ComObject 'Microsoft.Update.Session' omit WSUS?

Question

I'm trying to get information about how up-to-date is windows systems. Information from systemstatus or wmic qfe list sometimes don't give full list of installed hostfixs. So I want to make powershell script which checks if there is available updates for system. My scripts looks like this:

[CmdletBinding()]
Param ()

Begin {
    $UpdateSession = New-Object -ComObject 'Microsoft.Update.Session'
}   

Process {
    $UpdateSearcher = $UpdateSession.CreateUpdateSearcher()
    $SearchResult = $UpdateSearcher.Search("IsInstalled=0 and Type='Software' and IsHidden=0")

    if ($SearchResult.Updates.Count -ne 0) {
        $SearchResult.Updates |Select-Object -Property Title, Description |Format-List
    }   
    else {
        Write-Host 'There are no applicable updates'
    }   
} 

My question is: Do this script checks for new updates from local WSUS or from Microsoft's servers? My goal is: Check updates from Microsoft's servers to omit situation, when WSUS's administrator will drop some important updates.

Answer 1

After a search like yours i found this... if it helps

Function Get-PendingUpdate { 
<#    
  .SYNOPSIS   
    Retrieves the updates waiting to be installed from WSUS   
  .DESCRIPTION   
    Retrieves the updates waiting to be installed from WSUS  
  .PARAMETER Computername 
    Computer or computers to find updates for.   
  .EXAMPLE   
   Get-PendingUpdates 

   Description 
   ----------- 
   Retrieves the updates that are available to install on the local system 
  .NOTES 
  Author: Boe Prox                                           

#> 

#Requires -version 3.0   
[CmdletBinding( 
    DefaultParameterSetName = 'computer' 
    )] 
param( 
    [Parameter(ValueFromPipeline = $True)] 
        [string[]]$Computername = $env:COMPUTERNAME
    )     
Process { 
    ForEach ($computer in $Computername) { 
        If (Test-Connection -ComputerName $computer -Count 1 -Quiet) { 
            Try { 
            #Create Session COM object 
                Write-Verbose "Creating COM object for WSUS Session" 
                $updatesession =  [activator]::CreateInstance([type]::GetTypeFromProgID("Microsoft.Update.Session",$computer)) 
                } 
            Catch { 
                Write-Warning "$($Error[0])" 
                Break 
                } 

            #Configure Session COM Object 
            Write-Verbose "Creating COM object for WSUS update Search" 
            $updatesearcher = $updatesession.CreateUpdateSearcher() 

            #Configure Searcher object to look for Updates awaiting installation 
            Write-Verbose "Searching for WSUS updates on client" 
            $searchresult = $updatesearcher.Search("IsInstalled=0")     

            #Verify if Updates need installed 
            Write-Verbose "Verifing that updates are available to install" 
            If ($searchresult.Updates.Count -gt 0) { 
                #Updates are waiting to be installed 
                Write-Verbose "Found $($searchresult.Updates.Count) update\s!" 
                #Cache the count to make the For loop run faster 
                $count = $searchresult.Updates.Count 

                #Begin iterating through Updates available for installation 
                Write-Verbose "Iterating through list of updates" 
                For ($i=0; $i -lt $Count; $i++) { 
                    #Create object holding update 
                    $Update = $searchresult.Updates.Item($i)
                    [pscustomobject]@{
                        #Computername = $Computer
                        KB = $($Update.KBArticleIDs)
                        Title = $Update.Title
                        Categories = ($Update.Categories | Select-Object -ExpandProperty Name)
                        SecurityBulletin = $($Update.SecurityBulletinIDs)
                        MsrcSeverity = $Update.MsrcSeverity
                        IsDownloaded = $Update.IsDownloaded
                        Url = $($Update.MoreInfoUrls)
                        BundledUpdates = @($Update.BundledUpdates)|ForEach{
                           [pscustomobject]@{
                                Title = $_.Title
                                DownloadUrl = @($_.DownloadContents).DownloadUrl
                            }
                        }
                    } 
                }
            } 
            Else { 
                #Nothing to install at this time 
                Write-Verbose "No updates to install." 
            }
        } 
        Else { 
            #Nothing to install at this time 
            Write-Warning "$($c): Offline" 
        }  
    }
}  

}

thanks to Boe Prox... it is a great script!