Gets a certificate from a webserver and returns AIA and CDP FQDNs. Note, does not do OCSP.

Get-CertificateAIACDP.ps1

New-Variable -Name 'OIDCDP' -Value '2.5.29.31' -Option ReadOnly -Force
New-Variable -Name 'OIDAIA' -Value '1.3.6.1.5.5.7.1.1' -Option ReadOnly -Force
#New-Variable -Name 'OIDAIAOCSP' -Value '1.3.6.1.5.5.7.48.1' -Option ReadOnly -Force

Function Get-RemoteTLSCertificate
{
    param (
        [Parameter(Mandatory=$true)]
        [string]
        $Hostname,
    
        [int]
        $Port = 443
    )
    
    $Certificate = $null
    $TcpClient = New-Object -TypeName System.Net.Sockets.TcpClient
    try {
    
        $TcpClient.Connect($Hostname, $Port)
        $TcpStream = $TcpClient.GetStream()
    
        $Callback = { param($sender, $cert, $chain, $errors) return $true }
    
        $TlsStream = New-Object -TypeName System.Net.Security.SslStream -ArgumentList @($TcpStream, $true, $Callback)
        try {
    
            $TlsStream.AuthenticateAsClient('')
            $Certificate = $TlsStream.RemoteCertificate
    
        } finally {
            $TlsStream.Dispose()
        }
    
    } finally {
        $TcpClient.Dispose()
    }
    
    if ($Certificate) {
        if ($Certificate -isnot [System.Security.Cryptography.X509Certificates.X509Certificate2]) {
            $Certificate = New-Object -TypeName System.Security.Cryptography.X509Certificates.X509Certificate2 -ArgumentList $Certificate
        }
    
        return $Certificate
    }
}

function Get-IssuerCertificate
{
    param(
        [Parameter(Mandatory=$true)]
        [System.Security.Cryptography.X509Certificates.X509Certificate2]
        $X509Certificate
    )

    foreach ($ext in $X509Certificate.Extensions)
    {
        if ($ext.Oid.Value -match $OIDAIA)
        {
            # Try to download the AIA certificate to memory and validate using a recursive call

            $wc = New-Object -TypeName System.Net.WebClient
            

            foreach ($val in $($ext.Format($false) | Select-String '(http[s]?)(:\/\/)([\w\.]+)(\/)([^.]+)(\.[\w\d]+)' -AllMatches).Matches)
            {
                    [byte[]]$certbytes = $wc.DownloadData($val.Value)
                    $parentCert = New-Object "System.Security.Cryptography.X509Certificates.X509Certificate2" -ArgumentList @(,$certbytes)
                    if ($parentCert)
                    {
                        break
                    }
            }
            
            $wc.Dispose()
            if ($parentCert) {
                return $parentCert
            }
            else {
                return $null
            }
        }
    }
}

function Get-CertificateAIACDPProps
{
    param(
        [Parameter(Mandatory=$true)]
        [System.Security.Cryptography.X509Certificates.X509Certificate2]
        $X509Certificate,
        [Parameter(Mandatory=$true)]
        [string]
        $OID
    )
    
    Remove-Variable -Name 'cert' -Force -ErrorAction SilentlyContinue

    $fqdns = @()

    foreach ($ext in $X509Certificate.Extensions)
    {
        # List all FQDNs in the CDP and AIA extensions
        if ($ext.Oid.Value -match $OID)
        {
            #foreach ($val in $($ext.Format($false) | Select-String '(http[s]?)(:\/\/)([^\s\)]+)' -AllMatches).Matches)
            foreach ($val in $($ext.Format($false) | Select-String '(?<=http:\/\/)([\w\.]+)(?=[\/]|[)\.\s]|$)' -AllMatches).Matches)
            {   
 
                if ($fqdns -notcontains $val.Value)
                {
                    $fqdns += $val.Value
                }
                
            }
        }
    }

    return $fqdns
}

$webserver = "www.microsoft.com"

$cert = Get-RemoteTLSCertificate -Hostname $webserver
#$c.Extensions | Format-Table @{Label = "OID"; Expression={$_.Oid.Value}}, @{Label="FriendlyName"; Expression={$_.Oid.FriendlyName}}, @{Label = "ASN1DecodedData"; Expression={$_.format($false)}}

Write-Output "=== Getting AIA/CDP FQDNs from $($webserver) ==="
$cdp = Get-CertificateAIACDPProps -X509Certificate $cert -OID $OIDCDP
$aia = Get-CertificateAIACDPProps -X509Certificate $cert -OID $OIDAIA
Write-Output ">>CDP:"
Write-Output $cdp
Write-Output ">>AIA:"
Write-Output $aia

$cert = Get-IssuerCertificate -X509Certificate $cert

Do {
    Write-Output `n
    Write-Output "=== Getting AIA/CDP FQDNs from $($cert.Subject) ==="
    $cdp = Get-CertificateAIACDPProps -X509Certificate $cert -OID $OIDCDP
    $aia = Get-CertificateAIACDPProps -X509Certificate $cert -OID $OIDAIA
    Write-Output ">>CDP:"
    Write-Output $cdp
    Write-Output ">>AIA:"
    Write-Output $aia
    $cert = Get-IssuerCertificate -X509Certificate $cert
} until ($cert -eq $null)