From e717bb0335826dc7b760ae97c35848eb7ea5dcd5 Mon Sep 17 00:00:00 2001
From: Anders Kaseorg <andersk@mit.edu>
Date: Sun, 29 Nov 2020 01:16:14 -0800
Subject: [PATCH] Subclass pickle.Unpickler for security
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
---
invirt-vnc-client | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/invirt-vnc-client b/invirt-vnc-client
index b789c56..f71366a 100755
--- a/invirt-vnc-client
+++ b/invirt-vnc-client
@@ -3,6 +3,7 @@ from twisted.internet import reactor, ssl, protocol, error
from OpenSSL import SSL
import base64, pickle
import getopt, sys, os, time
+import io
verbose = False
@@ -122,6 +123,10 @@ class ProxyFactory(protocol.Factory):
self.authtoken = authtoken
self.machine = machine
+class SafeUnpickler(pickle.Unpickler):
+ def find_class(self, module, name):
+ raise pickle.UnpicklingError("globals are forbidden")
+
def main():
global verbose
try:
@@ -175,7 +180,7 @@ def main():
# Unpack authentication token
try:
- token_inner = pickle.loads(base64.urlsafe_b64decode((authtoken.split("."))[0]))
+ token_inner = SafeUnpickler(io.BytesIO(base64.urlsafe_b64decode((authtoken.split("."))[0]))).load()
machine = token_inner["machine"]
connect_host = token_inner["connect_host"]
connect_port = token_inner["connect_port"]
--
1.7.9.5