[mod_python] Re: Secure Sessions patch

Steve Holden steve at holdenweb.com
Mon Dec 18 13:11:51 EST 2006

Graham Dumpleton wrote:
> Daniel Adler wrote ..
>> Hi,
>> I saw there was a discussion on this topic already:
>> http://www.modpython.org/pipermail/mod_python/2006-May/021260.html
>> and came up with the same wish -
>> I want to force a session cookie to be explicitly created for https.
>> I have added a "secure" parameter to the session class constructors.
>> If it is set AND req.is_https(), the cookie will be created wiht "secure"
>> set.
>> A diff of session.py in release 3.2.10 with this feature is available on
>> http://neoscientists.org/~plex/mod_python_3_2_10_session_with_secure_cookie.diff
> I'd suggest that an explicit argument to Session.Session() is probably
> not the best way of doing this. I am also dubious of it only being set
> if HTTPS is used as that suggests that if first access is not via HTTPS,
> that one could then continue to access the site thereafter without it
> needing it to be HTTPS which defeats the purpose of having it in the
> first place as you want to probably force it to be HTTPS always and not
> allow HTTP at all.
> In place of an argument to Session.Session(), a PythonOption setting
> would possibly be more appropriate and would then be similar with how
> other aspects of cookies are configured for sessions. For example:
>   PythonOption mod_python.session.secure: 1
> By being an option it is easier to apply it to the complete URL
> namespace for an application, especially if application is coded poorly
> and doesn't have all session creation performed in one place only, or
> you can't modify the code for the application easily.
> In being set this way, 'secure' should also perhaps always be set,
> regardless of whether HTTPS is used. The outcome of this is that the
> client would never send the cookie back if it wasn't HTTPS, thus result
> would be always being pushed back to the login form (session creation
> point) if not HTTPS, thereby clearly indicating that something is wrong
> and also not inadvertently still letting someone in by accident through
> Another possible issue is whether through Session instance it should be
> possible to access the cookie properties and interrogate if the cookie
> for a session had the 'secure' attribute. If you don't have a means of
> validating that it was secure cookie, then someone could modify the
> cookie on the client side, remove the secure attribute and change from
> using HTTPS to HTTP and possibly start to reveal information in traffic
> that you didn't want to be revealed.
> On the latter point, one could argue that setting the PythonOption
> should also be a trigger for the Session class to perform a validation
> and always reject any cookie that doesn't have the 'secure' flag,
> presuming that the 'secure' flag is actually sent back with the cookie
> by the client.
I understood that browsers would flag cookies as secure if they received 
them over https, and maintain separation between secure and non-secure 
cookies. I wouldn't expect to see the secure flag represented inside the 
cookie, as the two sets (secure and non-secure) should be disjoint. This 
can cause session maintenance problems when some pages in the session 
are http and others are https.

> Thus, I can seem merit in what you are trying to achieve, but it perhaps
> needs some more thought as to how it should be achieved to ensure that
> there aren't back doors in the way it is done.
I agree that the proposed solution was a bit lame, though in the right 

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