Get Cached Credentials in PowerShell from Windows 7 Credential Manager

Question

Can I do this with some API I am overlooking or do I have to figure out porting the C# .NET API calls mentioned here into PowerShell to make this happen in a script?

Answer 1

You can use Add-Type cmdlet to easily port it I believe:

$sig = @"

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct NativeCredential
{
    public UInt32 Flags;
    public CRED_TYPE Type;
    public IntPtr TargetName;
    public IntPtr Comment;
    public System.Runtime.InteropServices.ComTypes.FILETIME LastWritten;
    public UInt32 CredentialBlobSize;
    public IntPtr CredentialBlob;
    public UInt32 Persist;
    public UInt32 AttributeCount;
    public IntPtr Attributes;
    public IntPtr TargetAlias;
    public IntPtr UserName;

    internal static NativeCredential GetNativeCredential(Credential cred)
    {
        NativeCredential ncred = new NativeCredential();
        ncred.AttributeCount = 0;
        ncred.Attributes = IntPtr.Zero;
        ncred.Comment = IntPtr.Zero;
        ncred.TargetAlias = IntPtr.Zero;
        ncred.Type = CRED_TYPE.GENERIC;
        ncred.Persist = (UInt32)1;
        ncred.CredentialBlobSize = (UInt32)cred.CredentialBlobSize;
        ncred.TargetName = Marshal.StringToCoTaskMemUni(cred.TargetName);
        ncred.CredentialBlob = Marshal.StringToCoTaskMemUni(cred.CredentialBlob);
        ncred.UserName = Marshal.StringToCoTaskMemUni(System.Environment.UserName);
        return ncred;
    }
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct Credential
{
    public UInt32 Flags;
    public CRED_TYPE Type;
    public string TargetName;
    public string Comment;
    public System.Runtime.InteropServices.ComTypes.FILETIME LastWritten;
    public UInt32 CredentialBlobSize;
    public string CredentialBlob;
    public UInt32 Persist;
    public UInt32 AttributeCount;
    public IntPtr Attributes;
    public string TargetAlias;
    public string UserName;
}

public enum CRED_TYPE : uint
    {
        GENERIC = 1,
        DOMAIN_PASSWORD = 2,
        DOMAIN_CERTIFICATE = 3,
        DOMAIN_VISIBLE_PASSWORD = 4,
        GENERIC_CERTIFICATE = 5,
        DOMAIN_EXTENDED = 6,
        MAXIMUM = 7,      // Maximum supported cred type
        MAXIMUM_EX = (MAXIMUM + 1000),  // Allow new applications to run on old OSes
    }

public class CriticalCredentialHandle : Microsoft.Win32.SafeHandles.CriticalHandleZeroOrMinusOneIsInvalid
{
    public CriticalCredentialHandle(IntPtr preexistingHandle)
    {
        SetHandle(preexistingHandle);
    }

    public Credential GetCredential()
    {
        if (!IsInvalid)
        {
            NativeCredential ncred = (NativeCredential)Marshal.PtrToStructure(handle,
                  typeof(NativeCredential));
            Credential cred = new Credential();
            cred.CredentialBlobSize = ncred.CredentialBlobSize;
            cred.CredentialBlob = Marshal.PtrToStringUni(ncred.CredentialBlob,
                  (int)ncred.CredentialBlobSize / 2);
            cred.UserName = Marshal.PtrToStringUni(ncred.UserName);
            cred.TargetName = Marshal.PtrToStringUni(ncred.TargetName);
            cred.TargetAlias = Marshal.PtrToStringUni(ncred.TargetAlias);
            cred.Type = ncred.Type;
            cred.Flags = ncred.Flags;
            cred.Persist = ncred.Persist;
            return cred;
        }
        else
        {
            throw new InvalidOperationException("Invalid CriticalHandle!");
        }
    }

    override protected bool ReleaseHandle()
    {
        if (!IsInvalid)
        {
            CredFree(handle);
            SetHandleAsInvalid();
            return true;
        }
        return false;
    }
}

[DllImport("Advapi32.dll", EntryPoint = "CredReadW", CharSet = CharSet.Unicode, SetLastError = true)]
public static extern bool CredRead(string target, CRED_TYPE type, int reservedFlag, out IntPtr CredentialPtr);

[DllImport("Advapi32.dll", EntryPoint = "CredFree", SetLastError = true)]
public static extern bool CredFree([In] IntPtr cred);


"@
Add-Type -MemberDefinition $sig -Namespace "ADVAPI32" -Name 'Util'

$targetName = "computer"
$nCredPtr= New-Object IntPtr

$success = [ADVAPI32.Util]::CredRead($targetName,1,0,[ref] $nCredPtr)

if($success){
    $critCred = New-Object ADVAPI32.Util+CriticalCredentialHandle $nCredPtr
    $cred = $critCred.GetCredential()
    $password = $cred.CredentialBlob;
    write-host -fore blue $password
}

Adapted from here: http://social.technet.microsoft.com/Forums/en-US/ITCG/thread/e91769eb-dbce-4e77-8b61-d3e55690b511/

Based on: http://blogs.msdn.com/b/peerchan/archive/2005/11/01/487834.aspx