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Protecting a Laptop From Sophisticated Attacks

Soulskill posted about 3 years ago | from the living-inside-a-faraday-cage-doesn't-count dept.

Security 169

mike_cardwell sends in a detailed writeup of how he went about protecting a Ubuntu laptop from attacks of varying levels of sophistication, covering disk encryption, defense against cold boot attacks, and even simple smash-and-grabs. (He also acknowledges that no defense is perfect, and the xkcd password extraction tool would still work.) Quoting: "An attacker with access to the online machine could simply hard reboot the machine from a USB stick or CD containing msramdmp to grab a copy of the RAM. You could password protect the BIOS and disable booting from anything other than the hard drive, but that still doesn't protect you. An attacker could cool the RAM, remove it from the running machine, place it in a second machine and boot from that instead. The first defense I used against this attack is procedure based. I shut down the machine when it's not in use. My old Macbook was hardly ever shut down, and lived in suspend to RAM mode when not in use. The second defense I used is far more interesting. I use something called TRESOR. TRESOR is an implementation of AES as a cipher kernel module which stores the keys in the CPU debug registers, and which handles all of the crypto operations directly on the CPU, in a way which prevents the key from ever entering RAM. The laptop I purchased works perfectly with TRESOR as it contains a Core i5 processor which has the AES-NI instruction set."

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This just reminds me of... (-1, Redundant)

barlevg (2111272) | about 3 years ago | (#37222958)

Re:This just reminds me of... (2)

stillnotelf (1476907) | about 3 years ago | (#37222974)

I must be new here, I thought it was traditional to at least RTFS, if not RTFA.

Re:This just reminds me of... (1, Funny)

barlevg (2111272) | about 3 years ago | (#37223022)

Oh, ha! No, I'm just a really bad skimmer today...

I'm tempted to mod that funny (0)

Anonymous Coward | about 3 years ago | (#37223124)

Just because of the utter fail.

Re:This just reminds me of... (2)

toastar (573882) | about 3 years ago | (#37223684)

<quote>I must be new here, I thought it was traditional to at least RTFS, if not RTFA.</quote>

Your not the new one.... someone needs to tell Soulskill the obligatory XKCD belongs in the comments not the summary.

Jeez, taco's gone for one day and posters start slacking.

Re:This just reminds me of... (-1)

Anonymous Coward | about 3 years ago | (#37223016)

... Did you not notice the link to that very comic in the summary...?

Re:This just reminds me of... (1, Funny)

barlevg (2111272) | about 3 years ago | (#37223104)

Did you not notice the reply right above yours?

Re:This just reminds me of... (0, Offtopic)

Anonymous Coward | about 3 years ago | (#37223778)

Did you not notice the reply right above yours?

No, I didn't. Because as of when I loaded the story, it did not exist. Notice that there is only a 2 minute difference between their post and mine.

Re:This just reminds me of... (2)

netsharc (195805) | about 3 years ago | (#37223042)

Gee, I wonder how that link got planted into your mind...

INCEPTION

Re:This just reminds me of... (0)

Anonymous Coward | about 3 years ago | (#37223764)

weird... i'm watching Inception right now, while reading this post.

...at least that's what i _think_ is going on....

Re:This just reminds me of... (0)

Anonymous Coward | about 3 years ago | (#37223084)

I'm so sick of that comic, with deniable encryption [wikipedia.org] implementations like those found in TrueCrypt you can be quite effective against such an attacker.

Re:This just reminds me of... (1)

TheSpoom (715771) | about 3 years ago | (#37223126)

Unless they know what they want and don't find it in your primary encrypted drive, in which case they'll continue to beat you. What, you don't think they also know about plausibly deniable encryption?

Re:This just reminds me of... (2)

Applekid (993327) | about 3 years ago | (#37223232)

Unless they know what they want and don't find it in your primary encrypted drive, in which case they'll continue to beat you. What, you don't think they also know about plausibly deniable encryption?

With pretty much every nation either already being a police state or quickly becoming one, I don't see any scenario in which they would actually avoid the sadistic pleasure of beating on a suspect, whether or not they really think they could get what they want.

Re:This just reminds me of... (1)

INT_QRK (1043164) | about 3 years ago | (#37223346)

Axiom 1: The cost of security must never exceed the value of the asset. Just saying.

Re:This just reminds me of... (0)

EXrider (756168) | about 3 years ago | (#37223534)

Let me put my tinfoil hat on for a moment... Beatings aren't necessary, the US gov't can simply use the NSAKEY [google.com] to decrypt anything encrypted using Microsoft libraries, this was revealed back in NT4 and again when Win2k SP2 source code was leaked. This is to make their encryption methods export compliant. This is the only legit news article [bbc.co.uk] I could dig up on it right now, but if you look around, I'm sure you'll find more. Pretty sure I read somewhere that there's another "unknown" key out there that they think is for the UK gov't to use as well; actually that might be what was revealed in the SP2 source code leak.

