Handle the case when received data is in wrong encoding (not utf-8).

ssh-audit.py

@@ -1657,7 +1657,10 @@ def audit(conf, sshv=None):
 	if err is None:
 		packet_type, payload = s.read_packet(sshv)
 		if packet_type < 0:
-			payload = payload.decode('utf-8') if payload else u'empty'
+			try:
+				payload = payload.decode('utf-8') if payload else u'empty'
+			except UnicodeDecodeError:
+				payload = u'"{0}"'.format(repr(payload).lstrip('b')[1:-1])
 			if payload == u'Protocol major versions differ.':
 				if sshv == 2 and conf.ssh1:
 					audit(conf, 1)

test/test_errors.py

@@ -81,6 +81,18 @@ class TestErrors(object):
 		assert 'error reading packet' in lines[-1]
 		assert 'xxx' in lines[-1]
 	
+	def test_nonutf8_data_after_banner(self, output_spy, virtual_socket):
+		vsocket = virtual_socket
+		vsocket.rdata.append(b'SSH-2.0-ssh-audit-test\r\n')
+		vsocket.rdata.append(b'\x81\xff\n')
+		output_spy.begin()
+		with pytest.raises(SystemExit):
+			self.audit(self._conf())
+		lines = output_spy.flush()
+		assert len(lines) == 2
+		assert 'error reading packet' in lines[-1]
+		assert '\\x81\\xff' in lines[-1]
+	
 	def test_protocol_mismatch_by_conf(self, output_spy, virtual_socket):
 		vsocket = virtual_socket
 		vsocket.rdata.append(b'SSH-1.3-ssh-audit-test\r\n')