PowerShell Remoting (PS Remote)

Overview

Windows PowerShell Remoting. Using the WS-Management protocol, Windows PowerShell remoting lets you run any Windows PowerShell command on one or more remote computers.

Authentication

Authentication for Remote Connections - Win32 appsMicrosoftLearn

The following list contains a list of what occurs when a script or application runs under the default credentials:

• Kerberos is the default method of authentication when the client is in a domain and the remote destination string is not one of the following: localhost, 127.0.0.1, or [::1].

• Negotiate is the default method when the client is not in a domain, but the remote destination string is one of the following: localhost, 127.0.0.1, or [::1].

Specifying credentials

Credentials through PowerShell

$passwd = ConvertTo-SecureString "Password123" -AsPlainText -Force
$creds = New-Object System.Management.Automation.PSCredential ("lab\logagent", $passwd)

Get-Credentials

Will popup a promtp to enter user credentials

$creds = Get-Credential

Trusted hosts

Windows by default has an empty TrustedHosts list, a list that contains those remote computers (hosts) that you can remotely manage from a client without authentication.

To run PowerShell commands on a device from a remote computer, we have to add the remote machine to the trusted hosts list of the host machine.

Lazy: Allow all

Set-Item WSMan:\localhost\Client\TrustedHosts * -Force

Specify a host

Set-Item WSMan:localhost\client\trustedhosts -value ServerDC -Force

Enumerating for WinRM administrator access

Get all AD computers

$objSearcher = New-Object System.DirectoryServices.DirectorySearcher
$objSearcher.SearchRoot = New-Object System.DirectoryServices.DirectoryEntry
$objSearcher.Filter = "(&(sAMAccountType=805306369))"
$Computers = $objSearcher.FindAll() | %{$_.properties.dnshostname}

Check for administrator access

Invoke-Command -ScriptBlock {hostname} -ComputerName $Computers -ErrorAction SilentlyContinue

Command examples

Connecting to remote host

One-to-one remoting

If you want your remote session to be interactive, then one-to-one remoting is what you want. This type of remoting is provided via the Enter-PSSession cmdlet.

$creds = Get-Credential
Enter-PSSession -ComputerName dc01 -Credential $creds

One-to-many remoting

Sometimes you may need to perform a task interactively on a remote computer. But remoting is much more powerful when performing a task on multiple remote computers at the same time. Use the Invoke-Command cmdlet to run a command against one or more remote computers at the same time.

Invoke-Command -ComputerName dc01, sql02, web01 {Get-Service -Name W32time} -Credential $Cred

PowerShell Sessions

Similar to the CIM sessions, a PowerShell session to a remote computer can be used to run multiple commands against the remote computer without the overhead of a new session for each individual command.

$session = New-PSSession -ComputerName dc01, sql02, web01 -Credential $Cred

Now we can the variable $session to run persist commands.

Invoke-Command -Session $Session {(Get-Service -Name W32time).Start()}
Invoke-Command -Session $Session {Get-Service -Name W32time}

When you finish remove the sessions

Get-PSSession | Remove-PSSession

Executing script on remote host/s

Invoke-Command -ComputerName Server01, Server02 -FilePath c:\Scripts\DiskCollect.ps1

File transfer

Downloading a file over PS Remote from remote machine

$sess = New-PSSession IT-APPSRV01
Copy-Item -FromSession $sess C:\{file} -Destination C:\Windows\Temp\{file}

Upload a file over PS Remote to remote machine

$sess = New-PSSession IT-APPSRV01
Copy-Item -ToSession $sess C:\Windows\Temp\{file} -Destination C:\{file} 

Using WinRM on Kali PowerShell

Installing PowerShell on Kali

sudo apt install powershell

Enter into PowerShell and install PSWSMan

pwsh
Install-Module PSWSMan -Force
Install-WSMan

Common problems

Problem: Error message about unspecified GSS failure

Enter-PSSession : Connecting to remote server xxx.xxx.xxx.xxx failed with the following error message : acquiring creds with username only failed Unspecified GSS failure. Minor code may provide more information SPNEGO cannot find mechanisms to negotiate For more information, see the about_Remote_Troubleshooting Help topic.

sudo apt install gss-ntlmssp

Problem: Error message about access denied connecting with NTLM

Enter-PSSession : MI_RESULT_ACCESS_DENIED

Solution: Make sure to use -Authentication Negotiate even if this isn’t necessary when remoting from a Windows client.

References

PowerShell remoting - PowerShellMicrosoftLearn

https://thomask.sdf.org/blog/2019/12/15/linux-windows-powershell-remoting-troubleshooting.htmlthomask.sdf.org