Re:This just reminds me of... (0)

Anonymous Coward | about 3 years ago | (#37223240)

That's just a problem of data rather then the mechanism, the whole point of deniable encryption is they can't prove it exists, from that point you have to use that to your advantage. Also, in most scenarios involving an attacker like that it's more likely going to be law enforcement using court orders to compel you to hand over keys, in a scenario against law enforcement deniable encryption definitely starts to have real world practicality. These days, I think it's more likely that someone is going to be attacked with a criminal or civil court order rather then a wrench when it comes to seizing data.

Re:This just reminds me of... (1)

Riceballsan (816702) | about 3 years ago | (#37223260)

I would imagine that would take a combination of your bluffing skills, and the stregnth of your hoax. Say you have a laptop with 500,000 SSN's on them, you mirror the fake to be exactly like the real, except then you have it randomize all of the SSNs. Now of course you then need to get the heck out of town as soon as they can confirm that you have tricked them.

Re:This just reminds me of... (1, Informative)

chill (34294) | about 3 years ago | (#37223302)

Fairly easy to detect, if you have access to the target machine multiple times.

Take bit-level snapshot of hard drive on first visit.

On subsequent visits, take bit-level snapshots and compare them. If the "random" data changes between snapshots, then something is touching it and your plausibility goes out the window.

Re:This just reminds me of... (0)

Anonymous Coward | about 3 years ago | (#37223704)

You're assuming the data changes often if at all.

And all of this effort will not protect you from (3, Funny)

Anonymous Coward | about 3 years ago | (#37222972)

The real enemy, which is the alien space zebra vampires that are out to suck your blood.

Seriously, this much effort is excessive considering the value of what anybody in a normal situation should have on their laptop. If you have a genuine need for this, you should be on the level of the person carrying the Football, and as such, you would be better investing in the Secret Service equivalent.

Re:And all of this effort will not protect you fro (3, Insightful)

CadentOrange (2429626) | about 3 years ago | (#37223068)

I agree that it's just too much hassle to go through to secure a standard laptop. It's still an interesting experiment and it neatly lays out the attack vectors and potential counters.

Re:And all of this effort will not protect you fro (1)

idontgno (624372) | about 3 years ago | (#37223086)

Yes.

TFA's a fine intellectual exercise, but as explicitly pointed out, the willingness to commit kidnapping and inflict torture rather pathetically trumps all of that.

Interesting. Not completely practical, but interesting.

Re:And all of this effort will not protect you fro (1)

kylemonger (686302) | about 3 years ago | (#37223190)

Willingless to kidnap and commit torture is not trumped if you're dealing with law enforcement. If they gotten to the point where their only remaining option is beating the information out of you, then you've won, assuming our legal system has any remaining value. Evidence that flows from that beating isn't going to be admissible in court. And why would an ordinary citizen want to hide information from law enforcement? Malum prohibitum [wikipedia.org] .

Re:And all of this effort will not protect you fro (1)

BitZtream (692029) | about 3 years ago | (#37223418)

In general, when law enforcement has an instance where someone won't give up a password, they just put you in jail anyway, effectively that is just as good as finding you guilty, either way, you end up in jail. You lose.

Re:And all of this effort will not protect you fro (0)

Anonymous Coward | about 3 years ago | (#37223560)

In general, when law enforcement has an instance where someone won't give up a password, they just put you in jail anyway, effectively that is just as good as finding you guilty, either way, you end up in jail. You lose.

If they're set on it, there's nothing you can say that will change an officer's mind about putting you in jail once they've decided they're going to. Give them all the passwords you want. Refuse them. It doesn't really matter.

Incidentally, whenever you ask a lawyer if they've ever had a case helped by the client opening his mouth to police investigators, they just start laughing. Opening your mouth, even about a password, even if you're TRYING to help, cannot possibly help you.

Re:And all of this effort will not protect you fro (1)

kylemonger (686302) | about 3 years ago | (#37223732)

To jail you they will have to charge you with something, typically contempt of court or obstruction. Neither of these is a felony where I live and the prison terms are modest. Meaning that once released you'd still be young, able to vote, carry a firearm and get a job. Plus by standing up for your privacy you might help change the society we live in.

Re:And all of this effort will not protect you fro (1)

Imrik (148191) | about 3 years ago | (#37223802)

In the US at least, contempt of court has a prison term of 'until you comply with the court order.'

