Windows NTFS Permissions: Security, Access Control & Troubleshooting
NTFS (New Technology File System) is the default file system for Windows operating systems, providing powerful security features including file-level permissions, encryption, journaling, compression, disk quotas, and much more. Its comprehensive security model allows system administrators to precisely control how users and groups can interact with folders and files through granular NTFS permissions.
Understanding Basic and Advanced NTFS Permissions
Windows NTFS permissions are organized into two levels: six basic permissions (for everyday use) and thirteen advanced permissions (for detailed control). Each basic permission contains a specific combination of advanced permissions, making it easier to apply appropriate security settings to your Windows files and folders.
| ADVANCED PERMISSION | Read | Write | List Folder Contents | Read & Execute | Modify | Full Control |
|---|---|---|---|---|---|---|
| Traverse Folder / Execute File | ||||||
| List Folder / Read Data | ||||||
| Read Attributes | ||||||
| Read Extended Attributes | ||||||
| Create Files / Write Data | ||||||
| Create Folders / Append Data | ||||||
| Write Attributes | ||||||
| Write Extended Attributes | ||||||
| Delete Subfolders and Files | ||||||
| Delete | ||||||
| Read Permissions | ||||||
| Change Permissions | ||||||
| Take Ownership |
NTFS permissions behave differently depending on whether they're applied to folders or files. Below is a detailed explanation of how basic permissions function in each context.
| Basic Permission | Folder Permissions | File Permissions |
|---|---|---|
| Read | Allows viewing and listing of files and subfolders within the directory | Allows viewing or accessing the file's contents |
| Write | Allows creating new files and subfolders within the directory | Allows modifying and writing to a file |
| Read & Execute | Allows viewing and listing files/subfolders and executing files; inherited by both files and folders | Allows viewing file contents and executing/running the file |
| List Folder Contents | Allows viewing and listing files/subfolders and executing files; inherited by folders only | Not applicable to files |
| Modify | Allows reading, writing, and deleting files/subfolders; includes deleting the folder itself | Allows reading, writing, and deleting the file |
| Full Control | Provides complete access: reading, writing, changing permissions, taking ownership, and deleting files/subfolders | Provides complete access: reading, writing, changing permissions, taking ownership, and deleting the file |
How NTFS Advanced Permissions Work: Detailed Explanation
Advanced permissions (also called "special permissions") provide granular control over file system objects. Here's what each one does:
- Traverse Folder / Execute File - For folders: allows navigation through the folder structure even without permissions for intermediate folders. For files: allows running program files.
- List Folder / Read Data - For folders: allows viewing file and subfolder names. For files: allows viewing the file's content.
- Read Attributes - Allows viewing basic file or folder attributes like read-only and hidden status.
- Read Extended Attributes - Allows viewing additional attributes defined by applications.
- Create Files / Write Data - For folders: allows creating new files. For files: allows modifying content and overwriting existing data.
- Create Folders / Append Data - For folders: allows creating new subfolders. For files: allows adding data to the end of files without modifying existing content.
- Write Attributes - Allows modifying file or folder attributes like read-only or hidden status.
- Write Extended Attributes - Allows changing additional attributes defined by applications.
- Delete Subfolders and Files - Allows deleting contents within a folder, even without explicit Delete permission on those items.
- Delete - Allows deleting the specific file or folder. Note: users can still delete objects if they have "Delete Subfolders and Files" permission on the parent folder.
- Read Permissions - Allows viewing the permission settings for files and folders.
- Change Permissions - Allows modifying permission settings for files and folders.
- Take Ownership - Allows becoming the owner of a file or folder. Owners can always change permissions regardless of other security settings.
NTFS Permission Inheritance: How It Works
By default, Windows NTFS uses permission inheritance, where files and folders automatically receive the same permissions as their parent folder. This crucial security feature dramatically simplifies permission management across large file systems. Without inheritance, administrators would need to manually configure permissions on every single object.
In certain scenarios, you may need to create custom permission structures for specific file system branches. This is accomplished by breaking inheritance (disabling permission propagation) for selected objects and then assigning explicit permissions tailored to your security requirements.
Windows Network Share Permissions vs. NTFS Permissions
When sharing folders over a network in Windows environments, share permissions work alongside NTFS permissions to control access. It's important to understand that share permissions are completely separate from NTFS permissions and only apply when accessing resources over the network. Share permissions offer just three access levels (Read, Change, and Full Control), making them significantly less granular than NTFS permissions.
Essential Rules for Windows Permission Evaluation
Understanding how Windows evaluates permissions is critical for troubleshooting access issues. These are the key rules that determine effective permissions:
- Local access rule: When accessing files locally, only NTFS permissions apply.
- Network access rule: When accessing through a network share, both share and NTFS permissions apply, with the most restrictive permission taking precedence.
- Group membership rule: A user's effective permissions combine all their individual permissions plus all permissions from every group they belong to.
- Explicit vs. inherited rule: Explicitly assigned permissions override inherited permissions.
- Inheritance proximity rule: Permissions inherited from a parent folder override permissions inherited from grandparent or higher-level folders.
- Deny precedence rule: Explicit Deny permissions override any Allow permissions, but explicit Allow permissions override inherited Deny permissions.
FAQs About Windows NTFS Permissions
What's the difference between NTFS and share permissions?
NTFS permissions apply to local and network access and offer 6 basic and 13 advanced permission types. Share permissions only apply when accessing resources over a network and offer just 3 permission levels (Read, Change, Full Control). When accessing shared resources remotely, both permission sets apply with the most restrictive taking effect.
How do I fix "Access Denied" errors with NTFS permissions?
To resolve "Access Denied" errors: 1) Check if you're a member of groups with necessary permissions, 2) Look for explicit Deny permissions that may override Allow permissions, 3) Verify inheritance settings haven't been broken, 4) Check if ownership has changed, and 5) For network resources, ensure both share and NTFS permissions allow the required access level.
NTFS Permissions Resources and Tools