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Date:      Mon, 6 Aug 2018 09:58:57 -0500
From:      Valeri Galtsev <galtsev@kicp.uchicago.edu>
To:        Polytropon <freebsd@edvax.de>
Cc:        Erich Dollansky <freebsd.ed.lists@sumeritec.com>, John Levine <johnl@iecc.com>, thor <thor@irk.ru>, freebsd-questions@freebsd.org
Subject:   Re: Erase memory on shutdown
Message-ID:  <449f6907-9bdf-5459-b9bd-759e62025b02@kicp.uchicago.edu>
In-Reply-To: <20180806154345.3243e993.freebsd@edvax.de>
References:  <20180805150241.1E186200349F8E@ary.qy> <4e70e969-14f7-c65d-96d2-dd1610499cd0@irk.ru> <63033.108.68.162.197.1533484522.squirrel@cosmo.uchicago.edu> <20180806073738.6f459398.freebsd.ed.lists@sumeritec.com> <57043.108.68.162.197.1533514207.squirrel@cosmo.uchicago.edu> <20180806154345.3243e993.freebsd@edvax.de>

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On 08/06/18 08:43, Polytropon wrote:
> On Sun, 5 Aug 2018 19:10:07 -0500 (CDT), Valeri Galtsev wrote:
>>
>> On Sun, August 5, 2018 6:37 pm, Erich Dollansky wrote:
>>> Hi,
>>>
>>> On Sun, 5 Aug 2018 10:55:22 -0500 (CDT)
>>> "Valeri Galtsev" <galtsev@kicp.uchicago.edu> wrote:
>>>
>>>> On Sun, August 5, 2018 10:26 am, thor wrote:
>>>>> https://en.wikipedia.org/wiki/Cold_boot_attack
>>>>>
>>>>
>>>> The trouble is that erasing RAM on clean shutdown does not prevent the
>>>> attacker in the attack as above from still successfully perform the
>>>
>>> so, ECC is also here the only possible answer, at least for parts of it.
>>>
>>> Still, erasing memory when shutting down helps in some cases. I do this
>>> on my machines for small parts when a shutdown is detected. It makes at
>>> least the most obvious attacks from that side difficult.
>>
>> Please, correct me if I am wrong in the following:
>>
>> If the attacker yanks off the power cord, then cold boots off his media,
>> your defense/erasure of memory does not protect you against this attack.
>> Right? Your defense only helps if the attacker does clean shutdown. Right?
> 
> Clearing memory at shutdown time won't happen when
> shutdown time doesn't take place. Many cold boot
> attacks rely on surprisingly (!) interrupting the
> power, which implies physical access, and then
> booting from a custom media, so even clearing
> memory at startup time doesn't happen.
> 
> All those precautions only work when physical access
> is taken out of consideration.

Yes, my point exactly. Thanks!

Valeri

> 
> 

-- 
++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
++++++++++++++++++++++++++++++++++++++++



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