Re:And all of this effort will not protect you fro (1)

networkBoy (774728) | about 3 years ago | (#37223860)

Still untested for all practical purposes, but...
The fifth amendment here in the US *should* protect you from being compelled to give up passwords that are not written down, including punishment via contempt of court.
-nB

Re:And all of this effort will not protect you fro (1)

Squiddie (1942230) | about 3 years ago | (#37224172)

That's still being debated. It depends on the circumstances. It's a new thing for the courts to deal with, and we can all see where this is going.

Re:And all of this effort will not protect you fro (1)

networkBoy (774728) | about 3 years ago | (#37224216)

Failing that you take the Screwed less test:
Will disclosing the key screw me more or less than keeping it secret?
If the answer is less, well, give up the key.
If it is more give up the key with a typo or two.
(Ollie North style)
"I'm sorry sir I don't recall"

Re:And all of this effort will not protect you fro (1)

kylemonger (686302) | about 3 years ago | (#37224004)

Federal judges can jail you forever. Terms vary in state courts.

Re:And all of this effort will not protect you fro (1)

RKBA (622932) | about 3 years ago | (#37223678)

What has happened in the past (and was reported on in the news a few weeks ago), is that a judge orders you to divulge the password(s) and if you refuse he sentences you to contempt of court and keeps you in jail/prison until you do reveal the passwords.

Re:And all of this effort will not protect you fro (1)

networkBoy (774728) | about 3 years ago | (#37223868)

Really?
Where was this?

Re:And all of this effort will not protect you fro (1)

Reelin (2447528) | about 3 years ago | (#37224204)

What has happened in the past (and was reported on in the news a few weeks ago), is that a judge orders you to divulge the password(s) and if you refuse he sentences you to contempt of court and keeps you in jail/prison until you do reveal the passwords.

...

[citation needed]

Re:And all of this effort will not protect you fro (2)

Tetsujin (103070) | about 3 years ago | (#37223358)

Yes.

TFA's a fine intellectual exercise, but as explicitly pointed out, the willingness to commit kidnapping and inflict torture rather pathetically trumps all of that.

Interesting. Not completely practical, but interesting.

Well, it depends on how you define practical - and what kind of situation you're in.

I mean, if it were my laptop? Sure, probably not worth this kind of security. Someone could get credit card numbers, site passwords perhaps, and possibly enough personal information to do some identity theft scheme... Damaging stuff, potentially, but probably not worth their while to extract the data, or worth my while to protect it.
But let's say it contained some sensitive, valuable information from my job - so that stealing my laptop could be a worthwhile target for corporate espionage. Then it might be worth protecting it a little more carefully...

Another thing to consider is that, while the XKCD password cracking algorithm does trump most forms of security, that's only true if someone is actually willing to use it. I could see kidnapping and torture as a real possibility if you were dealing with organized crime or an intelligence agency... Otherwise, the escalation of the crime (from simple theft of a moderately expensive piece of hardware to various forms of felony) would deter most people from attempting it.

If someone has reason to believe it's worth stealing my laptop for the information on it, simply stealing a laptop would be pretty easy. Nick it when I'm at a hotel or something - talk their way past the cleaning staff to get into the room, game over. If a laptop is stolen, police aren't going to care. The machine is simply gone. As long as the initial theft goes off without a hitch, it's a pretty safe crime, especially if they don't try to sell the machine after stealing it.

There's bound to be some level at which information is worth enough to be worth stealing a laptop, but not worth kidnapping and torturing someone for a password... So locking down the machine from those kinds of attacks isn't totally impractical. It just depends on what's on the machine.

Re: the real enemy? (0)

Anonymous Coward | about 3 years ago | (#37223270)

Bears.

Re: the real enemy? (1)

chill (34294) | about 3 years ago | (#37223348)

Only if you're a Packers or Lions fan.

Re: the real enemy? (1)

INT_QRK (1043164) | about 3 years ago | (#37223362)

No, robots. They steal old people's medicine.

Harmless fun (1)

petes_PoV (912422) | about 3 years ago | (#37223296)

this much effort is excessive

Oh let the guy fantasize that he's Johnny Mnemonic or whatever. It's preferable to playing with guns and pretending he's The Terminator

Re:Harmless fun (1)

Qzukk (229616) | about 3 years ago | (#37223356)

It's preferable to playing with guns and pretending he's The Terminator

As long as he only blows out their kneecaps, they'll live.

Or for even better security... (0)

Anonymous Coward | about 3 years ago | (#37223010)

Power it down, encase it in concrete, and toss it overboard into the Mariana trench.

Re:Or for even better security... (4, Funny)

Anonymous Coward | about 3 years ago | (#37223048)

Doesn't protect you from Murlocs or Aquaman.

