Effective permissions

What are effective permissions?

Effective permissions are the combined permissions permitted and restricted for users and/or groups over a resource. They incorporate NTFS permissions (i.e., explicit permissions and inherited permissions), share permissions, and group permissions collectively to define the actual permissions allocated to a user or group object.

Why is knowing about effective permissions important?

Effective permissions are crucial for several reasons:

• Comprehensive access rights auditing:

  They provide a holistic view of what a user or group can do with a specific resource (i.e., a file or folder) considering all levels of permissions assigned.

• User and group management:

  Effectively managing users and groups with varying levels of permissions becomes simpler for system administrators when utilizing effective permissions.

• Conflict resolution:

  In instances where conflicting permissions exist (i.e., deny and allow permissions) for users or groups, effective permissions provide a clear resolution by determining which permission has taken precedence.

• Troubleshooting and audit access:

  Effective permissions are highly beneficial in resolving access control issues for users encountering difficulties performing specific actions on a resource. They empower administrators to grant the appropriate set of permissions.

• Evaluating security posture:

  Administrators leverage effective permissions to assess the organization's security stance, ensuring the security permissions are aligned with its policies.

• Maintaining IT compliance:

  Organizations should comply with all required regulatory mandates, most of which demand access control and maintaining the principle of least privilege. Failing to meet these exposes organizations to monetary and legal repercussions.

NTFS permissions vs. share permissions

Security permissions can be classified into two groups:

NTFS permissions:

NTFS permissions are a set of access control rights that allow you to define the level of permission (i.e., read, write, execute) for a specific resource, such as the folders and files within Windows NTFS file systems. Two categories of permissions, basic and advanced, can be used to provide additional security to your files and directories. NTFS permissions are further divided into two types based on hierarchy and propagation:

• Explicit permissions: Permissions that are set directly on a file or a folder are called explicit permissions. Assigning explicit permissions for a user object or a group object defines their access rights to a particular object.
• Inherited permissions: Permissions that are inherited from their parent object are called inherited permissions. By default, when a file or folder is created within a parent folder, it inherits the parent object's permissions.

Share permissions:

Share permissions are a set of access control rights that define how a resource shared in the network can be accessed by user and group objects connected to that network in a Windows environment. There are three primary share permissions: read, change, and full control.

It is important to understand that NTFS permissions function differently than share permissions. NTFS permissions are applied exclusively within the local file system, while share permissions take into account both the local file system's permissions and those applied to the shared resource when accessing files and folders via the connected network.

A strategic approach to enhance security for shared folders would be to set the default shared folder permissions for the files and folders, and later, tailor them within NTFS permissions to align with your business needs.

How do effective permissions work?

Some of the essential guidelines used to determine effective permissions are listed below:

• As a general rule, deny permissions hold higher priority than allow permissions.
• For NTFS permissions, explicit permissions take precedence over inherited permissions.
• For inherited permissions, those inherited from the immediate predecessor take precedence over those from a distant predecessor.
• There is a special case scenario where allow permissions take precedence over deny permissions. For instance, a folder with explicit allow permissions can override a folder with inherited deny permissions.
• In cases where a resource is accessed over a network, both NTFS and share permissions will be taken into consideration. In such instances, the most restrictive permissions will prevail for that particular resource. For example: Read (NTFS permission) + full control (share permission) = read (effective permissions).
• In cases where a resource is accessed by a user belonging to two different groups with different NTFS permissions, the least restrictive permissions will prevail for that particular resource. For example: Read (NTFS) + full control (NTFS) = full control (effective permissions).
• Note that no access permission would take precedence over all other permissions for users belonging to two different groups with NTFS permissions. For example: Full control (NTFS) + no access (NTFS) = no access (effective permissions).
• In cases where a resource is accessed by a user belonging to two different groups with different shared folder permissions, the least restrictive permissions will prevail for that particular resource. For example: Read (share) + full control (share) = full control (effective permissions).
• Note that no access permission would take precedence over all other permissions for users belonging to two different groups with shared folder permissions. For example: Full control (NTFS) + no access (NTFS) = no access (effective permissions).