Get-CurrentProcessIntegrityLevel.ps1

Add-Type -AssemblyName System.ServiceModel
$BF = [Reflection.BindingFlags]::NonPublic -bor [Reflection.BindingFlags]::Static
$C1 = [ServiceModel.PeerNode].Assembly.GetType('System.ServiceModel.Channels.AppContainerInfo')
$C2 = [ServiceModel.PeerNode].Assembly.GetType('System.ServiceModel.Activation.Utility')
$M1 = $C1.GetMethod('GetCurrentProcessToken', $BF)
$M2 = $C2.GetMethod('GetTokenInformation', $BF)
$hT = $M1.Invoke($null, @())
$b = New-Object -TypeName byte[](28)
$M2.Invoke($null, @($hT, 25, [byte[]]$b))
$IL = [Security.Principal.SecurityIdentifier]::new($b, 16).Value

Get-IntegrityLevel.ps1

function Get-IntegrityLevel
{
    param
    (
        [Parameter()]
        [Int32]
        $ProcessId
    )

    try
    {
        $null = [System.ServiceModel.PeerNode]
    }
    catch
    {
        Add-Type -AssemblyName System.ServiceModel
    }

    if($PSBoundParameters.ContainsKey('ProcessId'))
    {
        $processes = Get-Process -Id $ProcessId
    }
    else
    {
        $processes = Get-Process
    }

    foreach($proc in $processes)
    {
        try
        {
            $BindingFlags = [System.Reflection.BindingFlags]::NonPublic -bor [System.Reflection.BindingFlags]::Static
            $UtilityClass = [System.ServiceModel.PeerNode].Assembly.GetType('System.ServiceModel.Activation.Utility')
            $OpenProcessMethod = $UtilityClass.GetMethod('OpenProcessForQuery', $BindingFlags)
            $GetProcessTokenMethod = $UtilityClass.GetMethod('GetProcessToken', $BindingFlags)
            $GetTokenInformationLengthMethod = $UtilityClass.GetMethod('GetTokenInformationLength', $BindingFlags)
            $GetTokenInformationMethod = $UtilityClass.GetMethod('GetTokenInformation', $BindingFlags)

            $hProcess = $OpenProcessMethod.Invoke($null, @($proc.Id))
            $hToken = $GetProcessTokenMethod.Invoke($null, @($hProcess, 8))
            $length = $GetTokenInformationLengthMethod.Invoke($null, @($hToken, 25))
            $bytes = New-Object -TypeName byte[]($length)
            $GetTokenInformationMethod.Invoke($null, @($hToken, 25, [byte[]]$bytes))

            $IntegrityLevel = [Security.Principal.SecurityIdentifier]::new($bytes, 16).Value
        }
        catch
        {
            $IntegrityLevel = $null
        }

        switch($IntegrityLevel)
        {
            S-1-16-0 {$Integrity = 'Untrusted Mandatory Level'}
            S-1-16-4096 {$Integrity = 'Low Mandatory Level'}
            S-1-16-8192 {$Integrity = 'Medium Mandatory Level'}
            S-1-16-8448 {$Integrity = 'Medium Plus Mandatory Level'}
            S-1-16-12288 {$Integrity = 'High Mandatory Level'}
            S-1-16-16384 {$Integrity = 'System Mandatory Level'}
            S-1-16-20480 {$Integrity = 'Protected Process Mandatory Level'}
            S-1-16-28672 {$Integrity = 'Secure Process Mandatory Level'}
            default {$Integrity = $null}
        }

        $props = @{
            ProcessName = $proc.Name
            ProcessId = $proc.Id
            IntegrityLevel = $Integrity
        }

        New-Object -TypeName psobject -Property $props
    }
}