diff --git a/django/conf/urls/__init__.py b/django/conf/urls/__init__.py
index 04fb1dff59..c0340c0543 100644
--- a/django/conf/urls/__init__.py
+++ b/django/conf/urls/__init__.py
@@ -5,8 +5,9 @@ from django.utils.importlib import import_module
 from django.utils import six
 
 
-__all__ = ['handler403', 'handler404', 'handler500', 'include', 'patterns', 'url']
+__all__ = ['handler400', 'handler403', 'handler404', 'handler500', 'include', 'patterns', 'url']
 
+handler400 = 'django.views.defaults.bad_request'
 handler403 = 'django.views.defaults.permission_denied'
 handler404 = 'django.views.defaults.page_not_found'
 handler500 = 'django.views.defaults.server_error'
diff --git a/django/contrib/admin/exceptions.py b/django/contrib/admin/exceptions.py
new file mode 100644
index 0000000000..2e094c6da1
--- /dev/null
+++ b/django/contrib/admin/exceptions.py
@@ -0,0 +1,6 @@
+from django.core.exceptions import SuspiciousOperation
+
+
+class DisallowedModelAdminLookup(SuspiciousOperation):
+    """Invalid filter was passed to admin view via URL querystring"""
+    pass
diff --git a/django/contrib/admin/views/main.py b/django/contrib/admin/views/main.py
index 21ac30b7b3..dbed21265c 100644
--- a/django/contrib/admin/views/main.py
+++ b/django/contrib/admin/views/main.py
@@ -14,6 +14,7 @@ from django.utils.translation import ugettext, ugettext_lazy
 from django.utils.http import urlencode
 
 from django.contrib.admin import FieldListFilter
+from django.contrib.admin.exceptions import DisallowedModelAdminLookup
 from django.contrib.admin.options import IncorrectLookupParameters
 from django.contrib.admin.util import (quote, get_fields_from_path,
     lookup_needs_distinct, prepare_lookup_value)
@@ -128,7 +129,7 @@ class ChangeList(six.with_metaclass(RenameChangeListMethods)):
                 lookup_params[force_str(key)] = value
 
             if not self.model_admin.lookup_allowed(key, value):
-                raise SuspiciousOperation("Filtering by %s not allowed" % key)
+                raise DisallowedModelAdminLookup("Filtering by %s not allowed" % key)
 
         filter_specs = []
         if self.list_filter:
diff --git a/django/contrib/auth/tests/test_views.py b/django/contrib/auth/tests/test_views.py
index fe1d7fb52f..94cad90b15 100644
--- a/django/contrib/auth/tests/test_views.py
+++ b/django/contrib/auth/tests/test_views.py
@@ -10,7 +10,6 @@ from django.conf import global_settings, settings
 from django.contrib.sites.models import Site, RequestSite
 from django.contrib.auth.models import User
 from django.core import mail
-from django.core.exceptions import SuspiciousOperation
 from django.core.urlresolvers import reverse, NoReverseMatch
 from django.http import QueryDict, HttpRequest
 from django.utils.encoding import force_text
@@ -18,7 +17,7 @@ from django.utils.html import escape
 from django.utils.http import urlquote
 from django.utils._os import upath
 from django.test import TestCase
-from django.test.utils import override_settings
+from django.test.utils import override_settings, patch_logger
 from django.middleware.csrf import CsrfViewMiddleware
 from django.contrib.sessions.middleware import SessionMiddleware
 
@@ -155,23 +154,28 @@ class PasswordResetTest(AuthViewsTestCase):
         # produce a meaningful reset URL, we need to be certain that the
         # HTTP_HOST header isn't poisoned. This is done as a check when get_host()
         # is invoked, but we check here as a practical consequence.
-        with self.assertRaises(SuspiciousOperation):
-            self.client.post('/password_reset/',
-                {'email': 'staffmember@example.com'},
-                HTTP_HOST='www.example:dr.frankenstein@evil.tld'
-            )
-        self.assertEqual(len(mail.outbox), 0)
+        with patch_logger('django.security.DisallowedHost', 'error') as logger_calls:
+            response = self.client.post('/password_reset/',
+                    {'email': 'staffmember@example.com'},
+                    HTTP_HOST='www.example:dr.frankenstein@evil.tld'
+                )
+            self.assertEqual(response.status_code, 400)
+            self.assertEqual(len(mail.outbox), 0)
+            self.assertEqual(len(logger_calls), 1)
 
     # Skip any 500 handler action (like sending more mail...)
     @override_settings(DEBUG_PROPAGATE_EXCEPTIONS=True)
     def test_poisoned_http_host_admin_site(self):
         "Poisoned HTTP_HOST headers can't be used for reset emails on admin views"
-        with self.assertRaises(SuspiciousOperation):
-            self.client.post('/admin_password_reset/',
-                {'email': 'staffmember@example.com'},
-                HTTP_HOST='www.example:dr.frankenstein@evil.tld'
-            )
-        self.assertEqual(len(mail.outbox), 0)
+        with patch_logger('django.security.DisallowedHost', 'error') as logger_calls:
+            response = self.client.post('/admin_password_reset/',
+                    {'email': 'staffmember@example.com'},
+                    HTTP_HOST='www.example:dr.frankenstein@evil.tld'
+                )
+            self.assertEqual(response.status_code, 400)
+            self.assertEqual(len(mail.outbox), 0)
+            self.assertEqual(len(logger_calls), 1)
+
 
     def _test_confirm_start(self):
         # Start by creating the email
@@ -678,5 +682,7 @@ class ChangelistTests(AuthViewsTestCase):
         self.login()
 
