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Re: Default Screen Saver Vulnerability in Microsoft Windows
From: Jason V. Miller (jmillersecurityfocus.com)
Date: Wed May 24 2006 - 17:52:13 CDT
On Wed, May 24, 2006 at 08:52:18PM +0200, Ansgar -59cobalt- Wiechers wrote:
> To be able to write to this registry key or to %SystemRoot%\system32
> administrative or system privileges are required. Why do you believe
> this to be a vulnerability?
To the best of my recollection, this is actually an issue on NT4. In the
event that you opt not to install the screen savers during installation, a
normal user is able to create ``logon.scr'' in ``%systemroot%\system32'',
as the default permissions on this directory include Everyone:Change. This
facilitates local privilege escalation from a normal user to LocalSystem.
At least, that's how I remember it working. I think I mentioned this to
Microsoft around 5 years ago, but they didn't consider it to be a problem.
Jason V. Miller, Threat Analyst
Symantec, Inc. - www.symantec.com