Aquaman is out to get you, that's why he has been using his aquatic telepathy to convince you to throw your laptop overboard.

The concrete is to protect it from the pressure.

He's very cunning. You have to be with such a lame power.

Re:Or for even better security... (1)

Anaerin (905998) | about 3 years ago | (#37223066)

You know, for a minute there, I was wondering how a hole filled with tomato sauce would help. Guess I better lern 2 reed betta.

wow (2, Funny)

Anonymous Coward | about 3 years ago | (#37223106)

you must value your pron a whole lot more than i do.

Really? (1)

Anonymous Coward | about 3 years ago | (#37223116)

An attacker could cool the RAM, remove it from the running machine, place it in a second machine and boot from that instead.

Is this the whole "freeze electrons in place" nonsense? I'd love to see a real world example of this actually working.

Sounds like the whole "well if you dont wipe your drive with zeros a hundred times a guy with a tunneling electron microscope could count the off spin of the variant quarks.. blah blah " ie; theoretically possible with infinite funding, but not feasible in real life and only happens on movies.

Re:Really? (0)

Anonymous Coward | about 3 years ago | (#37223204)

Slashdot ran an article on that a while ago, it does work. Not flawlessly, but the concept was simple enough: an inverted can of compressed air was used so that the super cold junk at the bottom was deposited on the chips, which cooled them down considerably (note: this is why the cans warn you about getting frostbite if your skin touches it).

Then the DIMMs were removed from the target machine to another computer that was nearby and read out. I guess that implies a hot-swap (err, "live insertion").

I agree with you however, it just isn't practical to be a useful attack in real life. It's cool, but not something you'd actually use.

Re:Really? (2)

Baloroth (2370816) | about 3 years ago | (#37223264)

I was surprised to read that too, but apparently freezing RAM in liquid nitrogen can retain the data stored in it for up to a week. All RAM modules have some data remanence, apparently [wikipedia.org] , and data can last for a few seconds or even minutes in RAM after power loss at room temperature (which is why the hard reset attack works at all) and longer if the modules are cooled (even without liquid nitrogen). I imagine a can of compressed air held upside down would do the trick in a pinch. I was surprised too, but it makes sense. Data isn't held in some magical electrical suspension, it reflects an actual physical state of matter, even in RAM, and while that state may degrade quickly without power, it won't vanish instantly. Higher temperature increases entropy, so cooling it slows that down.

And while these attacks seem unlikely, it is yet another possible attack vector to get at sensitive information. Attacks on PLCs seemed unlikely too, until Stuxnet came around.

I have seen RAM retention in real life (1)

Anonymous Coward | about 3 years ago | (#37223384)

I once worked with an embedded device that demonstrates that nicely. This device didn't clear its display frame buffer on boot. You could power it down, then turn it back on and even several days later and the initial image on the display was recognizable (there was obvious corruption, but you could certainly tell what had been there before).

Re:Really? (0)

Anonymous Coward | about 3 years ago | (#37223590)

Hows about turning on the RAM test in your POST settings... Sure it takes longer to boot, but it also obliterates the RAM as far as the warm-boot attack is concerned. It would be a good idea for servers with confidential data along with making the burgler alarm trip a reset.. Someone breaks in and doesn't deactivate the alarm in time ... boom, keys are gone.

Re:Really? (1)

Riceballsan (816702) | about 3 years ago | (#37223312)

Nonsense in movies data recovery is usually understated while things like breaking encryption are overstated. Oh my god he's using Adk1221 Encryption, that's CIA grade encryption, but I'm a super genious *tap tap tap* 5 seconds later, Got it!. While data recovery is seemingly imposible, a room of people looking at images on a server, OMG he hacked and deleted the images *images instantly disapear from the open file on the screen.

Re:Really? (0)

Anonymous Coward | about 3 years ago | (#37223370)

RAM works by storing charge in capacitors to represent the data. The discharge rate of capacitor is a function of the electromagnetic permittivity of the dialetric, which is a function of temperature. In other words the colder it gets, the longer the capacitors hold their charge and the longer the data stays in them.

The more you know.

Re:Really? (1)

ksd1337 (1029386) | about 3 years ago | (#37223624)

So, couldn't they just design some system that wipes the RAM if a live removal is detected?

Re:Really? (1)

queazocotal (915608) | about 3 years ago | (#37223972)

Umm - no.
Permittivity of the dielectric is pretty much constant with temperature.
Leakage current through that dielectric is strongly influenced by temperature.

Who needs registers (2)

bstrobl (1805978) | about 3 years ago | (#37223120)

You and your fancy registers, I use a specially trained hamster to push buttons depending on the bits it sees on an LED board. And the hamster only taps the buttons in the correct way if fed the correct combination of grains!