         # A lookup that tries to filter on password isn't OK
-        with self.assertRaises(SuspiciousOperation):
+        with patch_logger('django.security.DisallowedModelAdminLookup', 'error') as logger_calls:
             response = self.client.get('/admin/auth/user/?password__startswith=sha1$')
+            self.assertEqual(response.status_code, 400)
+            self.assertEqual(len(logger_calls), 1)
diff --git a/django/contrib/formtools/exceptions.py b/django/contrib/formtools/exceptions.py
new file mode 100644
index 0000000000..f07ac9f745
--- /dev/null
+++ b/django/contrib/formtools/exceptions.py
@@ -0,0 +1,6 @@
+from django.core.exceptions import SuspiciousOperation
+
+
+class WizardViewCookieModified(SuspiciousOperation):
+    """Signature of cookie modified"""
+    pass
diff --git a/django/contrib/formtools/wizard/storage/cookie.py b/django/contrib/formtools/wizard/storage/cookie.py
index e80361042f..9bf6503f18 100644
--- a/django/contrib/formtools/wizard/storage/cookie.py
+++ b/django/contrib/formtools/wizard/storage/cookie.py
@@ -1,8 +1,8 @@
 import json
 
-from django.core.exceptions import SuspiciousOperation
 from django.core.signing import BadSignature
 
+from django.contrib.formtools.exceptions import WizardViewCookieModified
 from django.contrib.formtools.wizard import storage
 
 
@@ -21,7 +21,7 @@ class CookieStorage(storage.BaseStorage):
         except KeyError:
             data = None
         except BadSignature:
-            raise SuspiciousOperation('WizardView cookie manipulated')
+            raise WizardViewCookieModified('WizardView cookie manipulated')
         if data is None:
             return None
         return json.loads(data, cls=json.JSONDecoder)
diff --git a/django/contrib/sessions/backends/base.py b/django/contrib/sessions/backends/base.py
index f79a264500..759d7ac7ad 100644
--- a/django/contrib/sessions/backends/base.py
+++ b/django/contrib/sessions/backends/base.py
@@ -2,6 +2,8 @@ from __future__ import unicode_literals
 
 import base64
 from datetime import datetime, timedelta
+import logging
+
 try:
     from django.utils.six.moves import cPickle as pickle
 except ImportError:
@@ -14,7 +16,9 @@ from django.utils.crypto import constant_time_compare
 from django.utils.crypto import get_random_string
 from django.utils.crypto import salted_hmac
 from django.utils import timezone
-from django.utils.encoding import force_bytes
+from django.utils.encoding import force_bytes, force_text
+
+from django.contrib.sessions.exceptions import SuspiciousSession
 
 # session_key should not be case sensitive because some backends can store it
 # on case insensitive file systems.
@@ -94,12 +98,16 @@ class SessionBase(object):
             hash, pickled = encoded_data.split(b':', 1)
             expected_hash = self._hash(pickled)
             if not constant_time_compare(hash.decode(), expected_hash):
-                raise SuspiciousOperation("Session data corrupted")
+                raise SuspiciousSession("Session data corrupted")
             else:
                 return pickle.loads(pickled)
-        except Exception:
+        except Exception as e:
             # ValueError, SuspiciousOperation, unpickling exceptions. If any of
             # these happen, just return an empty dictionary (an empty session).
+            if isinstance(e, SuspiciousOperation):
+                logger = logging.getLogger('django.security.%s' %
+                        e.__class__.__name__)
+                logger.warning(force_text(e))
             return {}
 
     def update(self, dict_):
diff --git a/django/contrib/sessions/backends/cached_db.py b/django/contrib/sessions/backends/cached_db.py
index 31c6fbfce3..be22c1f97a 100644
--- a/django/contrib/sessions/backends/cached_db.py
+++ b/django/contrib/sessions/backends/cached_db.py
@@ -2,10 +2,13 @@
 Cached, database-backed sessions.
 """
 
+import logging
+
 from django.contrib.sessions.backends.db import SessionStore as DBStore
 from django.core.cache import cache
 from django.core.exceptions import SuspiciousOperation
 from django.utils import timezone
+from django.utils.encoding import force_text
 
 KEY_PREFIX = "django.contrib.sessions.cached_db"
 
@@ -41,7 +44,11 @@ class SessionStore(DBStore):
                 data = self.decode(s.session_data)
                 cache.set(self.cache_key, data,
                     self.get_expiry_age(expiry=s.expire_date))
-            except (Session.DoesNotExist, SuspiciousOperation):
+            except (Session.DoesNotExist, SuspiciousOperation) as e:
+                if isinstance(e, SuspiciousOperation):
+                    logger = logging.getLogger('django.security.%s' %
+                            e.__class__.__name__)
+                    logger.warning(force_text(e))
                 self.create()
                 data = {}
         return data
diff --git a/django/contrib/sessions/backends/db.py b/django/contrib/sessions/backends/db.py
index 30da0b7a10..206fca2700 100644
--- a/django/contrib/sessions/backends/db.py
+++ b/django/contrib/sessions/backends/db.py
@@ -1,8 +1,10 @@
+import logging
+
 from django.contrib.sessions.backends.base import SessionBase, CreateError
 from django.core.exceptions import SuspiciousOperation
 from django.db import IntegrityError, transaction, router
 from django.utils import timezone
-
+from django.utils.encoding import force_text
 
 class SessionStore(SessionBase):
     """
@@ -18,7 +20,11 @@ class SessionStore(SessionBase):
                 expire_date__gt=timezone.now()
             )
             return self.decode(s.session_data)
-        except (Session.DoesNotExist, SuspiciousOperation):
+        except (Session.DoesNotExist, SuspiciousOperation) as e:
+            if isinstance(e, SuspiciousOperation):
+                logger = logging.getLogger('django.security.%s' %
+                        e.__class__.__name__)
+                logger.warning(force_text(e))
             self.create()
             return {}
 
