Fixed #26187 -- Removed weak password hashers from PASSWORD_HASHERS.

3 files changed, 100 insertions, 28 deletions

diff --git a/docs/ref/settings.txt b/docs/ref/settings.txt
index ab710fffac..47024514ca 100644
--- a/docs/ref/settings.txt
+++ b/docs/ref/settings.txt
@@ -2686,13 +2686,22 @@ Default::
         'django.contrib.auth.hashers.PBKDF2SHA1PasswordHasher',
         'django.contrib.auth.hashers.BCryptSHA256PasswordHasher',
         'django.contrib.auth.hashers.BCryptPasswordHasher',
-        'django.contrib.auth.hashers.SHA1PasswordHasher',
-        'django.contrib.auth.hashers.MD5PasswordHasher',
-        'django.contrib.auth.hashers.UnsaltedSHA1PasswordHasher',
-        'django.contrib.auth.hashers.UnsaltedMD5PasswordHasher',
-        'django.contrib.auth.hashers.CryptPasswordHasher',
     ]
 
+.. versionchanged:: 1.10
+
+    The following hashers were removed from the defaults::
+
+        'django.contrib.auth.hashers.SHA1PasswordHasher'
+        'django.contrib.auth.hashers.MD5PasswordHasher'
+        'django.contrib.auth.hashers.UnsaltedSHA1PasswordHasher'
+        'django.contrib.auth.hashers.UnsaltedMD5PasswordHasher'
+        'django.contrib.auth.hashers.CryptPasswordHasher'
+
+    Consider using a :ref:`wrapped password hasher <wrapping-password-hashers>`
+    to strengthen the hashes in your database. If that's not feasible, add this
+    setting to your project and add back any hashers that you need.
+
 .. setting:: AUTH_PASSWORD_VALIDATORS
 
 ``AUTH_PASSWORD_VALIDATORS``
diff --git a/docs/releases/1.10.txt b/docs/releases/1.10.txt
index b3f14731d3..db6b730670 100644
--- a/docs/releases/1.10.txt
+++ b/docs/releases/1.10.txt
@@ -502,6 +502,50 @@ In older versions, assigning ``None`` to a non-nullable ``ForeignKey`` or
 not allow null values.')``. For consistency with other model fields which don't
 have a similar check, this check is removed.
 
+Removed weak password hashers from the default ``PASSWORD_HASHERS`` setting
+---------------------------------------------------------------------------
+
+Django 0.90 stored passwords as unsalted MD5. Django 0.91 added support for
+salted SHA1 with automatic upgrade of passwords when a user logs in. Django 1.4
+added PBKDF2 as the default password hasher.
+
+If you have an old Django project with MD5 or SHA1 (even salted) encoded
+passwords, be aware that these can be cracked fairly easily with today's
+hardware. To make Django users acknowledge continued use of weak hashers, the
+following hashers are removed from the default :setting:`PASSWORD_HASHERS`
+setting::
+
+    'django.contrib.auth.hashers.SHA1PasswordHasher'
+    'django.contrib.auth.hashers.MD5PasswordHasher'
+    'django.contrib.auth.hashers.UnsaltedSHA1PasswordHasher'
+    'django.contrib.auth.hashers.UnsaltedMD5PasswordHasher'
+    'django.contrib.auth.hashers.CryptPasswordHasher'
+
+Consider using a :ref:`wrapped password hasher <wrapping-password-hashers>` to
+strengthen the hashes in your database. If that's not feasible, add the
+:setting:`PASSWORD_HASHERS` setting to your project and add back any hashers
+that you need.
+
+You can check if your database has any of the removed hashers like this::
+
+    from django.contrib.auth import get_user_model
+    User = get_user_model()
+
+    # Unsalted MD5/SHA1:
+    User.objects.filter(password__startswith='md5$$')
+    User.objects.filter(password__startswith='sha1$$')
+    # Salted MD5/SHA1:
+    User.objects.filter(password__startswith='md5$').exclude(password__startswith='md5$$')
+    User.objects.filter(password__startswith='sha1$').exclude(password__startswith='sha1$$')
+    # Crypt hasher:
+    User.objects.filter(password__startswith='crypt$$')
+
+    from django.db.models import CharField
+    from django.db.models.functions import Length
+    CharField.register_lookup(Length)
+    # Unsalted MD5 passwords might not have an 'md5$$' prefix:
+    User.objects.filter(password__length=32)
+
 Miscellaneous
 -------------
 
diff --git a/docs/topics/auth/passwords.txt b/docs/topics/auth/passwords.txt
index 17d47d8a0b..ecddeddbfa 100644
--- a/docs/topics/auth/passwords.txt
+++ b/docs/topics/auth/passwords.txt
@@ -62,15 +62,13 @@ The default for :setting:`PASSWORD_HASHERS` is::
         'django.contrib.auth.hashers.PBKDF2SHA1PasswordHasher',
         'django.contrib.auth.hashers.BCryptSHA256PasswordHasher',
         'django.contrib.auth.hashers.BCryptPasswordHasher',
-        'django.contrib.auth.hashers.SHA1PasswordHasher',
-        'django.contrib.auth.hashers.MD5PasswordHasher',
-        'django.contrib.auth.hashers.CryptPasswordHasher',
     ]
 
