diff --git a/src/Dev/Validation/DatabaseAdminExtension.php b/src/Dev/Validation/DatabaseAdminExtension.php
index fbcf5ffc244..db0c83351d8 100644
--- a/src/Dev/Validation/DatabaseAdminExtension.php
+++ b/src/Dev/Validation/DatabaseAdminExtension.php
@@ -21,7 +21,7 @@ class DatabaseAdminExtension extends Extension
      * @param bool $testMode
      * @throws ReflectionException
      */
-    public function onAfterBuild(bool $quiet, bool $populate, bool $testMode): void
+    protected function onAfterBuild(bool $quiet, bool $populate, bool $testMode): void
     {
         $service = RelationValidationService::singleton();
 
diff --git a/src/ORM/DataExtension.php b/src/ORM/DataExtension.php
index 399182d3f17..53ffad3b71c 100644
--- a/src/ORM/DataExtension.php
+++ b/src/ORM/DataExtension.php
@@ -38,7 +38,7 @@ public function __construct()
      * @param ValidationResult $validationResult Local validation result
      * @throws ValidationException
      */
-    public function validate(ValidationResult $validationResult)
+    protected function updateValidate(ValidationResult $validationResult)
     {
     }
 
@@ -112,7 +112,7 @@ protected function onAfterDelete()
      *
      * See {@link DataObject::requireDefaultRecords()} for context.
      */
-    public function requireDefaultRecords()
+    protected function onRequireDefaultRecords()
     {
     }
 
@@ -121,7 +121,7 @@ public function requireDefaultRecords()
      *
      * See {@link DataObject::populateDefaults()} for context.
      */
-    public function populateDefaults()
+    protected function onAfterPopulateDefaults()
     {
     }
 
@@ -130,7 +130,7 @@ public function populateDefaults()
      *
      * See {@link DataObject::onAfterBuild()} for context.
      */
-    public function onAfterBuild()
+    protected function onAfterBuild()
     {
     }
 
@@ -144,7 +144,7 @@ public function onAfterBuild()
      * @param Member $member
      * @return bool|null
      */
-    public function can($member)
+    protected function can($member)
     {
     }
 
@@ -158,7 +158,7 @@ public function can($member)
      * @param Member $member
      * @return bool|null
      */
-    public function canEdit($member)
+    protected function canEdit($member)
     {
     }
 
@@ -172,7 +172,7 @@ public function canEdit($member)
      * @param Member $member
      * @return bool|null
      */
-    public function canDelete($member)
+    protected function canDelete($member)
     {
     }
 
@@ -186,7 +186,7 @@ public function canDelete($member)
      * @param Member $member
      * @return bool|null
      */
-    public function canCreate($member)
+    protected function canCreate($member)
     {
     }
 
diff --git a/src/ORM/DataObject.php b/src/ORM/DataObject.php
index 43414fc301a..36bce9e59d6 100644
--- a/src/ORM/DataObject.php
+++ b/src/ORM/DataObject.php
@@ -1228,7 +1228,7 @@ public function forceChange()
     public function validate()
     {
         $result = ValidationResult::create();
-        $this->extend('validate', $result);
+        $this->extend('updateValidate', $result);
         return $result;
     }
 
@@ -1311,7 +1311,6 @@ protected function onAfterDelete()
      * Will traverse the defaults of the current class and all its parent classes.
      * Called by the constructor when creating new records.
      *
-     * @uses DataExtension::populateDefaults()
      * @return static $this
      */
     public function populateDefaults()
@@ -1348,7 +1347,7 @@ public function populateDefaults()
             }
         }
 
-        $this->extend('populateDefaults');
+        $this->extend('onAfterPopulateDefaults');
         return $this;
     }
 
@@ -3542,7 +3541,7 @@ public function flushCache($persistent = true)
             }
         }
 
-        $this->extend('flushCache');
+        $this->extend('onFlushCache');
 
         $this->components = [];
         $this->eagerLoadedData = [];
@@ -3800,7 +3799,7 @@ public function requireDefaultRecords()
         }
 
         // Let any extensions make their own database default data
-        $this->extend('requireDefaultRecords', $dummy);
+        $this->extend('onRequireDefaultRecords', $dummy);
     }
 
