launch native windows login credential dialog with winAPI

[drummaniac83]

I'm working on a login/privilege escalation feature that uses domain user/PW and got LDAP authentication figured out, but I was hoping to avoid just using a labview string control for the password entry b/c of security (VI Server, unencrypted, etc). I am trying to call CredUIPromptForWindowsCredentials  and launch the native windows login dialog.  It is a function in the System32\credui.dll but I can't get the parameters right.  I keep getting a return value of A0(160) and no dialog.  I think it is the PCREDUI_INFO type screwing it up. It needs:

DWORD WINAPI CredUIPromptForWindowsCredentials(
_In_opt_    PCREDUI_INFO pUiInfo,
_In_        DWORD        dwAuthError,
_Inout_     ULONG        *pulAuthPackage,
_In_opt_    LPCVOID      pvInAuthBuffer,
_In_        ULONG        ulInAuthBufferSize,
_Out_       LPVOID       *ppvOutAuthBuffer,
_Out_       ULONG        *pulOutAuthBufferSize,
_Inout_opt_ BOOL         *pfSave,
_In_        DWORD        dwFlags
);

I've been told that Rolf would be able to solve this in 30 seconds.  Help me LabVIEW! You're my only hope!

[zou · Accepted solution]

Josh,

It's easier to call it in a wrapper C dll.

I manage to get this window to show up:

George

[Sam_Sharp]

zou, do you have the Login.dll DLL and its source (if you can make it available) - can't run your example without it and it would be good to know what's inside it (it is asking people to enter their username/password after all...) but I'm curious to try it.

[zou]

The dll was striped by the forum.

It's calling CredUIPromptForWindowsCredentials

[drummaniac83]

George,

I figured the C wrapper might be the way to go.  It's quite trival to create the structures and data types required in C/CVI, but very complicated in LabVIEW.  On the lava forum, Rolf K said the issue is probably the pointers inside the struct.  I think his instincts are right.

[zou]

The dll and source code can be download from my dropbox:

https://www.dropbox.com/s/74ccqtt40btxg7j/Login.zip?dl=0

 It's just a demo for the ideal.

Not finished.

[drummaniac83]

Sam,

Inside the C dll you basically have to call 2 windows dll functions which are part of the credui.dll:

CredUnPackAuthenticationBuffer

and

CredUIPromptForWindowsCredentials

The first function unpacks the buffer you receive after calling the first function which pops open the native windows login screen and returns a pointer to the buffer.  Once the buffer is unpacked and you have a string representation of the username and PW you can feed it into a .net function PrincipalConext.ValidateCredentials and get a verification of the username and password.  This method works for both local logins and network logins of certain types (Active directory)

Relavent Links:

https://msdn.microsoft.com/en-us/library/windows/desktop/aa375178(v=vs.85).aspx

https://msdn.microsoft.com/en-us/library/bb154889(v=vs.110).aspx

[Sam_Sharp]

Any chance of building a release version of the DLL? As it's built in debug mode (and I don't have VS2012), it requires the debug libraries (msvcr110d.dll as opposed to msvcr110.dll) to load.

[zou]

Sam,

The link has been updated to include the release version dll.

As I said this dll is not finished, just a demo.  It doesn't return the user input.

Reasons: 1. I 'm sure Josh can finish it; 2. I think the user input should be verified within the dll, and return only a boolean.

 P.S. by the way, VS express version is free.  You can download it from MS.

[jennapark86]

Hi zou,

It looks like the dropbox link is no longer available. Can you re-upload the code?

Thanks,

Jenna