Prevent HTTPoxy attack (CVE-2016-1000110)
Ignore the HTTP_PROXY variable when REQUEST_METHOD environment is set, which
indicates that the script is in CGI mode.
Issue reported and patch contributed by Rémi Rampin.
diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index 434d533..27a1d38 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -170,6 +170,18 @@
self.assertTrue(urllib.proxy_bypass_environment('anotherdomain.com:8888'))
self.assertTrue(urllib.proxy_bypass_environment('newdomain.com:1234'))
+ def test_proxy_cgi_ignore(self):
+ try:
+ self.env.set('HTTP_PROXY', 'http://somewhere:3128')
+ proxies = urllib.getproxies_environment()
+ self.assertEqual('http://somewhere:3128', proxies['http'])
+ self.env.set('REQUEST_METHOD', 'GET')
+ proxies = urllib.getproxies_environment()
+ self.assertNotIn('http', proxies)
+ finally:
+ self.env.unset('REQUEST_METHOD')
+ self.env.unset('HTTP_PROXY')
+
def test_proxy_bypass_environment_host_match(self):
bypass = urllib.proxy_bypass_environment
self.env.set('NO_PROXY',
diff --git a/Lib/urllib.py b/Lib/urllib.py
index 139fab9..c3ba2c9 100644
--- a/Lib/urllib.py
+++ b/Lib/urllib.py
@@ -1380,12 +1380,21 @@
If you need a different way, you can pass a proxies dictionary to the
[Fancy]URLopener constructor.
"""
+ # Get all variables
proxies = {}
for name, value in os.environ.items():
name = name.lower()
if value and name[-6:] == '_proxy':
proxies[name[:-6]] = value
+ # CVE-2016-1000110 - If we are running as CGI script, forget HTTP_PROXY
+ # (non-all-lowercase) as it may be set from the web server by a "Proxy:"
+ # header from the client
+ # If "proxy" is lowercase, it will still be used thanks to the next block
+ if 'REQUEST_METHOD' in os.environ:
+ proxies.pop('http', None)
+
+ # Get lowercase variables
for name, value in os.environ.items():
if name[-6:] == '_proxy':
name = name.lower()