From c3188340e841633924e8ab7a055c1df0dffed9c1 Mon Sep 17 00:00:00 2001 From: Michael Merickel Date: Sun, 16 Sep 2018 11:06:05 -0500 Subject: deprecate pickleable sessions, recommend json --- docs/api/session.rst | 2 ++ docs/narr/sessions.rst | 72 +++++++++++++++++++++++++++++++++++++------------- 2 files changed, 55 insertions(+), 19 deletions(-) (limited to 'docs') diff --git a/docs/api/session.rst b/docs/api/session.rst index 53bae7c52..e0d2db726 100644 --- a/docs/api/session.rst +++ b/docs/api/session.rst @@ -17,3 +17,5 @@ .. autoclass:: PickleSerializer + .. autoclass:: JSONSerializer + diff --git a/docs/narr/sessions.rst b/docs/narr/sessions.rst index 2d80b1a63..17e8291a0 100644 --- a/docs/narr/sessions.rst +++ b/docs/narr/sessions.rst @@ -59,25 +59,59 @@ using the :meth:`pyramid.config.Configurator.set_session_factory` method. By default the :func:`~pyramid.session.SignedCookieSessionFactory` implementation contains the following security concerns: - - Session data is *unencrypted*. You should not use it when you keep - sensitive information in the session object, as the information can be - easily read by both users of your application and third parties who have - access to your users' network traffic. - - - If you use this sessioning implementation, and you inadvertently create a - cross-site scripting vulnerability in your application, because the - session data is stored unencrypted in a cookie, it will also be easier for - evildoers to obtain the current user's cross-site scripting token. - - - The default serialization method, while replaceable with something like - JSON, is implemented using pickle which can lead to remote code execution - if your secret key is compromised. - - In short, use a different session factory implementation (preferably one - which keeps session data on the server) for anything but the most basic of - applications where "session security doesn't matter", you are sure your - application has no cross-site scripting vulnerabilities, and you are confident - your secret key will not be exposed. + - Session data is *unencrypted* (but it is signed / authenticated). + + This means an attacker cannot change the session data, but they can view it. + You should not use it when you keep sensitive information in the session object, as the information can be easily read by both users of your application and third parties who have access to your users' network traffic. + + At the very least, use TLS and set ``secure=True`` to avoid arbitrary users on the network from viewing the session contents. + + - If you use this sessioning implementation, and you inadvertently create a cross-site scripting vulnerability in your application, because the session data is stored unencrypted in a cookie, it will also be easier for evildoers to obtain the current user's cross-site scripting token. + + Set ``httponly=True`` to mitigate this vulnerability by hiding the cookie from client-side JavaScript. + + - The default serialization method, while replaceable with something like JSON, is implemented using pickle which can lead to remote code execution if your secret key is compromised. + + To mitigate this, set ``serializer=pyramid.session.JSONSerializer()`` to use :class:`pyramid.session.JSONSerializer`. This option will be the default in :app:`Pyramid` 2.0. + See :ref:`pickle_session_deprecation` for more information about this change. + + In short, use a different session factory implementation (preferably one which keeps session data on the server) for anything but the most basic of applications where "session security doesn't matter", you are sure your application has no cross-site scripting vulnerabilities, and you are confident your secret key will not be exposed. + +.. _pickle_session_deprecation: + +Upcoming Changes to ISession in Pyramid 2.0 +------------------------------------------- + +In :app:`Pyramid` 2.0 the :class:`pyramid.interfaces.ISession` interface will be changing to require that session implementations only need to support json-serializable data types. +This is a stricter contract than the current requirement that all objects be pickleable and it is being done for security purposes. +This is a backward-incompatible change. +Currently, if a client-side session implementation is compromised, it leaves the application vulnerable to remote code execution attacks using specially-crafted sessions that execute code when deserialized. + +For users with compatibility concerns, it's possible to craft a serializer that can handle both formats until you are satisfied that clients have had time to reasonably upgrade. +Remember that sessions should be short-lived and thus the number of clients affected should be small (no longer than an auth token, at a maximum). An example serializer: + +.. code-block:: python + :linenos: + + from pyramid.session import JSONSerializer + from pyramid.session import PickleSerializer + + class JSONSerializerWithPickleFallback(object): + def __init__(self): + self.json = JSONSerializer() + self.pickle = PickleSerializer() + + def dumps(self, value): + # maybe catch serialization errors here and keep using pickle + # while finding spots in your app that are not storing + # json-serializable objects, falling back to pickle + return self.json.dumps(value) + + def loads(self, value): + try: + return self.json.loads(value) + except ValueError: + return