This is used to add users as local admin on a select group of clients.
Needs a input file specified or default to input.txt in same folder.
It converts Administrator SID to friendlyname to account for things such as foreign characters.

It uses WMI to invoke a client side script to be run under admin credentials in order to bypass PSremoting policies.

Content in input should be formatted as below.

Computername,Username
computer1,User1
computer2,User1
computer2,User2

This is used to add users as local admin on a select group of clients.
Needs a input file specified or default to input.txt in same folder.
It converts Administrator SID to friendlyname to account for things such as foreign characters.

It uses WMI to invoke a client side script to be run under admin credentials in order to bypass PSremoting policies.

Content in input should be formatted as below.
Computername,Username
computer1,User1
computer2,User1
computer2,User2
Script below:
[Cmdletbinding()]
Param(
    [String]$InputFile=".\input.txt"
)
$MyPath = Split-Path $MyInvocation.MyCommand.path -Parent
$Logpath = "$MyPath\Status.log"
$Ping = new-object Net.NetworkInformation.Ping
If(!(Test-path -Path $InputFile -PathType Leaf)){Throw{"Could not find $InputFile"}}
$Data = Import-Csv $InputFile -Delimiter ','

$Logpath = "$MyPath\Status.log"
If(!(Test-Path -Path $Logpath -PathType Leaf)){
    New-Item -Path $Logpath -ItemType file
    "Computername,Username,Status" | Out-File $Logpath
}
$LogData = Import-Csv $Logpath -Delimiter ','

Function ConvertTo-Base64($String){
    $Bytes = [System.Text.Encoding]::Unicode.GetBytes($String)
    $Encoded = [System.Convert]::ToBase64String($Bytes)
    Return $Encoded
}
$cmdtemplate = @'
$SID = "S-1-5-32-544" # built-in administrator group sid
# Find Administrator group based on SID and gets the friendlyname of account
$admins = New-object System.Security.Principal.SecurityIdentifier($SID)
[string]$adminNTaccount = $admins.Translate([System.Security.Principal.NTAccount]).Value.Split('\')[1]

# Gets a list of members and collects friendlyname of each member
$computer = [ADSI]('WinNT://.,computer')
$Group = $computer.psbase.children.find($adminNTaccount)
$Group.Add("WinNT://{replacewithuser},user") # Must change/replace user string here with real user account
'@

$data | Foreach-object{
    $Computer = $_.Computername
    $User = $_.Username
    $Cmd = $cmdtemplate -replace '{replacewithuser}',$User
    $EncodedCmd = ConvertTo-Base64($Cmd)
    $EncodedArgs = 'c:\windows\System32\WindowsPowerShell\v1.0\powershell.exe -ExecutionPolicy ByPass -EncodedCommand "' + $EncodedCmd + '"'
    Remove-Variable added -Force -ErrorAction Ignore
    $added = $LogData | Where-Object {($_.Computername -match $computer) -and ($_.Username -match $user) -and ($_.Status -match "Success")}
    $Status = ($Ping.Send($Computer)).Status
    If($added){
        Write-host "Already added $User to $Computer" -ForegroundColor Blue
    }
    ElseIf($Status -eq "Success"){
        $Result = Invoke-WmiMethod -ComputerName $Computer -class win32_process -name create -ErrorAction Ignore -ArgumentList $EncodedArgs
        Write-Verbose $Result
        If($Result.ReturnValue -eq 0){
            Write-host "Added $User to $Computer" -ForegroundColor Green
            $Returnvalue = "Success" 
        }
        Else{
            Write-Host "Failed to add $User to $Computer" -ForegroundColor Red
            $Returnvalue = "Error $($result.ReturnValue)"
        }        
        
    }
    Else{
        Write-Host "Could not contact $Computer" -ForegroundColor Red
        $Returnvalue = "Host Unreachable"
    }

    "$computer,$User,$Returnvalue" | Out-File -Append $Logpath


}
Write-host "Done!" -BackgroundColor Green -ForegroundColor Black
Write-host "Bash the keyboard to quit application!" -BackgroundColor Green -ForegroundColor Black
[void]$Host.UI.RawUI.ReadKey("NoEcho,IncludeKeyDown")