decrypted)[:8] != signature.value:
-            raise InvalidExpectedDataException("Bad packet signature")
+        if not saltedMacGeneration and macData(self._macKey, decrypted)[:8] != signature.value:
+            raise InvalidExpectedDataException("bad signature")
+        
+        if saltedMacGeneration and macSaltedData(self._macKey, decrypted, self._nbDecryptedPacket)[:8] != signature.value:
+            raise InvalidExpectedDataException("bad signature")
        
        #count
        self._nbDecryptedPacket += 1

        return Stream(decrypted)
    
-    def writeEncryptedPayload(self, data):
+    def writeEncryptedPayload(self, data, saltedMacGeneration):
        """
        @summary: sign and crypt data
-        @param s: {Stream} raw stream
+        @param data: {Type} raw stream
+        @param saltedMacGeneration: {bool} use salted mac generation
        @return: {Tuple} (signature, encryptedData)
        """
        if self._nbEncryptedPacket == 4096:
@@ -400,9 +440,14 @@ class SecLayer(LayerAutomata, IStreamSender, tpkt.IFastPathListener, tpkt.IFastP
            self._nbEncryptedPacket = 0
            
        self._nbEncryptedPacket += 1
+        
        s = Stream()
        s.writeType(data)
-        return (String(macData(self._macKey, s.getvalue())[:8]), String(rc4.crypt(self._encryptRc4, s.getvalue())))
+        
+        if saltedMacGeneration:
+            return (String(macSaltedData(self._macKey, s.getvalue(), self._nbEncryptedPacket - 1)[:8]), String(rc4.crypt(self._encryptRc4, s.getvalue())))
+        else:
+            return (String(macData(self._macKey, s.getvalue())[:8]), String(rc4.crypt(self._encryptRc4, s.getvalue())))
    
    def recv(self, data):
        """
@@ -419,7 +464,7 @@ class SecLayer(LayerAutomata, IStreamSender, tpkt.IFastPathListener, tpkt.IFastP
        data.readType((securityFlag, securityFlagHi))
        
        if securityFlag.value & SecurityFlag.SEC_ENCRYPT:
-            data = self.readEncryptedPayload(data)
+            data = self.readEncryptedPayload(data, securityFlag.value & SecurityFlag.SEC_SECURE_CHECKSUM)
            
        self._presentation.recv(data)
        
@@ -433,7 +478,12 @@ class SecLayer(LayerAutomata, IStreamSender, tpkt.IFastPathListener, tpkt.IFastP
            self._transport.send(data)
            return
        
-        self.sendFlagged(SecurityFlag.SEC_ENCRYPT, data)
+        flag = SecurityFlag.SEC_ENCRYPT
+        
+        if self._enableSecureCheckSum:
+            flag |= SecurityFlag.SEC_SECURE_CHECKSUM
+        
+        self.sendFlagged(flag, data)
    
    def sendFlagged(self, flag, data):
        """
@@ -444,7 +494,7 @@ class SecLayer(LayerAutomata, IStreamSender, tpkt.IFastPathListener, tpkt.IFastP
        @param data: {Type | Tuple}
        """
        if flag & SecurityFlag.SEC_ENCRYPT:
-            data = self.writeEncryptedPayload(data)
+            data = self.writeEncryptedPayload(data, flag & SecurityFlag.SEC_SECURE_CHECKSUM)
        self._transport.send((UInt16Le(flag), UInt16Le(), data))
        
    def recvFastPath(self, secFlag, fastPathS):
@@ -454,7 +504,7 @@ class SecLayer(LayerAutomata, IStreamSender, tpkt.IFastPathListener, tpkt.IFastP
        @param fastPathS: {Stream}
        """
        if self._enableEncryption and secFlag & tpkt.SecFlags.FASTPATH_OUTPUT_ENCRYPTED:
-            fastPathS = self.readEncryptedPayload(fastPathS)
+            fastPathS = self.readEncryptedPayload(fastPathS, secFlag & tpkt.SecFlags.FASTPATH_OUTPUT_SECURE_CHECKSUM)
        
        self._fastPathPresentation.recvFastPath(secFlag, fastPathS)
        
@@ -472,7 +522,11 @@ class SecLayer(LayerAutomata, IStreamSender, tpkt.IFastPathListener, tpkt.IFastP
        """
        if self._enableEncryption:
            secFlag |= tpkt.SecFlags.FASTPATH_OUTPUT_ENCRYPTED
-            fastPathS = self.writeEncryptedPayload(fastPathS)
+            
+            if self._enableSecureCheckSum:
+                secFlag |= tpkt.SecFlags.FASTPATH_OUTPUT_SECURE_CHECKSUM
+                
+            fastPathS = self.writeEncryptedPayload(fastPathS, self._enableSecureCheckSum)
        
        self._fastPathTransport.sendFastPath(secFlag, fastPathS)
        
@@ -661,7 +715,7 @@ class Server(SecLayer):
            raise InvalidExpectedDataException("Waiting info packet")
        
        if securityFlag.value & SecurityFlag.SEC_ENCRYPT:
-            s = self.readEncryptedPayload(s)
+            s = self.readEncryptedPayload(s, securityFlag.value & SecurityFlag.SEC_SECURE_CHECKSUM)
        
        s.readType(self._info)
        #next state send error license