diff --git a/django/contrib/sessions/backends/file.py b/django/contrib/sessions/backends/file.py
index 3c3408e9a8..f47aa2d867 100644
--- a/django/contrib/sessions/backends/file.py
+++ b/django/contrib/sessions/backends/file.py
@@ -1,5 +1,6 @@
 import datetime
 import errno
+import logging
 import os
 import shutil
 import tempfile
@@ -8,6 +9,9 @@ from django.conf import settings
 from django.contrib.sessions.backends.base import SessionBase, CreateError, VALID_KEY_CHARS
 from django.core.exceptions import SuspiciousOperation, ImproperlyConfigured
 from django.utils import timezone
+from django.utils.encoding import force_text
+
+from django.contrib.sessions.exceptions import InvalidSessionKey
 
 class SessionStore(SessionBase):
     """
@@ -48,7 +52,7 @@ class SessionStore(SessionBase):
         # should always be md5s, so they should never contain directory
         # components.
         if not set(session_key).issubset(set(VALID_KEY_CHARS)):
-            raise SuspiciousOperation(
+            raise InvalidSessionKey(
                 "Invalid characters in session key")
 
         return os.path.join(self.storage_path, self.file_prefix + session_key)
@@ -75,7 +79,11 @@ class SessionStore(SessionBase):
             if file_data:
                 try:
                     session_data = self.decode(file_data)
-                except (EOFError, SuspiciousOperation):
+                except (EOFError, SuspiciousOperation) as e:
+                    if isinstance(e, SuspiciousOperation):
+                        logger = logging.getLogger('django.security.%s' %
+                                e.__class__.__name__)
+                        logger.warning(force_text(e))
                     self.create()
 
                 # Remove expired sessions.
diff --git a/django/contrib/sessions/exceptions.py b/django/contrib/sessions/exceptions.py
new file mode 100644
index 0000000000..4f4dc6b048
--- /dev/null
+++ b/django/contrib/sessions/exceptions.py
@@ -0,0 +1,11 @@
+from django.core.exceptions import SuspiciousOperation
+
+
+class InvalidSessionKey(SuspiciousOperation):
+    """Invalid characters in session key"""
+    pass
+
+
+class SuspiciousSession(SuspiciousOperation):
+    """The session may be tampered with"""
+    pass
diff --git a/django/contrib/sessions/tests.py b/django/contrib/sessions/tests.py
index 1a7286e77e..cd8191a6a4 100644
--- a/django/contrib/sessions/tests.py
+++ b/django/contrib/sessions/tests.py
@@ -1,3 +1,4 @@
+import base64
 from datetime import timedelta
 import os
 import shutil
@@ -15,14 +16,16 @@ from django.contrib.sessions.models import Session
 from django.contrib.sessions.middleware import SessionMiddleware
 from django.core.cache import get_cache
 from django.core import management
-from django.core.exceptions import ImproperlyConfigured, SuspiciousOperation
+from django.core.exceptions import ImproperlyConfigured
 from django.http import HttpResponse
 from django.test import TestCase, RequestFactory
-from django.test.utils import override_settings
+from django.test.utils import override_settings, patch_logger
 from django.utils import six
 from django.utils import timezone
 from django.utils import unittest
 
+from django.contrib.sessions.exceptions import InvalidSessionKey
+
 
 class SessionTestsMixin(object):
     # This does not inherit from TestCase to avoid any tests being run with this
@@ -272,6 +275,15 @@ class SessionTestsMixin(object):
         encoded = self.session.encode(data)
         self.assertEqual(self.session.decode(encoded), data)
 
+    def test_decode_failure_logged_to_security(self):
+        bad_encode = base64.b64encode(b'flaskdj:alkdjf')
+        with patch_logger('django.security.SuspiciousSession', 'warning') as calls:
+            self.assertEqual({}, self.session.decode(bad_encode))
+            # check that the failed decode is logged
+            self.assertEqual(len(calls), 1)
+            self.assertTrue('corrupted' in calls[0])
+
+
     def test_actual_expiry(self):
         # Regression test for #19200
         old_session_key = None
@@ -411,12 +423,12 @@ class FileSessionTests(SessionTestsMixin, unittest.TestCase):
         # This is tested directly on _key_to_file, as load() will swallow
         # a SuspiciousOperation in the same way as an IOError - by creating
         # a new session, making it unclear whether the slashes were detected.
-        self.assertRaises(SuspiciousOperation,
+        self.assertRaises(InvalidSessionKey,
                           self.backend()._key_to_file, "a\\b\\c")
 
     def test_invalid_key_forwardslash(self):
         # Ensure we don't allow directory-traversal
-        self.assertRaises(SuspiciousOperation,
+        self.assertRaises(InvalidSessionKey,
                           self.backend()._key_to_file, "a/b/c")
 
     @override_settings(SESSION_ENGINE="django.contrib.sessions.backends.file")
diff --git a/django/core/exceptions.py b/django/core/exceptions.py
index 233af40f88..2c79736e33 100644
--- a/django/core/exceptions.py
+++ b/django/core/exceptions.py
@@ -1,6 +1,7 @@
 """
 Global Django exception and warning classes.
 """
+import logging
 from functools import reduce
 