-This means that Django will use PBKDF2_ to store all passwords, but will support
-checking passwords stored with PBKDF2SHA1, bcrypt_, SHA1_, etc. The next few
-sections describe a couple of common ways advanced users may want to modify this
-setting.
+This means that Django will use PBKDF2_ to store all passwords but will support
+checking passwords stored with PBKDF2SHA1 and bcrypt_.
+
+The next few sections describe a couple of common ways advanced users may want
+to modify this setting.
 
 .. _bcrypt_usage:
 
@@ -96,13 +94,10 @@ To use Bcrypt as your default storage algorithm, do the following:
             'django.contrib.auth.hashers.BCryptPasswordHasher',
             'django.contrib.auth.hashers.PBKDF2PasswordHasher',
             'django.contrib.auth.hashers.PBKDF2SHA1PasswordHasher',
-            'django.contrib.auth.hashers.SHA1PasswordHasher',
-            'django.contrib.auth.hashers.MD5PasswordHasher',
-            'django.contrib.auth.hashers.CryptPasswordHasher',
         ]
 
-   (You need to keep the other entries in this list, or else Django won't
-   be able to upgrade passwords; see below).
+   Keep and/or add any entries in this list if you need Django to :ref:`upgrade
+   passwords <password-upgrades>`.
 
 That's it -- now your Django install will use Bcrypt as the default storage
 algorithm.
@@ -168,12 +163,8 @@ default PBKDF2 algorithm:
             'django.contrib.auth.hashers.PBKDF2SHA1PasswordHasher',
             'django.contrib.auth.hashers.BCryptSHA256PasswordHasher',
             'django.contrib.auth.hashers.BCryptPasswordHasher',
-            'django.contrib.auth.hashers.SHA1PasswordHasher',
-            'django.contrib.auth.hashers.MD5PasswordHasher',
-            'django.contrib.auth.hashers.CryptPasswordHasher',
         ]
 
-
 That's it -- now your Django install will use more iterations when it
 stores passwords using PBKDF2.
 
@@ -288,6 +279,37 @@ Include any other hashers that your site uses in this list.
 .. _bcrypt: https://en.wikipedia.org/wiki/Bcrypt
 .. _`bcrypt library`: https://pypi.python.org/pypi/bcrypt/
 
+.. _auth-included-hashers:
+
+Included hashers
+----------------
+
+The full list of hashers included in Django is::
+
+    [
+        'django.contrib.auth.hashers.PBKDF2PasswordHasher',
+        'django.contrib.auth.hashers.PBKDF2SHA1PasswordHasher',
+        'django.contrib.auth.hashers.BCryptSHA256PasswordHasher',
+        'django.contrib.auth.hashers.BCryptPasswordHasher',
+        'django.contrib.auth.hashers.SHA1PasswordHasher',
+        'django.contrib.auth.hashers.MD5PasswordHasher',
+        'django.contrib.auth.hashers.UnsaltedSHA1PasswordHasher',
+        'django.contrib.auth.hashers.UnsaltedMD5PasswordHasher',
+        'django.contrib.auth.hashers.CryptPasswordHasher',
+    ]
+
+The corresponding algorithm names are:
+
+* ``pbkdf2_sha256``
+* ``pbkdf2_sha1``
+* ``bcrypt_sha256``
+* ``bcrypt``
+* ``sha1``
+* ``md5``
+* ``unsalted_sha1``
+* ``unsalted_md5``
+* ``crypt``
+
 Manually managing a user's password
 ===================================
 
@@ -311,13 +333,10 @@ from the ``User`` model.
     Creates a hashed password in the format used by this application. It takes
     one mandatory argument: the password in plain-text. Optionally, you can
     provide a salt and a hashing algorithm to use, if you don't want to use the
-    defaults (first entry of ``PASSWORD_HASHERS`` setting).
-    Currently supported algorithms are: ``'pbkdf2_sha256'``, ``'pbkdf2_sha1'``,
-    ``'bcrypt_sha256'`` (see :ref:`bcrypt_usage`), ``'bcrypt'``, ``'sha1'``,
-    ``'md5'``, ``'unsalted_md5'`` (only for backward compatibility) and ``'crypt'``
-    if you have the ``crypt`` library installed. If the password argument is
-    ``None``, an unusable password is returned (a one that will be never
-    accepted by :func:`check_password`).
+    defaults (first entry of ``PASSWORD_HASHERS`` setting). See
+    :ref:`auth-included-hashers` for the algorithm name of each hasher. If the
+    password argument is ``None``, an unusable password is returned (a one that
+    will be never accepted by :func:`check_password`).
 
 .. function:: is_password_usable(encoded_password)