The core difference between WMI and CIM cmdlets in PowerShell lies in their underlying communication protocols for remote management, their security, and their cross-platform compatibility.
While both command sets access the same management data on a Windows system, the older WMI cmdlets use the less-secure, firewall-unfriendly DCOM protocol, while the modern CIM cmdlets primarily use the more efficient and secure WS-Management (WS-Man) protocol. Microsoft has deprecated the WMI cmdlets and recommends using the CIM cmdlets for all new development.
Core conceptual difference
At a foundational level, the distinction is between a standard and an implementation.
- CIM (Common Information Model): CIM is an open, industry-standard data model created by the Distributed Management Task Force (DMTF). It defines how managed components (hardware, software, services) are represented in a platform-agnostic way.
- WMI (Windows Management Instrumentation): WMI is Microsoft's implementation of the CIM standard for the Windows platform. All the management data you access on a Windows system, whether with WMI or CIM cmdlets, is stored in the WMI repository, which adheres to the CIM schema.
Therefore, when you use either a Get-WmiObject or a Get-CimInstance cmdlet, you are ultimately querying the same underlying data. The difference is in how the cmdlet communicates with that data, especially when targeting a remote machine.
Comparison of key features
| Feature | WMI Cmdlets (e.g., Get-WmiObject) |
CIM Cmdlets (e.g., Get-CimInstance) |
|---|---|---|
| Protocol | DCOM (Distributed Component Object Model): An older, Windows-specific protocol that is not firewall-friendly. | WS-Management (WS-Man): A modern, standards-based protocol that is secure and uses standard, static ports (5985 for HTTP, 5986 for HTTPS). |
| Firewall | Difficult to traverse: Uses TCP port 135 and a range of dynamically assigned high-number ports, making firewall configuration complex and less secure. | Easy to traverse: Relies on dedicated ports that are easy to manage and secure. |
| Security | Legacy and less secure: WMI over DCOM is an older security model and has been exploited for lateral network movement by attackers. | Modern and more secure: Integrates with modern authentication protocols like Kerberos and supports encrypted communication. |
| Interoperability | Windows-only: Limited exclusively to managing Windows systems. | Cross-platform: Because CIM is an open standard, the cmdlets can manage other CIM-compliant devices and operating systems, including Linux, that have a compatible CIM server running. |
| Performance | Slower for remote connections: The DCOM architecture is less efficient for enterprise environments, resulting in higher network overhead. | Faster for remote connections: The WS-Man protocol is more optimized, leading to better performance and reduced network overhead. |
| PowerShell Core Support | No support: The legacy WMI cmdlets were never included in PowerShell Core (version 6 and later). | Full support: The CIM cmdlets are available in both Windows PowerShell and PowerShell Core, making them the standard for cross-platform scripting. |
| Sessions | Ad-hoc only: Each remote call establishes a new connection. | Session-based: Supports reusable CIM sessions (New-CimSession), which can significantly increase performance when running multiple commands against the same remote target. |
| Syntax | Less consistent: Older cmdlet design with sometimes verbose syntax. | More consistent: Follows modern PowerShell cmdlet design principles, with a more standardized approach to parameters. |
Practical usage and migration
For anyone writing new PowerShell scripts or modernizing existing ones, the CIM cmdlets are the clear choice. The migration is often straightforward, with a direct cmdlet-to-cmdlet replacement for most common tasks.
Example migration: Getting a process list
Old WMI approach:
Get-WmiObject -Class Win32_Process -ComputerName server01 | Select-Object Name, HandleCount
Use code with caution.
Modern CIM approach:
Get-CimInstance -ClassName Win32_Process -ComputerName server01 | Select-Object Name, HandleCount
Use code with caution.
As you can see, the basic syntax is nearly identical, making the transition painless.
Example with CIM sessions
The real power of CIM appears when managing multiple objects or running multiple commands against a target. Using CIM sessions avoids the overhead of re-establishing a connection for each command.
# Create a CIM session
$session = New-CimSession -ComputerName 'server01'
# Run multiple commands using the established session
Get-CimInstance -ClassName Win32_Process -CimSession $session | Select-Object Name
Get-CimInstance -ClassName Win32_OperatingSystem -CimSession $session
# Remove the session when done
Remove-CimSession $session
Use code with caution.
Conclusion
While WMI cmdlets and CIM cmdlets access the same underlying management data, the CIM cmdlets represent a significant advancement in PowerShell's remote management capabilities. With superior security, better performance, cross-platform compatibility, and a more modern design, CIM is the recommended standard for all modern scripting tasks. The WMI cmdlets are effectively deprecated and should only be used in legacy scripts where compatibility is the sole concern.