Although I am having my suspicions that the little bugger is selling information to the north korean hamsters...

Hmm.... (0)

Anonymous Coward | about 3 years ago | (#37223148)

Tinfoil hat anyone???

Paranoid much? (0)

Anonymous Coward | about 3 years ago | (#37223202)

The frozen RAM trick is a neat concept and all but, let's get real for a moment. How real is the risk? Have you got anything that anyone wants that badly? If you do, is it really worth that much to you to prevent such a desperado from gaining access?

I've go highly sensitive bank(I work there) data on my laptop. It's very important that I prevent the leakage of that data. So much so that I spent an extra $100 to use a hardware encrypted disk(FDE). The baddies would have to grab it while it's running and unlocked or they've got to freeze the memory etcetera. But those are highly unlikely scenarios and they are simply not worth defending against.

Laptops go missing everyday, even in my own company. But, it's usually lost or stolen at an airport or train station, powered off, in its bag and unusable(at least the existing data is) to the person who finds it because of hardware encrypted FDE disks.

All further paranoia is futile. And, for those that say; 'well, I don't have a hardware encrypted disk.' If you're so worried about this stuff and your data isn't worth $100 to protect it with a hardware encrypted disk, then STFU.

Re:Paranoid much? (2)

MightyMartian (840721) | about 3 years ago | (#37223256)

The only people who I could reasonably see being at risk for this would be people like national leaders, diplomats and other REALLY IMPORTANT PEOPLE. I can't imagine such an attack being used against average people, and beyond that even in the case of REALLY IMPORTANT PEOPLE, it's going to have to be done pretty bloody quickly, and I still question how much data you're going to get out of it in real world conditions.

I'm putting this under "paranoid schizophrenic".

Re:Paranoid much? (1)

Qzukk (229616) | about 3 years ago | (#37223402)

When it comes to security, the question is not "are you paranoid?", it's "are you paranoid enough?". Sure, for most people, the answer is "yes", but this is a useful resource nonetheless.

If I ever end up having to move a file of social security numbers or medical records on a portable device, I'll definitely be referring to this and choosing an appropriate level of paranoia.

Re:Paranoid much? (1)

MightyMartian (840721) | about 3 years ago | (#37223484)

The more sensible thing at that point would be not to store it on any kind of portable computer at all, but rather on an encrypted drive of some kind.

protecting ourselves from fatal distractions (-1)

Anonymous Coward | about 3 years ago | (#37223248)

falling gargoyles? par for the 'course'. as the never ending chosen ones' geonocidal holycost goes on & on, there's likely to be attacks on us from anywhere in the universe, or, from our also unchosen neighbors, according to our uncle sam. bad history repeats until it's corrected, or corrects itself?

disarm. read the teepeeleaks etchings. according to the genuine natives, 'its' happening again. see you there for sure, as there's no where left to run/hide fro several billion of us. millions of babys etc... continue to starve, &/or wait to be killed, in real time, all over the planet, today, now. must be the 'hard times' are preventing anybody from noticing/caring etc.... maybe it's the way our media portrays fear, & armed conflict, as OUR choice of pertinent information, leaving out pretty much everything else. as it was profitsized, to fit the never ending corepirate nazi holycost passover.

for each of the creators' innocents harmed in any way.... you know the rest by now.

Why Windows 7 as honeypot? (1)

Czubaka (132534) | about 3 years ago | (#37223262)

I'd imagine a better honeypot. Just install MoviX with preinstalled Cursed Tape from The Ring. Now, if they steal your laptop, Samara gets them in exactly SEVEN DAYS

Bullshit! (0)

ThurstonMoore (605470) | about 3 years ago | (#37223276)

An attacker could cool the RAM, remove it from
the running machine, place it in a second machine
and boot from that instead.

This is the biggest bunch of bullshit I've ever read. This guy needs slapped.

Re:Bullshit! (1)

Osgeld (1900440) | about 3 years ago | (#37223354)

apparently you can, but honestly at that point why bother, if a portable machine is sitting there running with shit in ram just take the thing

Re:Bullshit! (3, Informative)

TheCarp (96830) | about 3 years ago | (#37223412)

It is a theoretical possibility and has been shown to be possible.

Lets be honest though.... it is just not that likely of an attack. Lets not forget you can't encrypt your initrd... Unless you store your boot partition on a USB key and carry it with you, then it can be modified by an attacker. All he has to do it reboot the machine, install a key logger in the initrd, and get the passphrase the next time you type it in.

That or install one between the keyboard and machine. Hell, can probably do everything he needs from the USB bus. Did they ever fix that USB bus problem where a USB device could get full DMA without any OS help required? Hell the USB device could even be installed inside the laptop so its active and invisible while you use it.