 
@@ -9,37 +10,56 @@ class DjangoRuntimeWarning(RuntimeWarning):
 
 
 class ObjectDoesNotExist(Exception):
-    "The requested object does not exist"
+    """The requested object does not exist"""
     silent_variable_failure = True
 
 
 class MultipleObjectsReturned(Exception):
-    "The query returned multiple objects when only one was expected."
+    """The query returned multiple objects when only one was expected."""
     pass
 
 
 class SuspiciousOperation(Exception):
-    "The user did something suspicious"
+    """The user did something suspicious"""
+
+
+class SuspiciousMultipartForm(SuspiciousOperation):
+    """Suspect MIME request in multipart form data"""
+    pass
+
+
+class SuspiciousFileOperation(SuspiciousOperation):
+    """A Suspicious filesystem operation was attempted"""
+    pass
+
+
+class DisallowedHost(SuspiciousOperation):
+    """HTTP_HOST header contains invalid value"""
+    pass
+
+
+class DisallowedRedirect(SuspiciousOperation):
+    """Redirect to scheme not in allowed list"""
     pass
 
 
 class PermissionDenied(Exception):
-    "The user did not have permission to do that"
+    """The user did not have permission to do that"""
     pass
 
 
 class ViewDoesNotExist(Exception):
-    "The requested view does not exist"
+    """The requested view does not exist"""
     pass
 
 
 class MiddlewareNotUsed(Exception):
-    "This middleware is not used in this server configuration"
+    """This middleware is not used in this server configuration"""
     pass
 
 
 class ImproperlyConfigured(Exception):
-    "Django is somehow improperly configured"
+    """Django is somehow improperly configured"""
     pass
 
 
diff --git a/django/core/files/storage.py b/django/core/files/storage.py
index 18d15e1ab6..977b6a68a8 100644
--- a/django/core/files/storage.py
+++ b/django/core/files/storage.py
@@ -8,7 +8,7 @@ import itertools
 from datetime import datetime
 
 from django.conf import settings
-from django.core.exceptions import SuspiciousOperation
+from django.core.exceptions import SuspiciousFileOperation
 from django.core.files import locks, File
 from django.core.files.move import file_move_safe
 from django.utils.encoding import force_text, filepath_to_uri
@@ -260,7 +260,7 @@ class FileSystemStorage(Storage):
         try:
             path = safe_join(self.location, name)
         except ValueError:
-            raise SuspiciousOperation("Attempted access to '%s' denied." % name)
+            raise SuspiciousFileOperation("Attempted access to '%s' denied." % name)
         return os.path.normpath(path)
 
     def size(self, name):
diff --git a/django/core/handlers/base.py b/django/core/handlers/base.py
index 555fd98fc6..59118656c6 100644
--- a/django/core/handlers/base.py
+++ b/django/core/handlers/base.py
@@ -8,7 +8,7 @@ from django import http
 from django.conf import settings
 from django.core import urlresolvers
 from django.core import signals
-from django.core.exceptions import MiddlewareNotUsed, PermissionDenied
+from django.core.exceptions import MiddlewareNotUsed, PermissionDenied, SuspiciousOperation
 from django.db import connections, transaction
 from django.utils.encoding import force_text
 from django.utils.module_loading import import_by_path
@@ -170,11 +170,27 @@ class BaseHandler(object):
                 response = self.handle_uncaught_exception(request,
                         resolver, sys.exc_info())
 
+        except SuspiciousOperation as e:
+            # The request logger receives events for any problematic request
+            # The security logger receives events for all SuspiciousOperations
+            security_logger = logging.getLogger('django.security.%s' %
+                            e.__class__.__name__)
+            security_logger.error(force_text(e))
+
+            try:
+                callback, param_dict = resolver.resolve400()
+                response = callback(request, **param_dict)
+            except:
+                signals.got_request_exception.send(
+                        sender=self.__class__, request=request)
+                response = self.handle_uncaught_exception(request,
+                        resolver, sys.exc_info())
+
         except SystemExit:
             # Allow sys.exit() to actually exit. See tickets #1023 and #4701
             raise
 
-        except: # Handle everything else, including SuspiciousOperation, etc.
+        except: # Handle everything else.
             # Get the exception info now, in case another exception is thrown later.
             signals.got_request_exception.send(sender=self.__class__, request=request)
             response = self.handle_uncaught_exception(request, resolver, sys.exc_info())
diff --git a/django/core/urlresolvers.py b/django/core/urlresolvers.py
index c3d93bb247..5f314ff490 100644
--- a/django/core/urlresolvers.py
+++ b/django/core/urlresolvers.py
@@ -360,6 +360,9 @@ class RegexURLResolver(LocaleRegexProvider):
             callback = getattr(urls, 'handler%s' % view_type)
         return get_callable(callback), {}
 
+    def resolve400(self):
+        return self._resolve_special('400')
+
     def resolve403(self):
         return self._resolve_special('403')
 
diff --git a/django/http/multipartparser.py b/django/http/multipartparser.py
index 26e10da1a2..eeb435fa57 100644
--- a/django/http/multipartparser.py
+++ b/django/http/multipartparser.py
@@ -11,7 +11,7 @@ import cgi
 import sys
 
 from django.conf import settings
-from django.core.exceptions import SuspiciousOperation
+from django.core.exceptions import SuspiciousMultipartForm
 from django.utils.datastructures import MultiValueDict
 from django.utils.encoding import force_text
 from django.utils import six
@@ -370,7 +370,7 @@ class LazyStream(six.Iterator):
                             if current_number == num_bytes])
 
         if number_equal > 40:
-            raise SuspiciousOperation(
+            raise SuspiciousMultipartForm(
                 "The multipart parser got stuck, which shouldn't happen with"
                 " normal uploaded files. Check for malicious upload activity;"
                 " if there is none, report this to the Django developers."
diff --git a/django/http/request.py b/django/http/request.py
index 749b9f2561..e6811aa6cc 100644
--- a/django/http/request.py
+++ b/django/http/request.py
@@ -14,7 +14,7 @@ except ImportError:
 
 from django.conf import settings
 from django.core import signing
-from django.core.exceptions import SuspiciousOperation, ImproperlyConfigured
+from django.core.exceptions import DisallowedHost, ImproperlyConfigured
 from django.core.files import uploadhandler
 from django.http.multipartparser import MultiPartParser
 from django.utils import six
@@ -72,7 +72,7 @@ class HttpRequest(object):
             msg = "Invalid HTTP_HOST header: %r." % host
             if domain:
                 msg += "You may need to add %r to ALLOWED_HOSTS." % domain
-            raise SuspiciousOperation(msg)
+            raise DisallowedHost(msg)
 
