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commit 5d8645857936c142a3973694799c52165e2bdcdb
Author: Michael Manfre <mike@manfre.net>
Date: Fri Jun 14 22:12:58 2024 -0400
Fixed CVE-2024-39329 -- Standarized timing of verify_password() when checking unusuable passwords.
Refs #20760.
Thanks Michael Manfre for the fix and to Adam Johnson for the review.
diff --git a/django/contrib/auth/hashers.py b/django/contrib/auth/hashers.py
index 86ae7f42a..ee81b641d 100644
--- a/django/contrib/auth/hashers.py
+++ b/django/contrib/auth/hashers.py
@@ -36,14 +36,20 @@ def check_password(password, encoded, setter=None, preferred='default'):
If setter is specified, it'll be called when you need to
regenerate the password.
"""
- if password is None or not is_password_usable(encoded):
- return False
+ fake_runtime = password is None or not is_password_usable(encoded)
preferred = get_hasher(preferred)
try:
hasher = identify_hasher(encoded)
except ValueError:
# encoded is gibberish or uses a hasher that's no longer installed.
+ fake_runtime = True
+
+ if fake_runtime:
+ # Run the default password hasher once to reduce the timing difference
+ # between an existing user with an unusable password and a nonexistent
+ # user or missing hasher (similar to #20760).
+ make_password(get_random_string(UNUSABLE_PASSWORD_SUFFIX_LENGTH))
return False
hasher_changed = hasher.algorithm != preferred.algorithm
diff --git a/tests/auth_tests/test_hashers.py b/tests/auth_tests/test_hashers.py
index 8bc61bc8b..a1ae9400e 100644
--- a/tests/auth_tests/test_hashers.py
+++ b/tests/auth_tests/test_hashers.py
@@ -474,6 +474,38 @@ class TestUtilsHashPass(SimpleTestCase):
check_password('wrong_password', encoded)
self.assertEqual(hasher.harden_runtime.call_count, 1)
+ def test_check_password_calls_make_password_to_fake_runtime(self):
+ hasher = get_hasher("default")
+ cases = [
+ (None, None, None), # no plain text password provided
+ ("foo", make_password(password=None), None), # unusable encoded
+ ("letmein", make_password(password="letmein"), ValueError), # valid encoded
+ ]
+ for password, encoded, hasher_side_effect in cases:
+ with (
+ self.subTest(encoded=encoded),
+ mock.patch(
+ "django.contrib.auth.hashers.identify_hasher",
+ side_effect=hasher_side_effect,
+ ) as mock_identify_hasher,
+ mock.patch(
+ "django.contrib.auth.hashers.make_password"
+ ) as mock_make_password,
+ mock.patch(
+ "django.contrib.auth.hashers.get_random_string",
+ side_effect=lambda size: "x" * size,
+ ),
+ mock.patch.object(hasher, "verify"),
+ ):
+ # Ensure make_password is called to standardize timing.
+ check_password(password, encoded)
+ self.assertEqual(hasher.verify.call_count, 0)
+ self.assertEqual(mock_identify_hasher.mock_calls, [mock.call(encoded)])
+ self.assertEqual(
+ mock_make_password.mock_calls,
+ [mock.call("x" * UNUSABLE_PASSWORD_SUFFIX_LENGTH)],
+ )
+
class BasePasswordHasherTests(SimpleTestCase):
not_implemented_msg = 'subclasses of BasePasswordHasher must provide %s() method'
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