How can I force a LockWorkstation from a Windows Service on Vista?

[Malignonne]

Hello,
I have written a Credential Provider which requires a secure token to be
present. This works fine. I have written a Windows Service which periodically
scans for the secure token presence. This works fine.

HOWEVER ....

What I would like to be able to do is to lock the workstation (go back to
the logon screen) if my Windows Service notices that the secure token is no
longer present.

How can I do this (I've been trawling through the web and haven't found
anything I can use).

I've tried running the Windows Service both as a User and as a LocalService.

Any suggestions would be very gratefully received!

 

[Mark L. Ferguson]

Use this command : %windir%\System32\rundll32.exe user32.dll,LockWorkStation

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Mark L. Ferguson
..

 

[Malignonne]

Thanks Mark,

That was one I had already tried!

The command works fine from a console window, but not from a Windows
Service. For example:

HINSTANCE x = ShellExecute(NULL, NULL, "rundll32.exe",
"user32.dll,LockWorkStation", NULL, 0);

returns x = 42, which indicates success. However, the workstation is not
locked.

It looks like a security problem of some sort (I've tried running the
service as Local Server and a Remote Service too, but there is no change)

Regards
Ben

 

[Mark L. Ferguson]

It's probably a rights problem. Would the command :
shutdown /L /T 00
do anything for you?
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Mark L. Ferguson
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[Malignonne]

This doesn't work either, even if I put it in a bat file and run that.

I agree that it is a rights problem.

The problem is how do I resolve it?!

 

[Mark L. Ferguson]

A shortcut can be set to 'run as administrator' and you could launch the bat
file from that.
bat_file_start.lnk/Properties.
There is probably a way to 'impersonate' in the VB code, but I don't know
that.
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Mark L. Ferguson
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[Malignonne]

Still no joy, I'm afraid. Trying to run the shortcut from the service
returns an error of 2.