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Diffstat (limited to 'docs/releases')
| -rw-r--r-- | docs/releases/1.8.10.txt | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/docs/releases/1.8.10.txt b/docs/releases/1.8.10.txt index 73c7cc04a4..d57afc470d 100644 --- a/docs/releases/1.8.10.txt +++ b/docs/releases/1.8.10.txt @@ -22,6 +22,39 @@ redirecting to this URL sends the user to ``attacker.com``. Also, if a developer relies on ``is_safe_url()`` to provide safe redirect targets and puts such a URL into a link, they could suffer from an XSS attack. +CVE-2016-2513: User enumeration through timing difference on password hasher work factor upgrade +================================================================================================ + +In each major version of Django since 1.6, the default number of iterations for +the ``PBKDF2PasswordHasher`` and its subclasses has increased. This improves +the security of the password as the speed of hardware increases, however, it +also creates a timing difference between a login request for a user with a +password encoded in an older number of iterations and login request for a +nonexistent user (which runs the default hasher's default number of iterations +since Django 1.6). + +This only affects users who haven't logged in since the iterations were +increased. The first time a user logs in after an iterations increase, their +password is updated with the new iterations and there is no longer a timing +difference. + +The new ``BasePasswordHasher.harden_runtime()`` method allows hashers to bridge +the runtime gap between the work factor (e.g. iterations) supplied in existing +encoded passwords and the default work factor of the hasher. This method +is implemented for ``PBKDF2PasswordHasher`` and ``BCryptPasswordHasher``. +The number of rounds for the latter hasher hasn't changed since Django 1.4, but +some projects may subclass it and increase the work factor as needed. + +A warning will be emitted for any :ref:`third-party password hashers that don't +implement <write-your-own-password-hasher>` a ``harden_runtime()`` method. + +If you have different password hashes in your database (such as SHA1 hashes +from users who haven't logged in since the default hasher switched to PBKDF2 +in Django 1.4), the timing difference on a login request for these users may be +even greater and this fix doesn't remedy that difference (or any difference +when changing hashers). You may be able to :ref:`upgrade those hashes +<wrapping-password-hashers>` to prevent a timing attack for that case. + Bugfixes ======== |