Thats before we even talk about things like, installing a pinhole camera to record your keystrokes....oh or using audio, as its been demonstrated that you can reliably recover typed information from recordings of the typing.

Without physical security there is no security. You can't prevent your hardware from being booby trapped... and there are people out there with entire labs devoted to producing this sort of clandestine equipment. Hell, the FBI is known in some instances to have put a tarp in front of a whole house at night, with a print of the original house on it...just so they could work undetected.

Its all a matter of who wants your data and what they are willing to get it.

-Steve

Re:Bullshit! (2)

Sancho (17056) | about 3 years ago | (#37223532)

Lets not forget you can't encrypt your initrd...

You can compute its hash, though, and fail to boot if the hash has changed. See TrustedGrub.

USB devices don't "get DMA" (2)

Burz (138833) | about 3 years ago | (#37223706)

You are thinking of firewire.

Re:Bullshit! (1)

nospam007 (722110) | about 3 years ago | (#37223414)

Not to mention that protecting laptops from sophisticated attacks is not the problem right now.
Protecting servers from unsophisticated attacks is what we apparently need.

Re:Bullshit! (0)

Anonymous Coward | about 3 years ago | (#37223786)

Also need to not store confidential data on laptops when not nescesary

Re:Bullshit! (2)

kaiser423 (828989) | about 3 years ago | (#37223432)

?

Care to elaborate? It's really not very hard at all to put the RAM in another machine, and boot that machine with a little bootloader/program that just dumps to contents of RAM to a file.

The dude even linked to the tool and the technical explanation: http://www.mcgrewsecurity.com/tools/msramdmp/ [mcgrewsecurity.com]

Re:Bullshit! (1)

Reservoir Penguin (611789) | about 3 years ago | (#37224238)

I must be really behind times, but would not informational in RAM disappear without refresh?

Re:Bullshit! (0)

Anonymous Coward | about 3 years ago | (#37223524)

Cold boot attacks - not too complicated.
http://citp.princeton.edu/memory/

Move the live computer to somewhere where you can work on it, without shutting it down first:
http://www.wiebetech.com/products/HotPlug.php

Crack it open, spray the ram with compressed air, keep it very cold, read the RAM out.

This would work great.

Re:Bullshit! (1)

ksd1337 (1029386) | about 3 years ago | (#37223602)

This guy needs slapped.

Sorry, we're all out! Though, we've got a nice discount on kicked!

Re:Bullshit! (0)

Anonymous Coward | about 3 years ago | (#37223604)

http://citp.princeton.edu/pub/coldboot.pdf

Re:Bullshit! (1)

tlhIngan (30335) | about 3 years ago | (#37223608)

An attacker could cool the RAM, remove it from
the running machine, place it in a second machine
and boot from that instead.

This is the biggest bunch of bullshit I've ever read. This guy needs slapped.

Obviously you don't know modern RAM. DRAM needs to be refreshed a lot, but it is surprisingly stable. The longer data is held static in DRAM, the more likely it'll last between boot sessions.

I've done it to debug an OS - the OS logged to RAM, and when it crashed, I merely powercycled the board and could access the memory buffer in the bootloader. It was plain text, but it wasn't until I powered it off for 10-20 seconds did I start noticing corruption. Cooling the RAM preserves the contents longer, and if you're all prepared, it should only take a few seconds to remove all power, pop the memory out, and pop it into another computer.

It's actually a bit of a problem if you have a RAM disk as sometimes the superblocks would be valid, but the data was corrupted enough that things hung and crashed because they assumed that since the RAM disk mounted, the files are still OK. We had to wipe the RAM to fix it - it happened so damn much.

Re:Bullshit! (0)

Anonymous Coward | about 3 years ago | (#37223790)

It's not bullshit. I've been doing it for decades - I remember actually doing cold boot attacks as a mere hacking child, pulling cartridges and cold booting into RAM dump tools in bootsectors when something pesky was living on the reset vector - and a few years ago it's been publicly demonstrated that some of the old tricks do still work.

It's true that modern DRAM fades much faster than the old stuff (especially SRAM, which really can take hours), but some things don't change. Freezer spray on the RAM - it doesn't take liquid nitrogen - massively increases the remanance. You have minutes, instead of seconds, and you're probably coldbooting to something that is imaging the RAM. Bits fade to 1 quicker than to 0. Individual RAM chip models and runs have specific - pretty consistent - fade properties over time (you can even use these to identify them forensically, to some extent). Even if you don't get every bit, if you're looking for a key, you can probably get some of the bits with a much greater probability than 50%, which can massively accelerate a search.

