[merge from 3.3] 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 #27568 Reported and patch contributed by Rémi Rampin.
This commit is contained in:
Senthil Kumaran 2016-07-30 23:34:34 -07:00
commit 436fe5a447
5 changed files with 42 additions and 0 deletions

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@ -538,6 +538,11 @@ setting up a `Basic Authentication`_ handler: ::
through a proxy. However, this can be enabled by extending urllib.request as
shown in the recipe [#]_.
.. note::
`HTTP_PROXY`` will be ignored if a variable ``REQUEST_METHOD`` is set; see
the documentation on :func:`~urllib.request.getproxies`.
Sockets and Layers
==================

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@ -166,6 +166,14 @@ The :mod:`urllib.request` module defines the following functions:
cannot find it, looks for proxy information from Mac OSX System
Configuration for Mac OS X and Windows Systems Registry for Windows.
.. note::
If the environment variable ``REQUEST_METHOD`` is set, which usually
indicates your script is running in a CGI environment, the environment
variable ``HTTP_PROXY`` (uppercase ``_PROXY``) will be ignored. This is
because that variable can be injected by a client using the "Proxy:" HTTP
header. If you need to use an HTTP proxy in a CGI environment use
``ProxyHandler`` explicitly.
The following classes are provided:
@ -268,6 +276,11 @@ The following classes are provided:
To disable autodetected proxy pass an empty dictionary.
.. note::
``HTTP_PROXY`` will be ignored if a variable ``REQUEST_METHOD`` is set;
see the documentation on :func:`~urllib.request.getproxies`.
.. class:: HTTPPasswordMgr()

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@ -222,6 +222,19 @@ class ProxyTests(unittest.TestCase):
self.env.set('NO_PROXY', 'localhost, anotherdomain.com, newdomain.com')
self.assertTrue(urllib.request.proxy_bypass_environment('anotherdomain.com'))
def test_proxy_cgi_ignore(self):
try:
self.env.set('HTTP_PROXY', 'http://somewhere:3128')
proxies = urllib.request.getproxies_environment()
self.assertEqual('http://somewhere:3128', proxies['http'])
self.env.set('REQUEST_METHOD', 'GET')
proxies = urllib.request.getproxies_environment()
self.assertNotIn('http', proxies)
finally:
self.env.unset('REQUEST_METHOD')
self.env.unset('HTTP_PROXY')
class urlopen_HttpTests(unittest.TestCase, FakeHTTPMixin, FakeFTPMixin):
"""Test urlopen() opening a fake http connection."""

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@ -2337,6 +2337,13 @@ def getproxies_environment():
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 'REQUEST_METHOD' in os.environ:
proxies.pop('http', None)
return proxies
def proxy_bypass_environment(host):

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@ -13,6 +13,10 @@ Core and Builtins
Library
-------
- Issue #27568: 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.
Tests
-----