Do LCD monitors save images to system memory

[Starbuck1975]

So I overheard some of the contractors in our office that install LCDs, periperals and desktop computers at our workstations.

In our office, they rotate the LCDs out fairly frequently, and I asked the contractor what happens to the old LCDs once they are replaced.

I think he was assuming some things, but he said that they have to go through a refurb process for security reasons.

I asked what security reasons?

He said that it is possible to take an LCD screen and extract what the previous owner had brought up on his screen. I kind of questioned it, but then again, since every component these days seems to have its own memory, I couldn't call him on it.

So if someone were to take my work desktop monitor, and hook it up to another computer, could they extract the last images I was viewing on my screen?

 

[alaricljs]

That's a flying barrel of monkeys flinging poo.

 

[TanisHalfElven]

Originally posted by: alaricljs
That's a flying barrel of monkeys flinging poo.

QFT

 

[superbooga]

Originally posted by: alaricljs
That's a flying barrel of monkeys flinging poo.

How do you know?

You can still recover data even if a hard disk has been formatted and every bit set to zero.

You can recover an image from LCD screen, by reading from the memory cells the LCD controller uses.

Volatile memory isn't as volatile as you think, if you shut off your computer and attempt to read from RAM an hour later, you'll find most of the data is still there.

And even without memory, you could probably recover the image from the orientation of the liquid crystals.

 

[theprodigalrebel]

Unpossible.

 

[superbooga]

Here's some simple information regarding deletion of data. You have to realize that even if the software doesn't see previous data, physical evidence is left behind.

http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html

 

[alaricljs]

OK, Do you unplug your monitor instead of shutting it off? Do you not use the shutdown sequence of windows which includes a completely different image than the last one you looked at?

They MIGHT be able to recover the very last frame displayed on the screen... That frame has never once contained anything of any use to anyone at all that I've ever seen.

 

[SunnyD]

Originally posted by: superbooga
Here's some simple information regarding deletion of data. You have to realize that even if the software doesn't see previous data, physical evidence is left behind.

http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html

You do realize that that article does refer to long-term memory (magnetic and SOLID-STATE memories) right?

Standard DRAM will NOT retain memory for your supposed 1-hour if all power has been removed from it. In fact, it will not retain memory after the rated discharge of the capacitor in a DRAM cell. When you go to read an unpowered DRAM cell, you will get a random state 1 or 0 on each bit due to whatever its designed power on state is, the magnetic fields around it, the position of the earth relative to the sun, the value of pi to the thirteen-quadrillionth decimal place, etc... it's random.

Now if you're talking about DRAM in a computer that is shut off but not devoid of any electrical source (ie: still plugged in/on battery), that's a completely different story all together.

Also, the proper way to secure a hard drive is to consistantly write cycle it about a dozen times with all 1-bits, then all 0-bits after doing a full magnetic wipe of the drive.

 

[MercenaryForHire]

Originally posted by: superbooga
a whole assload of blatantly incorrect information from two separate posts goes here

I'm going to have to start billing for the ammo I use strafing threads with the ROFLCopter. :laugh:

- M4H

 

[xtknight]

Certainly not in any reliable manner. The cells of liquid crystals do on occasion get stuck (burn-in) but to except to actually retrieve anything usable from them is ridiculous unless it's done within a short period of time (maybe 2 days). It's vaguely possible that you could show a bright, big credit card number on an LCD and leave it there for 5 hours and then come back and be able to see it later. Is anyone that stupid? I doubt it.

 

[zephyrprime]

Originally posted by: superbooga

Originally posted by: alaricljs
That's a flying barrel of monkeys flinging poo.

How do you know?

You can still recover data even if a hard disk has been formatted and every bit set to zero.

You can recover an image from LCD screen, by reading from the memory cells the LCD controller uses.

Volatile memory isn't as volatile as you think, if you shut off your computer and attempt to read from RAM an hour later, you'll find most of the data is still there.

And even without memory, you could probably recover the image from the orientation of the liquid crystals.

Memory in a capacitor can last a long time but dram cannot last nearly 1 hour. The refresh rate on ~10 microseconds and if power were cut, data couldn't last a whole lot longer.

I wonder though, if it isn't possible to have a slight memory on the lcd pixels's electronics due to the floating body effect. In any event, it would be too weak to read and the contractors are talking total BS.

 

[Acanthus]

Originally posted by: zephyrprime

Originally posted by: superbooga

Originally posted by: alaricljs
That's a flying barrel of monkeys flinging poo.

How do you know?

You can still recover data even if a hard disk has been formatted and every bit set to zero.

You can recover an image from LCD screen, by reading from the memory cells the LCD controller uses.

Volatile memory isn't as volatile as you think, if you shut off your computer and attempt to read from RAM an hour later, you'll find most of the data is still there.

And even without memory, you could probably recover the image from the orientation of the liquid crystals.

Memory in a capacitor can last a long time but dram cannot last nearly 1 hour. The refresh rate on ~10 microseconds and if power were cut, data couldn't last a whole lot longer.

I wonder though, if it isn't possible to have a slight memory on the lcd pixels's electronics due to the floating body effect. In any event, it would be too weak to read and the contractors are talking total BS.

Its simply not possible, even if that were the case, youd only be able to pull up last thing displayed, which unless the people working on it are REALLY retarded, will be the windows shutdown screen.

 

[superbooga]

 

[aka1nas]

Sounds like your contractor has a really sweet gig. He gets free LCDs all the time because your company is gullible. I should mention this one to my boss next time he goes onsite.