[Full-Disclosure] Re: NetWare Screensaver Authentication Bypass From The Local Console

From: Roger McLaren (RMcLaren_at_vcss.k12.ca.us)
Date: 12/14/04

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    Date: Tue, 14 Dec 2004 13:47:36 -0800
To: <agray@novacoast.com>, <brad@selu.edu>

    This is just another underscore to the fact that physical security is as
    important as any other part of your security infrastructure.

    This vulnerability is present in virtually EVERY operating system if
    you allow a hacker to gain physical access to your server. Whether you
    boot the server from other media to change the Admin password, add an
    account, elevate your privileges, or simply copy the password info to
    crack at your liesure there is always a way if you have physical
    access.

    Just my $.02 worth.

    Roger R. McLaren
    Systems Support Analyst
    Information Technology Services
    Ventura County Superintendent of Schools

    >>> Brad Bendily <brad@selu.edu> 12/14/2004 9:00:57 AM >>>

    As we all know security comes in layers. The only way this exploit
    will
    work is if someone is standing at the server's console. In this way
    all servers are subject to vulnerability and I have discovered this
    method of hacking servers. Ok, not really. But I can tell you that if
    I
    have access to the server console then I can get access to the box.

    This vulnerability is not new, I had to legitimately hack the password
    for a couple of my NetWare servers and I did it 3-4 years ago using
    this same hack. Preferrably I would rather Novell NOT fix this. It's
    a great "just in case" tool.

    I think this is a waste of bandwidth.

    Brad B.

    On Sun, 12 Dec 2004, Adam Gray wrote:

    > Novacoast Security Advisory
    > Novell Netware 5/5.1/6.0/6.5 Vulnerability
    >
    >
    > Synopsis:
    > Novacoast has discovered a vulnerability in the Novell NetWare
    Operating
    > System screen saver software. The vulnerability allows a local
    attacker
    > to bypass authentication and access the system console.
    >
    >
    > Description:
    > The Novell Operating System uses the screen saver nlm with lock
    enabled
    > to protect access to the console. When the screen saver is locked
    only a
    > user in the e-directory tree with supervisor rights to the server
    object
    > has the ability to unlock it. It is possible to bypass this
    > authentication scheme by entering the debugger within NetWare while
    the
    > screensaver is running, kill the screensaver process, and resume the
    > operating system without the screen saver or the access control
    still
    > running.
    >
    > Affected Version:
    > Novell NetWare 5.1
    > Novell Netware 6
    > Novell NetWare 6.5
    >
    > Exploit:
    > with the screensaver nlm running and in enable lock mode press alt
    shift
    > shift esc. Find the screen saver process in memory. Kill it using
    the
    > debugger. If you are not sure how to use the NetWare debugger then
    just
    > kill the server with the q key and restart it without the
    autoexec.ncf
    > running (server -na) edit the autoexec.ncf to keep the screensaver
    from
    > running in the future and restart the server normally. The screen
    saver
    > will not start again.
    >
    > Recommended Solution:
    > Install the Bordermanager ICSA Compliance kit
    > They put the screensaver fix into that patch
    >
    >
    > Status:
    > This bug has been submitted to, acknowledged by, and a fix has been
    > created and included with the Bordermanager ICSA Compliance toolkit.
    >
    > Additional information can be found at the following location:
    > http://support.novell.com/cgi-bin/search/searchtid.cgi?/2969741.htm
    >
    >
    > Disclaimer:
    > Novacoast accepts no liability or responsibility for the
    > content of this report, or for the consequences of any
    > actions taken on the basis of the information provided
    > within. Dissemination of this information is granted
    > provided it is presented in its entirety. Modifications
    > may not be made without the explicit permission of
    > Novacoast.
    >
    >
    > Adam Gray
    > CTO
    > Novacoast, Inc.
    > agray_at_novacoast.com
    > http://www.novacoast.com
    >
    >

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