Re: Another Mac OS X ScreenSaver Security Issue (after Security Update 2003-07-14)

From: Gavin Hanover (ghanoverat_private)
Date: Thu Jul 31 2003 - 12:08:14 PDT

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    I don't quite agree. Windows uses control-alt-delete as a security
    device. It binds those keys as a hotkey in such a way that no other
    aplication can replace it. This is why it is used at logon; it
    prevents a user from creating a program that looked like a logon
    prompt, and could bind the control-alt-delete keys to display a
    password prompt. (pressing control-alt-delete in any application
    other than the logon screen would display the "shutdown/logoff/task
    manager" window, at which point you would know not to enter your
    password in any prompt)
    If someone were to find a way to bind to those hotkeys, would you
    then consider this a security issue with Windows? If so, how is
    Apple's failure to block kill calls to the screen saver not a
    security issue?
    
    Gavin
    
    : I agree with Doug White in the assessment that this is, in fact, an
    : issue
    : that is the responsibility of Ambrosia, if it is to be considered a
    : security
    : issue at all. Apple cannot be held responsible for the code of
    third 
    : party
    : developers.
    : 
    : I downplay the definition of this as a security issue at all
    because 
    : there are
    : so many immediate workarounds. One is not running or installing
    Escape 
    : Pod
    : in the first place. Another is simply logging out when you leave
    your 
    : workstation,
    : rather than relying on ScreenSaverEngine for your security. Bottom
    line,
    : there are more direct and more threatening exploits that are
    available 
    : to
    : people who happen upon an OS X machine unattended. Allow me to
    describe
    : a couple of them:
    : 
    : 1) If a user finds a machine unattended, whether running 
    : ScreenSaverEngine
    : or not, and regardless of the presence of Escape Pod on said
    machine, 
    : the
    : machine can be booted from an OS X installation CDROM, at which
    point 
    : the
    : "Reset Password" option can be used to change root access to the 
    : machine,
    : which allows the user to log in as root, then change the password
    for 
    : any account,
    : including whatever account was initially running ScreenSaverEngine.
    : Data can
    : then be removed or overwritten at said user's discretion.
    : 
    : 2) If an unattended machine is discovered, it can also be powered 
    : down, and
    : carried off, physically, without regard to the presence of 
    : ScreenSaverEngine
    : or Escape Pod.
    : 
    : Do these constitute security threats or exploits that are Apple's 
    : responsibility
    : to protect against? Of course not. Both are common sense examples
    of 
    : how many
    : security measures can be circumvented using simple, direct
    techniques. 
    : Neither
    : implies that anyone at Apple should be recoding the operating
    system, 
    : or any of
    : it's underlying core technologies in order to prevent them from
    being 
    : used.
    : 
    : Beispiel: If the rightful user/administrator of any given OS X
    machine 
    : were to install
    : the following shell script, how would it be Apple's responsibility
    to 
    : prevent this?
    : 
    : #!/bin/sh
    : while true
    : do
    :          killall ScreenSaverEngine
    :          sleep 60
    : done
    : 
    : 
    : -
    : m a t t h e w  n .  s h a r p
    : mns(at)mnslab.com
    
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