     def get_full_path(self):
         # RFC 3986 requires query string arguments to be in the ASCII range.
diff --git a/django/http/response.py b/django/http/response.py
index 671fb1c573..9aa49b1d5f 100644
--- a/django/http/response.py
+++ b/django/http/response.py
@@ -12,7 +12,7 @@ except ImportError:
 from django.conf import settings
 from django.core import signals
 from django.core import signing
-from django.core.exceptions import SuspiciousOperation
+from django.core.exceptions import DisallowedRedirect
 from django.http.cookie import SimpleCookie
 from django.utils import six, timezone
 from django.utils.encoding import force_bytes, iri_to_uri
@@ -452,7 +452,7 @@ class HttpResponseRedirectBase(HttpResponse):
     def __init__(self, redirect_to, *args, **kwargs):
         parsed = urlparse(redirect_to)
         if parsed.scheme and parsed.scheme not in self.allowed_schemes:
-            raise SuspiciousOperation("Unsafe redirect to URL with protocol '%s'" % parsed.scheme)
+            raise DisallowedRedirect("Unsafe redirect to URL with protocol '%s'" % parsed.scheme)
         super(HttpResponseRedirectBase, self).__init__(*args, **kwargs)
         self['Location'] = iri_to_uri(redirect_to)
 
diff --git a/django/test/utils.py b/django/test/utils.py
index fb9221d25c..d178c9b29c 100644
--- a/django/test/utils.py
+++ b/django/test/utils.py
@@ -1,3 +1,5 @@
+from contextlib import contextmanager
+import logging
 import re
 import sys
 import warnings
@@ -401,3 +403,21 @@ class IgnoreDeprecationWarningsMixin(object):
 class IgnorePendingDeprecationWarningsMixin(IgnoreDeprecationWarningsMixin):
 
         warning_class = PendingDeprecationWarning
+
+
+@contextmanager
+def patch_logger(logger_name, log_level):
+    """
+    Context manager that takes a named logger and the logging level
+    and provides a simple mock-like list of messages received
+    """
+    calls = []
+    def replacement(msg):
+        calls.append(msg)
+    logger = logging.getLogger(logger_name)
+    orig = getattr(logger, log_level)
+    setattr(logger, log_level, replacement)
+    try:
+        yield calls
+    finally:
+        setattr(logger, log_level, orig)
diff --git a/django/utils/log.py b/django/utils/log.py
index a9b62caae1..2abf7701cb 100644
--- a/django/utils/log.py
+++ b/django/utils/log.py
@@ -63,6 +63,11 @@ DEFAULT_LOGGING = {
             'level': 'ERROR',
             'propagate': False,
         },
+        'django.security': {
+            'handlers': ['mail_admins'],
+            'level': 'ERROR',
+            'propagate': False,
+        },
         'py.warnings': {
             'handlers': ['console'],
         },
diff --git a/django/views/defaults.py b/django/views/defaults.py
index 89228c50c9..c8a62fc753 100644
--- a/django/views/defaults.py
+++ b/django/views/defaults.py
@@ -43,6 +43,21 @@ def server_error(request, template_name='500.html'):
     return http.HttpResponseServerError(template.render(Context({})))
 
 
+@requires_csrf_token
+def bad_request(request, template_name='400.html'):
+    """
+    400 error handler.
+
+    Templates: :template:`400.html`
+    Context: None
+    """
+    try:
+        template = loader.get_template(template_name)
+    except TemplateDoesNotExist:
+        return http.HttpResponseBadRequest('<h1>Bad Request (400)</h1>')
+    return http.HttpResponseBadRequest(template.render(Context({})))
+
+
 # This can be called when CsrfViewMiddleware.process_view has not run,
 # therefore need @requires_csrf_token in case the template needs
 # {% csrf_token %}.
diff --git a/docs/ref/exceptions.txt b/docs/ref/exceptions.txt
index f9a1715180..6a5e6f49d5 100644
--- a/docs/ref/exceptions.txt
+++ b/docs/ref/exceptions.txt
@@ -44,9 +44,24 @@ SuspiciousOperation
 -------------------
 .. exception:: SuspiciousOperation
 
-    The :exc:`SuspiciousOperation` exception is raised when a user has performed
-    an operation that should be considered suspicious from a security perspective,
-    such as tampering with a session cookie.
+    The :exc:`SuspiciousOperation` exception is raised when a user has
+    performed an operation that should be considered suspicious from a security
+    perspective, such as tampering with a session cookie. Subclasses of
+    SuspiciousOperation include:
+
+    * DisallowedHost
+    * DisallowedModelAdminLookup
+    * DisallowedRedirect
+    * InvalidSessionKey
+    * SuspiciousFileOperation
+    * SuspiciousMultipartForm
+    * SuspiciousSession
+    * WizardViewCookieModified
+
+    If a ``SuspiciousOperation`` exception reaches the WSGI handler level it is
+    logged at the ``Error`` level and results in
+    a :class:`~django.http.HttpResponseBadRequest`. See the :doc:`logging
+    documentation </topics/logging/>` for more information.
 
 PermissionDenied
 ----------------
diff --git a/docs/releases/1.6.txt b/docs/releases/1.6.txt
index 35488b4110..825c5dc28d 100644
--- a/docs/releases/1.6.txt
+++ b/docs/releases/1.6.txt
@@ -270,6 +270,13 @@ Minor features
   stores active language in session if it is not present there. This
   prevents loss of language settings after session flush, e.g. logout.
 