self.pickle.loads(value) .. index:: single: session object -- cgit v1.2.3 From ba5ca651c2cba9e45c80e0fb0ed6c6408ea3e042 Mon Sep 17 00:00:00 2001 From: Michael Merickel Date: Sun, 16 Sep 2018 11:35:49 -0500 Subject: deprecate signed_serialize and signed_deserialize --- docs/api/session.rst | 6 ------ 1 file changed, 6 deletions(-) (limited to 'docs') diff --git a/docs/api/session.rst b/docs/api/session.rst index e0d2db726..d0cb112ec 100644 --- a/docs/api/session.rst +++ b/docs/api/session.rst @@ -5,14 +5,8 @@ .. automodule:: pyramid.session - .. autofunction:: signed_serialize - - .. autofunction:: signed_deserialize - .. autofunction:: SignedCookieSessionFactory - .. autofunction:: UnencryptedCookieSessionFactoryConfig - .. autofunction:: BaseCookieSessionFactory .. autoclass:: PickleSerializer -- cgit v1.2.3 From 38bbea331f9c485d40892a17674272a8876a55a1 Mon Sep 17 00:00:00 2001 From: Michael Merickel Date: Sun, 16 Sep 2018 15:43:43 -0500 Subject: tweak some docs --- docs/narr/sessions.rst | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'docs') diff --git a/docs/narr/sessions.rst b/docs/narr/sessions.rst index 17e8291a0..971b4502d 100644 --- a/docs/narr/sessions.rst +++ b/docs/narr/sessions.rst @@ -79,10 +79,13 @@ using the :meth:`pyramid.config.Configurator.set_session_factory` method. .. _pickle_session_deprecation: +.. index:: + triple: pickle deprecation; JSON-serializable; ISession interface + Upcoming Changes to ISession in Pyramid 2.0 ------------------------------------------- -In :app:`Pyramid` 2.0 the :class:`pyramid.interfaces.ISession` interface will be changing to require that session implementations only need to support json-serializable data types. +In :app:`Pyramid` 2.0 the :class:`pyramid.interfaces.ISession` interface will be changing to require that session implementations only need to support JSON-serializable data types. This is a stricter contract than the current requirement that all objects be pickleable and it is being done for security purposes. This is a backward-incompatible change. Currently, if a client-side session implementation is compromised, it leaves the application vulnerable to remote code execution attacks using specially-crafted sessions that execute code when deserialized. @@ -104,7 +107,7 @@ Remember that sessions should be short-lived and thus the number of clients affe def dumps(self, value): # maybe catch serialization errors here and keep using pickle # while finding spots in your app that are not storing - # json-serializable objects, falling back to pickle + # JSON-serializable objects, falling back to pickle return self.json.dumps(value) def loads(self, value): @@ -173,7 +176,7 @@ Some gotchas: that they are instances of basic types of objects, such as strings, lists, dictionaries, tuples, integers, etc. If you place an object in a session data key or value that is not pickleable, an error will be raised when the - session is serialized. + session is serialized. Please also see :ref:`pickle_session_deprecation`. - If you place a mutable value (for example, a list or a dictionary) in a session object, and you subsequently mutate that value, you must call the -- cgit v1.2.3 From 07207637818049d27abb90792d48d7ed8fdd2340 Mon Sep 17 00:00:00 2001 From: Michael Merickel Date: Sun, 16 Sep 2018 22:45:05 -0500 Subject: ref after index apparently --- docs/narr/sessions.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'docs') diff --git a/docs/narr/sessions.rst b/docs/narr/sessions.rst index 971b4502d..d4d3c1074 100644 --- a/docs/narr/sessions.rst +++ b/docs/narr/sessions.rst @@ -77,11 +77,11 @@ using the :meth:`pyramid.config.Configurator.set_session_factory` method. In short, use a different session factory implementation (preferably one which keeps session data on the server) for anything but the most basic of applications where "session security doesn't matter", you are sure your application has no cross-site scripting vulnerabilities, and you are confident your secret key will not be exposed. -.. _pickle_session_deprecation: - .. index:: triple: pickle deprecation; JSON-serializable; ISession interface +.. _pickle_session_deprecation: + Upcoming Changes to ISession in Pyramid 2.0 ------------------------------------------- -- cgit v1.2.3 From 97ee7f3aa8af74a01e51c0c14fda1c0a5a490663 Mon Sep 17 00:00:00 2001 From: Michael Merickel Date: Tue, 25 Sep 2018 15:49:23 -0500 Subject: show how to use the serializer --- docs/narr/sessions.rst | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'docs') diff --git a/docs/narr/sessions.rst b/docs/narr/sessions.rst index d4d3c1074..ded7e87e3 100644 --- a/docs/narr/sessions.rst +++ b/docs/narr/sessions.rst @@ -98,6 +98,7 @@ Remember that sessions should be short-lived and thus the number of clients affe from pyramid.session import JSONSerializer from pyramid.session import PickleSerializer + from pyramid.session import SignedCookieSessionFactory class JSONSerializerWithPickleFallback(object): def __init__(self): @@ -116,6 +117,11 @@ Remember that sessions should be short-lived and thus the number of clients affe except ValueError: return self.pickle.loads(value) + # somewhere in your configuration code + serializer = JSONSerializerWithPickleFallback() + session_factory = SignedCookieSessionFactory(..., serializer=serializer) + config.set_session_factory(session_factory) + .. index:: single: session object -- cgit v1.2.3