How do I overwrite RAM with Random Data on shutdown?

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How do I overwrite RAM with Random Data on shutdown?

Postby nsuchy » 2018-05-04 21:57

The Linux distro Tor Tails overwrites your system's RAM with Random Data while shutting data in effort to fight cold boot attacks. Is there a package I could install on Debian which would do this on my primary OS? If so, how can I install and configure this?
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Re: How do I overwrite RAM with Random Data on shutdown?

Postby debiman » 2018-05-06 14:33

how does tails do it?
that's what i would research first. they have a nice wiki.
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Re: How do I overwrite RAM with Random Data on shutdown?

Postby ticojohn » 2018-05-06 14:56

Maybe I am totally ignorant and everybody is being paranoid, but I would love to hear how any real data is retained in dynamic ram after shutdown, and presumed power off. I mean, really folks. Dynamic ram, DDR, needs to have a column address strobe (CAS) periodically in order to retain the data stored on the chips. The refresh rate is probably on the order of a few milliseconds, depending on the size and speed of the chips. Without that CAS refresh signal the data is not going to be retained in any coherent and readable fashion. That being said, if someone had some form of static ram in their system then yes, it would be retained after shutdown.
I'm not irrational, I'm just quantum probabilistic.
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Re: How do I overwrite RAM with Random Data on shutdown?

Postby p.H » 2018-05-06 15:06

@ ticojohn :
https://en.wikipedia.org/wiki/Data_rema ... ata_in_RAM
A study found data remanence in DRAM with data retention of seconds to minutes at room temperature and "a full week without refresh when cooled with liquid nitrogen."
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Re: How do I overwrite RAM with Random Data on shutdown?

Postby ticojohn » 2018-05-06 15:15

p.H wrote:@ ticojohn :
https://en.wikipedia.org/wiki/Data_rema ... ata_in_RAM
A study found data remanence in DRAM with data retention of seconds to minutes at room temperature and "a full week without refresh when cooled with liquid nitrogen."

Oh, I understand that there could be some short term retention, especially if there are enough capacitors to store a charge that could be used by the DDR chips on board refresh circuitry. But we're talking a few seconds to a minute. Am I to suppose that some nefarious person is going to gain access to my computer in a few minutes after I shut it down, or that that same nefarious person is going to come in and immediately immerse my computer in liquid nitrogen? I mean really. IMHO that's pretty extreme paranoia.
I'm not irrational, I'm just quantum probabilistic.
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Re: How do I overwrite RAM with Random Data on shutdown?

Postby acewiza » 2018-05-06 21:38

You might be surprised at some of the over-the-top security requirements I've seen placed on very high level U.S. Government systems. I'll always remember the one time caching disk controllers had to be shipped via special courier with chain-of-custody paperwork, despite like you said, there was literally no "practical" way any data remained on those chips.
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Re: How do I overwrite RAM with Random Data on shutdown?

Postby ticojohn » 2018-05-06 23:14

acewiza wrote:You might be surprised at some of the over-the-top security requirements I've seen placed on very high level U.S. Government systems. I'll always remember the one time caching disk controllers had to be shipped via special courier with chain-of-custody paperwork, despite like you said, there was literally no "practical" way any data remained on those chips.

I can almost kind of sorta imagine taking extreme precautions with extremely sensitive top secret government hardware and data sources. And no, I wouldn't be surprised. I worked for a Government Contractor making MIL SPEC electronic systems. We had to be able to trace components clear back to the source of the silicates, and other materials, used to make the transistors.

But if one has that level of paranoia regarding their home computer then I worry about them. :lol:
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Re: How do I overwrite RAM with Random Data on shutdown?

Postby acewiza » 2018-05-07 14:44

I have no clue as to the newbie's use case. But a dearth of supporting information WRT questions on forums like this is de rigueur. :lol:
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Re: How do I overwrite RAM with Random Data on shutdown?

Postby n_hologram » 2018-05-08 12:29

@OP: thanks for sharing the question. I found it and the comments that ensued to be thought-provoking, even though I doubt I'd ever need or want it.

A superficial Google search revealed another thought-provoking post, the top-rated answer:
https://superuser.com/questions/464297/ ... oot-attack
If you are not using old RAM like DDR2, 512 MB or 1024 MB then you should not be worried about CBA...

For anyone truly concerned about CBA, the commentor suggests using truecrypt in a custom shutdown script. I've never used truecrypt and have no idea if this is a reliable or sensible conclusion. Nevertheless, it looks like there are solutions in this post, and in searches.

Edit: rereading the comment/subcomment chain in the above link, the second-top-poster references a paper about this topic from 2010. It's available on the author's own page: http://flynn.zork.net/~pedro/docs/ieee-hst-2010.pdf
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