+* :exc:`~django.core.exceptions.SuspiciousOperation` has been differentiated
+  into a number of subclasses, and each will log to a matching named logger
+  under the ``django.security`` logging hierarchy. Along with this change,
+  a ``handler400`` mechanism and default view are used whenever
+  a ``SuspiciousOperation`` reaches the WSGI handler to return an
+  ``HttpResponseBadRequest``.
+
 Backwards incompatible changes in 1.6
 =====================================
 
diff --git a/docs/topics/http/views.txt b/docs/topics/http/views.txt
index 2ccedec2f7..5c27c9c958 100644
--- a/docs/topics/http/views.txt
+++ b/docs/topics/http/views.txt
@@ -231,3 +231,25 @@ same way you can for the 404 and 500 views by specifying a ``handler403`` in
 your URLconf::
 
     handler403 = 'mysite.views.my_custom_permission_denied_view'
+
+.. _http_bad_request_view:
+
+The 400 (bad request) view
+--------------------------
+
+When a :exc:`~django.core.exceptions.SuspiciousOperation` is raised in Django,
+the it may be handled by a component of Django (for example resetting the
+session data). If not specifically handled, Django will consider the current
+request a 'bad request' instead of a server error.
+
+The view ``django.views.defaults.bad_request``, is otherwise very similar to
+the ``server_error`` view, but returns with the status code 400 indicating that
+the error condition was the result of a client operation.
+
+Like the ``server_error`` view, the default ``bad_request`` should suffice for
+99% of Web applications, but if you want to override the view, you can specify
+``handler400`` in your URLconf, like so::
+
+    handler400 = 'mysite.views.my_custom_bad_request_view'
+
+``bad_request`` views are also only used when :setting:`DEBUG` is ``False``.
diff --git a/docs/topics/logging.txt b/docs/topics/logging.txt
index a31dc01cc5..a88201ad47 100644
--- a/docs/topics/logging.txt
+++ b/docs/topics/logging.txt
@@ -394,7 +394,7 @@ requirements of logging in Web server environment.
 Loggers
 -------
 
-Django provides three built-in loggers.
+Django provides four built-in loggers.
 
