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Date:      Sun, 19 Jul 1998 16:17:45 -0600
From:      Brett Glass <brett@lariat.org>
To:        Alfred <perlsta@fs3.ny.genx.net>
Cc:        security@FreeBSD.ORG
Subject:   Re: The 99,999-bug question: Why can you execute from the stack?
Message-ID:  <199807192217.QAA03542@lariat.lariat.org>
In-Reply-To: <Pine.SOL.4.00.9807191735350.28070-100000@fs3.ny.genx.net>
References:  <199807192047.OAA02264@lariat.lariat.org>

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It could be a kernel option: "Turn off at your own risk."

--Brett

At 05:37 PM 7/19/98 -0400, Alfred wrote:
 
>there was a thread about this just a week ago, it was something to do with
>signals and threads.  and breakage of some ancient programs.
>
>-Alfred
>
>also there was just an announcement about some package to "self-check"
>executables for stack corruption.
>
>On Sun, 19 Jul 1998, Brett Glass wrote:
>
>> We're going to be spending about a man-month rebuilding a complex system
>> that was hacked due to a buffer overflow exploit. Looking back at our
>> system log files, I can see exactly how the hack was done and how the
>> perpetrator was able to get root.
>> 
>> What I CAN'T understand is why FreeBSD allows the hack to occur. Why on
>> Earth would one want to allow code to be executed from the stack? The Intel
>> segmentation model normally prevents this, and there's additional hardware
>> in the MMU that's supposed to be able to preclude it. Why does the OS leave
>> this gigantic hole open? Why not just close it?
>> 
>> --Brett Glass
>> 
>> 
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