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authorSenthil Kumaran <senthil@uthcode.com>2016-07-31 06:24:16 (GMT)
committerSenthil Kumaran <senthil@uthcode.com>2016-07-31 06:24:16 (GMT)
commit4cbb23f8f278fd1f71dcd5968aa0b3f0b4f3bd5d (patch)
tree6b9afcfb2dbbcaba109a7b00785f711af576c538
parentd27a7c1f22b263a3eef5d380c7058c993bd3a451 (diff)
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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 RĂ©mi Rampin.
-rw-r--r--Doc/howto/urllib2.rst5
-rw-r--r--Doc/library/urllib.request.rst13
-rw-r--r--Lib/test/test_urllib.py13
-rw-r--r--Lib/urllib/request.py7
-rw-r--r--Misc/NEWS4
5 files changed, 42 insertions, 0 deletions
diff --git a/Doc/howto/urllib2.rst b/Doc/howto/urllib2.rst
index 5a22660..cc0d85e 100644
--- a/Doc/howto/urllib2.rst
+++ b/Doc/howto/urllib2.rst
@@ -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
==================
diff --git a/Doc/library/urllib.request.rst b/Doc/library/urllib.request.rst
index 6493a29..f4f8692 100644
--- a/Doc/library/urllib.request.rst
+++ b/Doc/library/urllib.request.rst
@@ -161,6 +161,14 @@ 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:
@@ -265,6 +273,11 @@ 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()
diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index 2dec4e9..3b87fa3 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -194,6 +194,19 @@ 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):
"""Test urlopen() opening a fake http connection."""
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index ef62acc..537b765 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -2366,6 +2366,13 @@ 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):
diff --git a/Misc/NEWS b/Misc/NEWS
index ef5bdc8..e9a8f28 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -29,6 +29,10 @@ 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.
+
- Issue #24521: Fix possible integer overflows in the pickle module.
- Issue #22931: Allow '[' and ']' in cookie values.