 ``django``
 ~~~~~~~~~~
@@ -434,6 +434,35 @@ For performance reasons, SQL logging is only enabled when
 ``settings.DEBUG`` is set to ``True``, regardless of the logging
 level or handlers that are installed.
 
+``django.security.*``
+~~~~~~~~~~~~~~~~~~~~~~
+
+The security loggers will receive messages on any occurrence of
+:exc:`~django.core.exceptions.SuspiciousOperation`. There is a sub-logger for
+each sub-type of SuspiciousOperation. The level of the log event depends on
+where the exception is handled.  Most occurrences are logged as a warning, while
+any ``SuspiciousOperation`` that reaches the WSGI handler will be logged as an
+error. For example, when an HTTP ``Host`` header is included in a request from
+a client that does not match :setting:`ALLOWED_HOSTS`, Django will return a 400
+response, and an error message will be logged to the
+``django.security.DisallowedHost`` logger.
+
+Only the parent ``django.security`` logger is configured by default, and all
+child loggers will propagate to the parent logger. The ``django.security``
+logger is configured the same as the ``django.request`` logger, and any error
+events will be mailed to admins. Requests resulting in a 400 response due to
+a ``SuspiciousOperation`` will not be logged to the ``django.request`` logger,
+but only to the ``django.security`` logger.
+
+To silence a particular type of SuspiciousOperation, you can override that
+specific logger following this example::
+
+        'loggers': {
+            'django.security.DisallowedHost': {
+                'handlers': ['null'],
+                'propagate': False,
+            },
+
 Handlers
 --------
 
diff --git a/tests/admin_views/tests.py b/tests/admin_views/tests.py
index c0f6533cb2..3485ea353b 100644
--- a/tests/admin_views/tests.py
+++ b/tests/admin_views/tests.py
@@ -11,7 +11,6 @@ except ImportError:  # Python 2
 
 from django.conf import settings, global_settings
 from django.core import mail
-from django.core.exceptions import SuspiciousOperation
 from django.core.files import temp as tempfile
 from django.core.urlresolvers import reverse
 # Register auth models with the admin.
@@ -30,6 +29,7 @@ from django.db import connection
 from django.forms.util import ErrorList
 from django.template.response import TemplateResponse
 from django.test import TestCase
+from django.test.utils import patch_logger
 from django.utils import formats, translation, unittest
 from django.utils.cache import get_max_age
 from django.utils.encoding import iri_to_uri, force_bytes
@@ -543,20 +543,21 @@ class AdminViewBasicTest(TestCase):
                 self.assertContains(response, '%Y-%m-%d %H:%M:%S')
 
     def test_disallowed_filtering(self):
-        self.assertRaises(SuspiciousOperation,
-            self.client.get, "/test_admin/admin/admin_views/album/?owner__email__startswith=fuzzy"
-        )
+        with patch_logger('django.security.DisallowedModelAdminLookup', 'error') as calls:
+            response = self.client.get("/test_admin/admin/admin_views/album/?owner__email__startswith=fuzzy")
+            self.assertEqual(response.status_code, 400)
+            self.assertEqual(len(calls), 1)
 
-        try:
-            self.client.get("/test_admin/admin/admin_views/thing/?color__value__startswith=red")
-            self.client.get("/test_admin/admin/admin_views/thing/?color__value=red")
-        except SuspiciousOperation:
-            self.fail("Filters are allowed if explicitly included in list_filter")
+        # Filters are allowed if explicitly included in list_filter
+        response = self.client.get("/test_admin/admin/admin_views/thing/?color__value__startswith=red")
+        self.assertEqual(response.status_code, 200)
+        response = self.client.get("/test_admin/admin/admin_views/thing/?color__value=red")
+        self.assertEqual(response.status_code, 200)
 
-        try:
-            self.client.get("/test_admin/admin/admin_views/person/?age__gt=30")
-        except SuspiciousOperation:
-            self.fail("Filters should be allowed if they involve a local field without the need to whitelist them in list_filter or date_hierarchy.")
+        # Filters should be allowed if they involve a local field without the
+        # need to whitelist them in list_filter or date_hierarchy.
+        response = self.client.get("/test_admin/admin/admin_views/person/?age__gt=30")
+        self.assertEqual(response.status_code, 200)
 
         e1 = Employee.objects.create(name='Anonymous', gender=1, age=22, alive=True, code='123')
         e2 = Employee.objects.create(name='Visitor', gender=2, age=19, alive=True, code='124')
@@ -574,10 +575,9 @@ class AdminViewBasicTest(TestCase):
         ForeignKey 'limit_choices_to' should be allowed, otherwise raw_id_fields
         can break.
         """
-        try:
-            self.client.get("/test_admin/admin/admin_views/inquisition/?leader__name=Palin&leader__age=27")
-        except SuspiciousOperation:
-            self.fail("Filters should be allowed if they are defined on a ForeignKey pointing to this model")
+        # Filters should be allowed if they are defined on a ForeignKey pointing to this model
+        response = self.client.get("/test_admin/admin/admin_views/inquisition/?leader__name=Palin&leader__age=27")
+        self.assertEqual(response.status_code, 200)
 
     def test_hide_change_password(self):
         """
diff --git a/tests/handlers/tests.py b/tests/handlers/tests.py
index 3680eecdd2..397b63647a 100644
--- a/tests/handlers/tests.py
+++ b/tests/handlers/tests.py
@@ -61,6 +61,7 @@ class TransactionsPerRequestTests(TransactionTestCase):
             connection.settings_dict['ATOMIC_REQUESTS'] = old_atomic_requests
         self.assertContains(response, 'False')
 
+
 class SignalsTests(TestCase):
     urls = 'handlers.urls'
 
@@ -89,3 +90,11 @@ class SignalsTests(TestCase):
         self.assertEqual(self.signals, ['started'])
         self.assertEqual(b''.join(response.streaming_content), b"streaming content")
         self.assertEqual(self.signals, ['started', 'finished'])
+
+
+class HandlerSuspiciousOpsTest(TestCase):
+    urls = 'handlers.urls'
+
+    def test_suspiciousop_in_view_returns_400(self):
+        response = self.client.get('/suspicious/')
+        self.assertEqual(response.status_code, 400)
diff --git a/tests/handlers/urls.py b/tests/handlers/urls.py
index 29858055ab..eaf764b00b 100644
--- a/tests/handlers/urls.py
+++ b/tests/handlers/urls.py
@@ -9,4 +9,5 @@ urlpatterns = patterns('',
     url(r'^streaming/$', views.streaming),
     url(r'^in_transaction/$', views.in_transaction),
     url(r'^not_in_transaction/$', views.not_in_transaction),
+    url(r'^suspicious/$', views.suspicious),
 )
diff --git a/tests/handlers/views.py b/tests/handlers/views.py
index 9cc86ae6f3..1b75b27043 100644
--- a/tests/handlers/views.py
+++ b/tests/handlers/views.py
@@ -1,5 +1,6 @@
 from __future__ import unicode_literals
 
+from django.core.exceptions import SuspiciousOperation
 from django.db import connection, transaction
 from django.http import HttpResponse, StreamingHttpResponse
 
@@ -15,3 +16,6 @@ def in_transaction(request):
 @transaction.non_atomic_requests
 def not_in_transaction(request):
     return HttpResponse(str(connection.in_atomic_block))
+
+def suspicious(request):
+    raise SuspiciousOperation('dubious')
diff --git a/tests/logging_tests/tests.py b/tests/logging_tests/tests.py
