Folder audit Powershell script, nested loop - windows

Question

I am trying to get a script working to audit folder permissions on a Windows server, among other data, and export this data to a CSV file for analysis after a ransomware attack.
I ripped the script from a forum, but it did not run correctly as is. Below is a slightly modified version during my troubleshooting.
I am well versed in batch scripting, and have a decent understanding of loops and pipelining, but this Powershell script has me scratching my head.
It seems like the array is not making it to the nested loop.
I am testing in Windows 10 Pro 21H1, using Powershell version 5.1.19041.1320, build 10.0.19041.1320
##The script:
$ErrorActionPreference = "Continue"
$strComputer = $env:ComputerName
$colDrives = Get-PSDrive -PSProvider Filesystem
ForEach ($DriveLetter in $colDrives) {
$StartPath = "$DriveLetter`:\"
Get-ChildItem -LiteralPath $StartPath -Recurse | ?{ $_.PSIsContainer } |
ForEach ($FullPath = Get-Item -LiteralPath{Get-Item -LiteralPath $_.PSPath}{Get-Item -
LiteralPath $FullPath}.Directoryinfo.GetAccessControl())}
Select #{N='Server Name';E={$strComputer}}
#{N='Full Path';E={$FullPath}}
#{N='Type';E={If($FullPath.PSIsContainer -eq $True) {'D'} Else {'F'}}}
#{N='Owner';E={$_.Owner}}
#{N='Trustee';E={$_.IdentityReference}}
#{N='Inherited';E={$_.IsInherited}}
#{N='Inheritance Flags';E={$_.InheritanceFlags}}
#{N='Ace Flags';E={$_.PropagationFlags}}
#{N='Ace Type';E={$_.AccessControlType}}
#{N='Access Masks';E={$_.FileSystemRights}}
Export-CSV -NoTypeInformation -Delimiter "|" -Path "$strComputer`_$DriveLetter.csv"
##The error I am getting:
You cannot call a method on a null-valued expression.
At C:\Users\user\Documents\fileaudit2.ps1:8 char:13
ForEach ($FullPath = Get-Item -LiteralPath{Get-Item -LiteralPath $ ...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CategoryInfo : InvalidOperation: (:) [], RuntimeException
FullyQualifiedErrorId : InvokeMethodOnNull
##when I modify the nested loop as follows:
ForEach ($FullPath = Get-Item -LiteralPath{Get-Item -LiteralPath $_.PSPath}{Get-Item -LiteralPath $FullPath}).Directoryinfo.GetAccessControl()}
##I get the error:
Get-Item : Cannot evaluate parameter 'LiteralPath' because its argument is specified as a script block and there is no input. A script block cannot be evaluated without
input.
At C:\Users\user\Documents\fileaudit2.ps1:8 char:46
... Path = Get-Item -LiteralPath{Get-Item -LiteralPath $_.PSPath}{Get-Ite ...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CategoryInfo : MetadataError: (:) [Get-Item], ParameterBindingException
FullyQualifiedErrorId : ScriptBlockArgumentNoInput,Microsoft.PowerShell.Commands.GetItemCommand
##I'm just wholly struggling to understand what is not working in this loop.

Answer 1

You are mixing a lot of unneeded Get-Item calls in there.
I also would not use Get-PSDrive for this because I assume you don't want to get results for CD drives, USB devices etc in the report.
Try:
# this returns drives WITH a trailing backslash like C:\
$colDrives = ([System.IO.DriveInfo]::GetDrives() | Where-Object { $_.DriveType -eq 'Fixed' }).Name
# or use:
# this returns drives WITHOUT trailing backslash like C:
# $colDrives = (Get-CimInstance -ClassName win32_logicaldisk | Where-Object { $_.DriveType -eq 3 }).DeviceID
$result = foreach ($drive in $colDrives) {
Get-ChildItem -LiteralPath $drive -Directory -Recurse -ErrorAction SilentlyContinue |
ForEach-Object {
$path = $_.FullName
$acl = Get-Acl -Path $path
foreach ($access in $acl.Access) {
[PsCustomObject]#{
Server = $env:COMPUTERNAME
Drive = $drive[0] # just the first character of the drive
Directory = $path
Owner = $acl.Owner
Trustee = $access.IdentityReference
Inherited = $access.IsInherited
InheritanceFlags = $access.InheritanceFlags -join ', '
'Ace Flags' = $access.PropagationFlags -join ', '
'Ace Type' = $access.AccessControlType
'Access Masks' = $access.FileSystemRights -join ', '
}
}
}
}
# now you can save your result as CSV file for instance you can double-click to open in Excel:
$result | Export-Csv -Path 'X:\WhereEver\audit.csv' -NoTypeInformation -UseCulture
To do this on several remote machines, wrap it inside Invoke-Command
# set the credentials for admin access on the servers
$cred = Get-Credential 'Please enter your admin credentials'
# create an array of the servers you need to probe
$servers = 'Server01', 'Server02'
$result = Invoke-Command -ComputerName $servers -Credential $cred -ScriptBlock {
$colDrives = ([System.IO.DriveInfo]::GetDrives() | Where-Object { $_.DriveType -eq 'Fixed' }).Name
foreach ($drive in $colDrives) {
# code inside this loop unchanged as above
}
}
# remove the extra properties PowerShell added
$result = $result | Select-Object * -ExcludeProperty PS*, RunspaceId
# output to csv file
$result | Export-Csv -Path 'X:\WhereEver\audit.csv' -NoTypeInformation -UseCulture