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Microsoft Windows NTFS Improper Handler Closing
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SUMMARY
<http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/TechRef/81cc8a8a-bd32-4786-a849-03245d68d8e4.mspx>
NTFS is designed as a reliable file system: it offers data encryption, access
control, and is journaled to protect disk consistency in the event of
unexpected shutdowns.
Lack of proper closing of file handlers with NTFS, allow users to view
restricted files without any permission to view the file content.
DETAILS
Vulnerable Systems:
* Microsoft Windows 2000
* Microsoft Windows XP
* Microsoft Windows Server 2003
NTFS driver's code causes the file system to incorrectly assign disk
blocks to files before they have been initialized. Following a recovery
from a system shutdown, uninitialized data may be visible in files from
previously allocated disk blocks.
Previously, this error condition was believed to be related to system
shutdown timings. BugTraq ID #7386 describes one instance of this bug, in
the case of premature service shutdowns. During more recent testing for
other issues, it was uncovered that a service is not required to observe
the behavior identified in the previous advisory.
The incidences of private data appearing in files can be tied to drivers,
services, even typical user-mode applications. Any time the system is shut
down with a file open for writing, the behavior may occur. There were
several specific cases identified, including power/hardware failures,
kernel STOP (blue screens), or shutdowns initiated with the Win32 API
InitiateSystemShutdown(). The common denominator between these cases is
that open file handles are not closed before the system is shutdown.
Upon reboot, such files may contain data belonging to other users.
Among data observed in lab tests were portions of an Administrator's
purged Internet Explorer cache. In many cases, this data is readable to
users without privileges on the system (such as members of the Users or
Guests groups).
Local unprivileged users may gain access to confidential information that
is stored on affected systems. This may allow access to unrelated services
such as web accounts, or further compromise of the affected system's host
network.
ADDITIONAL INFORMATION
The information has been provided by <mailto:mattmurphy@kc.rr.com>
Matthew Murphy.
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