     /**
diff --git a/src/ORM/Hierarchy/Hierarchy.php b/src/ORM/Hierarchy/Hierarchy.php
index 40adbb8bf2e..ef4ab01dc11 100644
--- a/src/ORM/Hierarchy/Hierarchy.php
+++ b/src/ORM/Hierarchy/Hierarchy.php
@@ -116,7 +116,7 @@ public static function get_extra_config($class, $extension, $args)
      *
      * @param ValidationResult $validationResult
      */
-    public function validate(ValidationResult $validationResult)
+    protected function updateValidate(ValidationResult $validationResult)
     {
         // The object is new, won't be looping.
         $owner = $this->owner;
@@ -572,7 +572,7 @@ public function getBreadcrumbs($separator = ' » ')
      * - Children (instance)
      * - NumChildren (instance)
      */
-    public function flushCache()
+    protected function onFlushCache()
     {
         $this->owner->_cache_children = null;
         Hierarchy::$cache_numChildren = [];
diff --git a/src/Security/InheritedPermissionFlusher.php b/src/Security/InheritedPermissionFlusher.php
index d4aa344e4a4..b815b8859ec 100644
--- a/src/Security/InheritedPermissionFlusher.php
+++ b/src/Security/InheritedPermissionFlusher.php
@@ -23,7 +23,7 @@ class InheritedPermissionFlusher extends DataExtension implements Flushable
      */
     public static function flush()
     {
-        singleton(__CLASS__)->flushCache();
+        singleton(__CLASS__)->onFlushCache();
     }
 
     /**
@@ -77,7 +77,7 @@ public function getServices()
     /**
      * Flushes all registered MemberCacheFlusher services
      */
-    public function flushCache()
+    protected function onFlushCache()
     {
         $ids = $this->getMemberIDList();
         foreach ($this->getServices() as $service) {
diff --git a/src/Security/Member.php b/src/Security/Member.php
index ad241beac8e..82b228d8ef4 100644
--- a/src/Security/Member.php
+++ b/src/Security/Member.php
@@ -452,7 +452,7 @@ public function isPasswordExpired(): bool
      */
     public function beforeMemberLoggedIn()
     {
-        $this->extend('beforeMemberLoggedIn');
+        $this->extend('onBeforeMemberLoggedIn');
     }
 
     /**
@@ -470,7 +470,7 @@ public function afterMemberLoggedIn()
         $this->write();
 
         // Audit logging hook
-        $this->extend('afterMemberLoggedIn');
+        $this->extend('onAfterMemberLoggedIn');
     }
 
     /**
@@ -497,7 +497,7 @@ public function regenerateTempID()
      */
     public function beforeMemberLoggedOut(HTTPRequest $request = null)
     {
-        $this->extend('beforeMemberLoggedOut', $request);
+        $this->extend('onBeforeMemberLoggedOut', $request);
     }
 
     /**
@@ -507,7 +507,7 @@ public function beforeMemberLoggedOut(HTTPRequest $request = null)
      */
     public function afterMemberLoggedOut(HTTPRequest $request = null)
     {
-        $this->extend('afterMemberLoggedOut', $request);
+        $this->extend('onAfterMemberLoggedOut', $request);
     }
 
     /**
@@ -1709,7 +1709,7 @@ public function registerFailedLogin()
                 $this->FailedLoginCount = 0;
             }
         }
-        $this->extend('registerFailedLogin');
+        $this->extend('onRegisterFailedLogin');
         $this->write();
     }
 
diff --git a/src/Security/MemberAuthenticator/LostPasswordHandler.php b/src/Security/MemberAuthenticator/LostPasswordHandler.php
index 41d3718b210..0e019552e0d 100644
--- a/src/Security/MemberAuthenticator/LostPasswordHandler.php
+++ b/src/Security/MemberAuthenticator/LostPasswordHandler.php
@@ -152,7 +152,7 @@ public function redirectToLostPassword()
     /**
      * Forgot password form handler method.
      * Called when the user clicks on "I've lost my password".
-     * Extensions can use the 'forgotPassword' method to veto executing
+     * Extensions can use the 'onForgotPassword' method to veto executing
      * the logic, by returning FALSE. In this case, the user will be redirected back
      * to the form without further action. It is recommended to set a message
      * in the form detailing why the action was denied.
@@ -168,7 +168,7 @@ public function forgotPassword(array $data, Form $form): HTTPResponse
         $member = $this->getMemberFromData($data);
 
         // Allow vetoing forgot password requests
-        $results = $this->extend('forgotPassword', $member);
+        $results = $this->extend('onForgotPassword', $member);
         if ($results && is_array($results) && in_array(false, $results ?? [], true)) {
             return $this->redirectToLostPassword();
         }
diff --git a/src/Security/MemberAuthenticator/MemberAuthenticator.php b/src/Security/MemberAuthenticator/MemberAuthenticator.php
index 29ed27a17e8..ec53cffebd5 100644
--- a/src/Security/MemberAuthenticator/MemberAuthenticator.php
+++ b/src/Security/MemberAuthenticator/MemberAuthenticator.php
@@ -195,18 +195,18 @@ protected function recordLoginAttempt($data, HTTPRequest $request, $member, $suc
             $attempt->Status = LoginAttempt::SUCCESS;
 