If you want to be secure, you probably want to be actually writing random data and erasure patterns over whatever RAM you can access on powerdown (ultracapacitors are your friend), reboot, or the case being opened. And just because you're being careful with the key doesn't mean you get a free pass on being equally careful with the plaintext.

While you could theoretically do it on the CPU cache and debug registers as well, that presents some practical challenges: you'd have to use JTAG to get it out without destroying it (which involves you already being inside the case), and with it being RAM that naturally runs very hot and short-lived on an extremely fast cycle time, remanance would be comparatively lightning fast.

You could also have even more fun with audio "squeak" (capacitor) or "keystroke" attacks, potential optical "LED bus modulation" attacks (in a few scenarios), power analysis attacks and any number of other physical side-channel attacks. It's an interesting field, really.

[1] Lest we Remember: Cold boot attacks on encryption keys http://citp.princeton.edu.nyud.net/pub/coldboot.pdf

Re:Bullshit! (1)

MacTO (1161105) | about 3 years ago | (#37223806)

Here's a deep and dark secret about digital electronics: it really analog and subject to the same laws of physics as everything else. The only reason why we call it digital is because of how we treat those analog signals. Voltages between 0 V and 0.8 V may be considered as a 'zero', voltages between 2.8 V and 3.5 V may be considered as 'one'. And, of course you don't have a clean transition between those two states either. The transition is defined by the properties of the materials. The properties of the materials are defined by environmental conditions (e.g. temperature). Cooling the electronics down will change how long the contents of RAM will be preserved. Is it enough of a difference? I don't know. What I will say is that I've seen noticeable differences in the amount of noise in CCD detectors from cooling them down.

Re:Bullshit! (0)

Anonymous Coward | about 3 years ago | (#37223832)

It isn't a "theoretical possibility". It isn't bullshit. Fuck you all. It's been done. I first heard of this in community around 2006 or so. It was referenced after that in papers. A part of me suspects a few elite organizations probably used this as early as 2002.

http://citp.princeton.edu/pub/coldboot.pdf
http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-536.html

There's an early paper--cold boot recovering AES keys from RAM. There's off the shelf software that will do this with windows bitlocker.

Now please, stop talking about things you don't understand children.

Paranoid Much? (1)

paulmac84 (682014) | about 3 years ago | (#37223288)

There's caring about the safety and security of your data, then there's being obsessed about the safety and security of your data, and way over the horizon is this guy.

Re:Paranoid Much? (4, Insightful)

Sancho (17056) | about 3 years ago | (#37223382)

Think of it like a hobby. It may not be really practical, but it's interesting to some people.

Re:Paranoid Much? (1)

TheCarp (96830) | about 3 years ago | (#37223456)

There is also just being interested and wondering if you can do it. There is also the possibility of doing it because someone large like a major national government's thugs (china, US, etc) want your data, or the data of the people you are developing the procedures to help.

of course, if thats the case, then.... this is perhaps not over the horizon at all, they are, in fact, inadequate protections.

Course, nothing will protect you from the "$5 wrench" scenario (not that any government would ever pay that little for a wrench).

Laptops (1)

Osgeld (1900440) | about 3 years ago | (#37223300)

its like putting your life savings in your wallet.

Re:Laptops (1)

gknoy (899301) | about 3 years ago | (#37223580)

Especially if you use Bitcoin.;)

A lot of work for little gain (2)

BitZtream (692029) | about 3 years ago | (#37223380)

TRESOR is an implementation of AES as a cipher kernel module which stores the keys in the CPU debug registers, and which handles all of the crypto operations directly on the CPU, in a way which prevents the key from ever entering RAM.

Awesome, its stores the keys in the cpu debug registers when in use. The data to recreate them still has to flow into the CPU from ram, so all you're taking out is the path between ram and the CPU for an intermediate step. So all you get is a speed boost, no security gain since the attacker already knows the algorithm your using and all the data you provided to the CPU. The speed boost is nice if its being used all over the place (like for an encrypted FS) but otherwise its not that big of a deal and its certainly not new.

As for the rest, cryptfs or bitlocker with your screensaver/lock setup to throw out your keys when the screen blanks/suspends/whatever.

So basically Win7 with BitLocker enabled or whatever alternative setup results in the same thing on Linux. Its not even a little hard, and you've already got well past the point where they'll just beat the password out of you.

If you did it to learn, good for you. If you did it for some sort of practical value, then this really is one place where epic fail applies.

You are an idiot. (0)

Anonymous Coward | about 3 years ago | (#37223538)

If the AES keys never touch the RAM, then whatever is on the RAM is useless to anyone who does not have the keys.

Re:A lot of work for little gain (1)

Sancho (17056) | about 3 years ago | (#37223550)

I believe the idea is to load the keys into the debug registers, and then erase the keys from memory. Then cold-boot attacks won't work.

