#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- generated fix script

    Fault : Certificate enrolment fails -- template permissions and CA errors
    Fix   : Set the template permissions correctly
    Source: https://jbtecwiz.com/support/srv-app-ca-enrollment

    Run as     : Certificate Templates console
    Expect     : 30 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    The request is denied.

    HOW TO UNDO IT
    Permission changes are reversible in the same console.

    This script walks the fix one step at a time and asks before each
    one. Steps with no command are things you do yourself -- it prints
    those and waits. Run with -DryRun to print without executing.

    --------------------------------------------------------------------
    NO WARRANTY - USE AT YOUR OWN RISK

    This script is provided by JbTecWiz as-is and with no warranty of any
    kind, express or implied. You run it entirely at your own risk.

    JbTecWiz accepts no liability for any loss or damage arising from its
    use, including but not limited to data loss, downtime, or configuration
    changes that turn out to be wrong for your system.

    You are responsible for reading this script before running it, for
    satisfying yourself that it suits the machine in front of you, and for
    having a working backup first. Some steps cannot be undone.
    --------------------------------------------------------------------
#>

[CmdletBinding()]
param(
    # Print every step and command without running anything.
    [switch]$DryRun,
    # Do not ask before each step. Read the script first if you use this.
    [switch]$Unattended
)

$ErrorActionPreference = 'Stop'
$script:Failed = 0

function Write-Rule { param([string]$Text)
    Write-Host ''
    Write-Host ('-' * 70) -ForegroundColor DarkGray
    if ($Text) { Write-Host $Text -ForegroundColor Cyan }
}

function Show-Prose { param([string]$Text, [string]$Colour = "Gray")
    if (-not $Text) { return }
    $words = $Text -split "\s+"; $line = "  "
    foreach ($w in $words) {
        if (($line.Length + $w.Length) -gt 74) { Write-Host $line -ForegroundColor $Colour; $line = "  " }
        $line += "$w "
    }
    if ($line.Trim()) { Write-Host $line -ForegroundColor $Colour }
}

function Invoke-Step {
    param(
        [int]$Number, [string]$Do, [string]$Why,
        [scriptblock]$Command, [switch]$Manual, [string]$Shell = "powershell"
    )
    Write-Rule "  Step $Number of 5"
    Show-Prose $Do "White"
    if ($Why) { Write-Host ""; Show-Prose $Why "DarkGray" }

    if ($Manual) {
        Write-Host ''
        Write-Host '  -> Do this yourself, then press Enter to carry on.' -ForegroundColor Yellow
        if (-not $Unattended -and -not $DryRun) { [void](Read-Host) }
        return
    }

    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor Green
    }
    Write-Host ''

    if ($DryRun) { Write-Host "  (dry run -- not executed)" -ForegroundColor DarkGray; return }
    if (-not $Unattended) {
        $a = Read-Host "  Run this step? [Y]es / [S]kip / [Q]uit"
        if ($a -match "^[Qq]") { Write-Host "  Stopped at your request."; exit 0 }
        if ($a -match "^[Ss]") { Write-Host "  Skipped." -ForegroundColor DarkGray; return }
    }
    try { & $Command }
    catch {
        $script:Failed++
        Write-Host ("  Step $Number failed: " + $_.Exception.Message) -ForegroundColor Red
        Show-Prose "The rest of the fix may depend on this. Read the write-up before carrying on." "Red"
        if (-not $Unattended) {
            $c = Read-Host "  Carry on anyway? [y/N]"
            if ($c -notmatch "^[Yy]") { exit 1 }
        }
    }
}

Write-Rule
Write-Host '  Certificate enrolment fails -- template permissions and CA errors' -ForegroundColor White
Write-Host '  Set the template permissions correctly' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   30 minutes'
Write-Host ''
Show-Prose 'No warranty. Use at your own risk - JbTecWiz accepts no liability. Read it before you run it, and have a backup.' 'DarkYellow'
Write-Rule

if (-not $Unattended -and -not $DryRun) {
    $go = Read-Host '  Ready? [y/N]'
    if ($go -notmatch "^[Yy]") { Write-Host "  Nothing was changed."; exit 0 }
}

Invoke-Step -Number 1 -Do 'Read the denial on the client -- it names what was missing.' -Command {
    Get-WinEvent -LogName Application -MaxEvents 40 | Where-Object { $_.Id -in 13,22 } | Format-List TimeCreated,Id,Message
}

Invoke-Step -Number 2 -Do 'Open the Certificate Templates console, find the template, and check the Security tab. The requester needs Read and Enroll, and Autoenroll as well if it is to enrol automatically.' -Why 'Read and Enroll without Autoenroll produces a template that works when requested by hand and never issues automatically -- which is exactly the confusing half-working state most of these reports describe.' -Command {
    certtmpl.msc
}

Invoke-Step -Number 3 -Do 'Never grant Enroll to Domain Users on a template that allows the subject name to be supplied in the request. That combination lets any user request a certificate in anybody''s name.' -Why 'This is the ESC1 misconfiguration and it is a full domain-compromise path, not a theoretical concern. It is worth checking every template for it while you are here.' -Manual

Invoke-Step -Number 4 -Do 'Audit the templates for that combination.' -Command {
    Get-ADObject -SearchBase "CN=Certificate Templates,CN=Public Key Services,CN=Services,$((Get-ADRootDSE).configurationNamingContext)" -Filter * -Properties msPKI-Certificate-Name-Flag,msPKI-Enrollment-Flag,displayName | Where-Object { $_.'msPKI-Certificate-Name-Flag' -band 1 } | Format-Table displayName
}

Invoke-Step -Number 5 -Do 'Check the CA''s own permissions allow the requester to request certificates at all.' -Command {
    certutil -getreg CA\Security
}

Write-Rule "  Confirm it worked"
Show-Prose 'The certificate is issued to the intended requester and to nobody who should not have it.' 'White'
Write-Host ''
if (-not $DryRun) {
    certutil -view -restrict "Disposition=20" -out "RequestID,CommonName,CertificateTemplate,NotAfter" | Select-Object -Last 20
}

Write-Rule
if ($script:Failed -gt 0) {
    Write-Host ("  Finished with " + $script:Failed + " failed step(s).") -ForegroundColor Yellow
    Show-Prose 'Read the full write-up at https://jbtecwiz.com/support/srv-app-ca-enrollment' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Permission changes are reversible in the same console.' 'DarkGray'
Write-Rule