             // Audit logging hook
-            $member->extend('authenticationSucceeded');
+            $member->extend('onAuthenticationSucceeded');
         } else {
             // Failed login - we're trying to see if a user exists with this email (disregarding wrong passwords)
             $attempt->Status = LoginAttempt::FAILURE;
             if ($member) {
                 // Audit logging hook
                 $attempt->MemberID = $member->ID;
-                $member->extend('authenticationFailed', $data, $request);
+                $member->extend('onAuthenticationFailed', $data, $request);
             } else {
                 // Audit logging hook
                 Member::singleton()
-                   ->extend('authenticationFailedUnknownUser', $data, $request);
+                   ->extend('onAuthenticationFailedUnknownUser', $data, $request);
             }
         }
 
diff --git a/src/Security/MemberAuthenticator/MemberLoginForm.php b/src/Security/MemberAuthenticator/MemberLoginForm.php
index eba6afc74dd..8ce5c2b4b99 100644
--- a/src/Security/MemberAuthenticator/MemberLoginForm.php
+++ b/src/Security/MemberAuthenticator/MemberLoginForm.php
@@ -23,9 +23,9 @@
  * Log-in form for the "member" authentication method.
  *
  * Available extension points:
- * - "authenticationFailed": Called when login was not successful.
+ * - "onAuthenticationFailed": Called when login was not successful.
  *    Arguments: $data containing the form submission
- * - "forgotPassword": Called before forgot password logic kicks in,
+ * - "onForgotPassword": Called before forgot password logic kicks in,
  *    allowing extensions to "veto" execution by returning FALSE.
  *    Arguments: $member containing the detected Member record
  */
diff --git a/tests/php/ORM/DataExtensionTest/Extension1.php b/tests/php/ORM/DataExtensionTest/Extension1.php
index 010e3a863e2..1b9fb62ae20 100644
--- a/tests/php/ORM/DataExtensionTest/Extension1.php
+++ b/tests/php/ORM/DataExtensionTest/Extension1.php
@@ -8,17 +8,17 @@
 class Extension1 extends DataExtension implements TestOnly
 {
 
-    public function canOne($member = null)
+    protected function canOne($member = null)
     {
         return true;
     }
 
-    public function canTwo($member = null)
+    protected function canTwo($member = null)
     {
         return false;
     }
 
-    public function canThree($member = null)
+    protected function canThree($member = null)
     {
     }
 }
diff --git a/tests/php/ORM/DataExtensionTest/Extension2.php b/tests/php/ORM/DataExtensionTest/Extension2.php
index c37e37d13a0..10f964a0f0c 100644
--- a/tests/php/ORM/DataExtensionTest/Extension2.php
+++ b/tests/php/ORM/DataExtensionTest/Extension2.php
@@ -8,17 +8,17 @@
 class Extension2 extends DataExtension implements TestOnly
 {
 
-    public function canOne($member = null)
+    protected function canOne($member = null)
     {
         return true;
     }
 
-    public function canTwo($member = null)
+    protected function canTwo($member = null)
     {
         return true;
     }
 
-    public function canThree($member = null)
+    protected function canThree($member = null)
     {
     }
 }
diff --git a/tests/php/Security/MemberTest/EditingAllowedDeletingDeniedExtension.php b/tests/php/Security/MemberTest/EditingAllowedDeletingDeniedExtension.php
index ac61a60ca15..6afd5185a04 100644
--- a/tests/php/Security/MemberTest/EditingAllowedDeletingDeniedExtension.php
+++ b/tests/php/Security/MemberTest/EditingAllowedDeletingDeniedExtension.php
@@ -8,17 +8,17 @@
 class EditingAllowedDeletingDeniedExtension extends DataExtension implements TestOnly
 {
 
-    public function canView($member = null)
+    protected function canView($member = null)
     {
         return true;
     }
 
-    public function canEdit($member = null)
+    protected function canEdit($member = null)
     {
         return true;
     }
 
-    public function canDelete($member = null)
+    protected function canDelete($member = null)
     {
         return false;
     }
diff --git a/tests/php/Security/MemberTest/ViewingAllowedExtension.php b/tests/php/Security/MemberTest/ViewingAllowedExtension.php
index e941dd472e0..b71ccbfae92 100644
--- a/tests/php/Security/MemberTest/ViewingAllowedExtension.php
+++ b/tests/php/Security/MemberTest/ViewingAllowedExtension.php
@@ -8,7 +8,7 @@
 class ViewingAllowedExtension extends DataExtension implements TestOnly
 {
 
-    public function canView($member = null)
+    protected function canView($member = null)
     {
         return true;
     }
diff --git a/tests/php/Security/MemberTest/ViewingDeniedExtension.php b/tests/php/Security/MemberTest/ViewingDeniedExtension.php
index 82089daaaf4..35ef55db174 100644
--- a/tests/php/Security/MemberTest/ViewingDeniedExtension.php
+++ b/tests/php/Security/MemberTest/ViewingDeniedExtension.php
@@ -8,7 +8,7 @@
 class ViewingDeniedExtension extends DataExtension implements TestOnly
 {
 
-    public function canView($member = null)
+    protected function canView($member = null)
     {
         return false;
     }