index 8e5445cd42..0c2d269464 100644
--- a/tests/logging_tests/tests.py
+++ b/tests/logging_tests/tests.py
@@ -8,9 +8,10 @@ import warnings
 from django.conf import LazySettings
 from django.core import mail
 from django.test import TestCase, RequestFactory
-from django.test.utils import override_settings
+from django.test.utils import override_settings, patch_logger
 from django.utils.encoding import force_text
-from django.utils.log import CallbackFilter, RequireDebugFalse, RequireDebugTrue
+from django.utils.log import (CallbackFilter, RequireDebugFalse,
+    RequireDebugTrue)
 from django.utils.six import StringIO
 from django.utils.unittest import skipUnless
 
@@ -354,3 +355,22 @@ class SettingsConfigureLogging(TestCase):
         settings.configure(
             LOGGING_CONFIG='logging_tests.tests.dictConfig')
         self.assertTrue(dictConfig.called)
+
+
+class SecurityLoggerTest(TestCase):
+
+    urls = 'logging_tests.urls'
+
+    def test_suspicious_operation_creates_log_message(self):
+        with self.settings(DEBUG=True):
+            with patch_logger('django.security.SuspiciousOperation', 'error') as calls:
+                response = self.client.get('/suspicious/')
+                self.assertEqual(len(calls), 1)
+                self.assertEqual(calls[0], 'dubious')
+
+    def test_suspicious_operation_uses_sublogger(self):
+        with self.settings(DEBUG=True):
+            with patch_logger('django.security.DisallowedHost', 'error') as calls:
+                response = self.client.get('/suspicious_spec/')
+                self.assertEqual(len(calls), 1)
+                self.assertEqual(calls[0], 'dubious')
diff --git a/tests/logging_tests/urls.py b/tests/logging_tests/urls.py
new file mode 100644
index 0000000000..c738bd565c
--- /dev/null
+++ b/tests/logging_tests/urls.py
@@ -0,0 +1,10 @@
+from __future__ import unicode_literals
+
+from django.conf.urls import patterns, url
+
+from . import views
+
+urlpatterns = patterns('',
+    url(r'^suspicious/$', views.suspicious),
+    url(r'^suspicious_spec/$', views.suspicious_spec),
+)
diff --git a/tests/logging_tests/views.py b/tests/logging_tests/views.py
new file mode 100644
index 0000000000..c685bcc005
--- /dev/null
+++ b/tests/logging_tests/views.py
@@ -0,0 +1,11 @@
+from __future__ import unicode_literals
+
+from django.core.exceptions import SuspiciousOperation, DisallowedHost
+
+
+def suspicious(request):
+    raise SuspiciousOperation('dubious')
+
+
+def suspicious_spec(request):
+    raise DisallowedHost('dubious')
diff --git a/tests/test_client_regress/tests.py b/tests/test_client_regress/tests.py
index 2582b210c4..6a58ef6344 100644
--- a/tests/test_client_regress/tests.py
+++ b/tests/test_client_regress/tests.py
@@ -7,7 +7,6 @@ from __future__ import unicode_literals
 import os
 
 from django.conf import settings
-from django.core.exceptions import SuspiciousOperation
 from django.core.urlresolvers import reverse
 from django.template import (TemplateDoesNotExist, TemplateSyntaxError,
     Context, Template, loader)
@@ -20,6 +19,7 @@ from django.utils._os import upath
 from django.utils.translation import ugettext_lazy
 from django.http import HttpResponse
 
+from .views import CustomTestException
 
 @override_settings(
     TEMPLATE_DIRS=(os.path.join(os.path.dirname(upath(__file__)), 'templates'),)
@@ -619,7 +619,7 @@ class ExceptionTests(TestCase):
         try:
             response = self.client.get("/test_client_regress/staff_only/")
             self.fail("General users should not be able to visit this page")
-        except SuspiciousOperation:
+        except CustomTestException:
             pass
 
         # At this point, an exception has been raised, and should be cleared.
@@ -629,7 +629,7 @@ class ExceptionTests(TestCase):
         self.assertTrue(login, 'Could not log in')
         try:
             self.client.get("/test_client_regress/staff_only/")
-        except SuspiciousOperation:
+        except CustomTestException:
             self.fail("Staff should be able to visit this page")
 
 
diff --git a/tests/test_client_regress/views.py b/tests/test_client_regress/views.py
index 7e86ffd8ca..71e5b526e5 100644
--- a/tests/test_client_regress/views.py
+++ b/tests/test_client_regress/views.py
@@ -3,12 +3,15 @@ import json
 from django.conf import settings
 from django.contrib.auth.decorators import login_required
 from django.http import HttpResponse, HttpResponseRedirect
-from django.core.exceptions import SuspiciousOperation
 from django.shortcuts import render_to_response
 from django.core.serializers.json import DjangoJSONEncoder
 from django.test.client import CONTENT_TYPE_RE
 from django.template import RequestContext
 
+
+class CustomTestException(Exception):
+    pass
+
 def no_template_view(request):
     "A simple view that expects a GET request, and returns a rendered template"
     return HttpResponse("No template used. Sample content: twice once twice. Content ends.")
@@ -18,7 +21,7 @@ def staff_only_view(request):
     if request.user.is_staff:
         return HttpResponse('')
     else:
-        raise SuspiciousOperation()
+        raise CustomTestException()
 
 def get_view(request):
     "A simple login protected view"
diff --git a/tests/urlpatterns_reverse/tests.py b/tests/urlpatterns_reverse/tests.py
index d5d9b3a709..f54c796d30 100644
--- a/tests/urlpatterns_reverse/tests.py
+++ b/tests/urlpatterns_reverse/tests.py
@@ -516,7 +516,7 @@ class RequestURLconfTests(TestCase):
             b''.join(self.client.get('/second_test/'))
 
 class ErrorHandlerResolutionTests(TestCase):
-    """Tests for handler404 and handler500"""
+    """Tests for handler400, handler404 and handler500"""
 
     def setUp(self):
         from django.core.urlresolvers import RegexURLResolver
@@ -528,12 +528,14 @@ class ErrorHandlerResolutionTests(TestCase):
     def test_named_handlers(self):
         from .views import empty_view
         handler = (empty_view, {})
+        self.assertEqual(self.resolver.resolve400(), handler)
         self.assertEqual(self.resolver.resolve404(), handler)
         self.assertEqual(self.resolver.resolve500(), handler)
 
     def test_callable_handers(self):
         from .views import empty_view
         handler = (empty_view, {})
+        self.assertEqual(self.callable_resolver.resolve400(), handler)
         self.assertEqual(self.callable_resolver.resolve404(), handler)
         self.assertEqual(self.callable_resolver.resolve500(), handler)
 
diff --git a/tests/urlpatterns_reverse/urls_error_handlers.py b/tests/urlpatterns_reverse/urls_error_handlers.py
index be4f42afbc..7146fdf43c 100644
--- a/tests/urlpatterns_reverse/urls_error_handlers.py
+++ b/tests/urlpatterns_reverse/urls_error_handlers.py
@@ -4,5 +4,6 @@ from django.conf.urls import patterns
 
 urlpatterns = patterns('')
 
+handler400 = 'urlpatterns_reverse.views.empty_view'
 handler404 = 'urlpatterns_reverse.views.empty_view'
 handler500 = 'urlpatterns_reverse.views.empty_view'
diff --git a/tests/urlpatterns_reverse/urls_error_handlers_callables.py b/tests/urlpatterns_reverse/urls_error_handlers_callables.py
index fe2d3137e9..befeccaf45 100644
--- a/tests/urlpatterns_reverse/urls_error_handlers_callables.py
+++ b/tests/urlpatterns_reverse/urls_error_handlers_callables.py
@@ -9,5 +9,6 @@ from .views import empty_view
 
 urlpatterns = patterns('')
 
+handler400 = empty_view
 handler404 = empty_view
 handler500 = empty_view