Yes, the keys do go into RAM, but you significantly reduce the amount of time that they are there. Normally, keys are in RAM as long as there is a mounted cryptfs.

Re:A lot of work for little gain (1)

Anonymous Coward | about 3 years ago | (#37223584)

As for the rest, cryptfs or bitlocker with your screensaver/lock setup to throw out your keys when the screen blanks/suspends/whatever.

eCryptfs (deployed on Ubuntu Linux and RHEL) will not throw out your keys on suspend and hibernate, but BitLocker will. BitLocker will not throw out your keys when your screen locks. Think about it; there are still running processes that need to access the disk while the screen is locked.

That said, if you care about usable and secure full disk encryption, your best bet today is to run Windows 7 Ultimate and enable BitLocker with a TPM+PIN protector.

Re:A lot of work for little gain (2)

linuxrocks123 (905424) | about 3 years ago | (#37224316)

The security gain comes from the fact that it is feasible to perform a side-channel attack on RAM but infeasible to perform a side-channel attack on CPU registers. The data to recreate the keys is scrubbed from RAM; the keys never leave RAM. I have done work on a similar project to TRESOR, called Loop-Amnesia [livejournal.com] , which uses MSRs instead of the debug registers to perform the same task and does not require AES-NI support.

---linuxrocks123

non removable memory (1)

magarity (164372) | about 3 years ago | (#37223444)

An attacker could cool the RAM, remove it from the running machine, place it in a second machine and boot from that instead
 
Half of my netbook's memory isn't removable and if the author is actually worried about this kind of thing he can get a similar model and bite the bullet on performance by operating it with only the internal ram. I doubt the residual charge would last through unsoldering the chips and attaching them to a board to be put in another machine.

Re:non removable memory (2)

sp0tter (1456139) | about 3 years ago | (#37224106)

or one could superglue the DIMMS in place

Sounds like a TPM chilp could help you (1)

fx242 (1222592) | about 3 years ago | (#37223526)

... as the root keys never leave the chip. But hey, trusted computing is eevil right?

Re:Sounds like a TPM chilp could help you (1)

Reelin (2447528) | about 3 years ago | (#37224158)

No, trusted computing is useful. What corporations are trying to do with it is eevil...

this begs the question (1, Insightful)

pak9rabid (1011935) | about 3 years ago | (#37223572)

What does he have on his laptop that's so gd important that he has to go through this much hassle to secure it....kiddie porn?

Re:this begs the question (-1)

Anonymous Coward | about 3 years ago | (#37223828)

No, mother fucker, it _raises_ the question.

Re:this begs the question (2)

MacTO (1161105) | about 3 years ago | (#37223838)

Worse. Photos of kittens playing with balls of yarn! Something that he can't let his colleagues see lest he be shamed for the rest of his life.

Re:this begs the question (0)

Anonymous Coward | about 3 years ago | (#37224056)

I agree, anybody who attempts to secure their computer beyond setting a root password is almost certainly a paedophile.

Re:this begs the question (1)

rocket rancher (447670) | about 3 years ago | (#37224276)

What does he have on his laptop that's so gd important that he has to go through this much hassle to secure it....kiddie porn?

Security does not imply criminality. Go fuck up some other thread, you asswipe troll.

Solving the wrong problem (1)

cloudmaster (10662) | about 3 years ago | (#37223642)

If your laptop is valuable enough that someone would go through the effort of chilling the RAM and booting the machine, you should probably not be laying your laptop out on the table at Starbucks. In fact, if your laptop is that valuable, you've done something incredibly stupid in your systems design.

Encrypt the data (either individual files, your homedir, or the whole drive), and don't use a really stupid password. If that's not good enough for your data, then your data belongs on a system which is not portable and which has actual physical security applied.

Re:Solving the wrong problem (1)

cloudmaster (10662) | about 3 years ago | (#37223666)

Err, booting it in a different machine. Though I suppose one can imagine a criminal saying "Aww man, it's turned off. Well, off to find an easier target!". :)

Re:Solving the wrong problem (0)

Anonymous Coward | about 3 years ago | (#37223930)

OK, Often I need to upload the config file to a router in a bank branch that is out of cell phone range... How would you suggest I do that without having the data on my laptop? The router is down, so uploading it to the bank branch sever is not an option. There is no wifi in range, nor cellphone/3g coverage. The bank uses VoIP phones which also depend on the router.

Re:Solving the wrong problem (0)

Anonymous Coward | about 3 years ago | (#37224244)

You store the data on a microSD card, hide that in your belly button, then use a laptop with nothing valuable on it to upload the file.

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