VSC Permissions

Volume Shadow Copies (VSCs) are an essential part of Windows systems, providing the ability to create backup copies or snapshots of files or volumes. Managing access to these snapshots is crucial for security and data integrity. PowerShell offers tools to inspect and manage the permissions of shadow copies, ensuring that only authorized users and processes can access or modify them.

Key Insights:

• Access Management: Permissions on a shadow copy determine which users or groups can access, modify, or delete the snapshots.

• PowerShell Utilization: Get-VssShadowCopy and Get-VssShadowCopyAccess cmdlets in PowerShell are instrumental in listing shadow copies and their permissions.

Overview:

Permissions on VSCs are critical for securing backup data. By default, shadow copies might grant access to system administrators and the SYSTEM account, with more restrictive access for regular users. Understanding and managing these permissions is vital for preventing unauthorized access or modifications to shadow copies.

Listing Shadow Copies:

To list all shadow copies present on the system, use the Get-VssShadowCopy cmdlet. This command provides an overview of existing snapshots, which is the first step in auditing their access permissions.

Checking Permissions:

For a detailed look at the permissions of a specific shadow copy, the Get-VssShadowCopyAccess cmdlet comes into play. It allows administrators to query the access rights of different users and groups to a particular shadow copy.

Example Command:

Get-VssShadowCopyAccess -ID 1

Sample Output Explanation:

• NT AUTHORITY\SYSTEM: This account has full control over the shadow copy, allowing it to perform any action, including modifications and deletions.

• BUILTIN\Administrators: Members of the administrators group also have full control, reflecting their broad access rights on the system.

• BUILTIN\Users: Regular users have read access, enabling them to view the contents of the shadow copy but not modify or delete it.

Practical Use Case:

A security administrator suspects unauthorized access to shadow copies. They use the Get-VssShadowCopy and Get-VssShadowCopyAccess cmdlets to audit the permissions of all snapshots. Discovering overly permissive access, the administrator then takes steps to restrict permissions, ensuring that only essential accounts and groups have the necessary access levels.

Manual Examination:

To manually check VSC permissions:

1. List all shadow copies on the system with Get-VssShadowCopy.

2. For each shadow copy of interest, use Get-VssShadowCopyAccess -ID <ShadowCopyID> to view its permissions.

3. Analyze the output to determine if the access levels are appropriate for your security policies.

Open Source Tools:

While the specific cmdlets Get-VssShadowCopy and Get-VssShadowCopyAccess might not be standard PowerShell commands and could require custom scripts or modules, PowerShell itself is a powerful tool for managing VSC permissions. There are no direct open-source alternatives for these cmdlets, but PowerShell scripts and third-party tools can be developed or used for similar purposes.

Security Considerations:

• Least Privilege: Ensure that shadow copy permissions adhere to the principle of least privilege, limiting full control to essential accounts.

• Monitoring: Implement monitoring for changes to shadow copy permissions to detect unauthorized modifications.