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Broken CD Project

glenn126a
(@glenn126a)
New Member

Hey all,

I request some help in tackling this project that i have for computer forensics class.

I have to recover data from a broken CD that has been broken into four pieces. The data that I am trying to recover is a simple .txt file that was created by my partner. The CD contains only that .txt file. Any idea as to where I should start?

Quote
Topic starter Posted : 16/11/2011 8:19 pm
markg43
(@markg43)
Member

I make no promises and unfortunately, this is going to be like physical forensics. You MAY destroy the evidence in the attempt to retrieve. Perform at your own risk.

First off, you have to fix the CD. Couple ways to try - get one of the CD blanks from a stack of new disks. You know, the one see through plastic CD thingys that you see on the top and bottom of the stack. Then get some glue - preferably spray on so you get a thin even coat. Now try to mount the broken CD onto the blank (glue the blank onto the top of the broken CD). Alignment will be crucial - use a microscope or something. Helps if the glue is slow setting so you can move the broken one around for a bit.

The other way to mount it is to get a sheet of sticky laminate, the clear stuff you put over paper. This is less forgiving because it will set as soon as you stick it.

Those are my ideas for fixing the CD.
———————

Data recovery - get as OLD a CD drive as you can. The slower the better. I have heard that very old SCSI CD drives - circa early-mid 1990s are good. The guys at Infinadyne (the CD recovery experts) recommend Plextor 12-10-32 and 12-4-32 CD-RW (though these are not as old as SCSI, but easier to obtain).

See if CD/DVD inspector has a trial license. You might even email the company (it is a Mom & Pop shop - literally) and see if they have ideas.

Finally - read everything you can at this site http//www.infinadyne.com/forensicsoftware.html

Good luck. I would have been nicer if the disc had not been broken fully apart.

ReplyQuote
Posted : 16/11/2011 9:13 pm
mscotgrove
(@mscotgrove)
Senior Member

I think the chances are very very slight. Despite several special techniques I use, I have never managed to read a cracked CD.

Let us know if you succeed, and good luck.

ReplyQuote
Posted : 16/11/2011 9:28 pm
armresl
(@armresl)
Community Legend

This is a frequent question in forensic classes and while I can't tell you where specifically to look, there is an answer on how to accomplish this task.

ReplyQuote
Posted : 16/11/2011 10:08 pm
markg43
(@markg43)
Member

Armresl - That's a bit of a cryptic answer. Do you have a hint?

ReplyQuote
Posted : 16/11/2011 11:49 pm
mscotgrove
(@mscotgrove)
Senior Member

Reading the question again, I think I would start with the PC that burnt the CD.

You know who burnt the CD, and therefore probably which PC.

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Posted : 17/11/2011 12:01 am
jaclaz
(@jaclaz)
Community Legend

Hmmm.

My advice would be to not even THINK of using a "normal" CD drive with a "cracked" CD (let alone one that has been broken into pieces and sticked together).
You will need a very old one, possibly 1x in speed but more than that, a model with a caddy (to minimize risks of having pieces of the CD going everywhere) AND it will also need to be modified to allow reading an IDENTICAL (blank or written) CD media (which may difficult or impossible to find) and to swap it without notifying the media change.
Will it work (to retrieve a single - I presume smallish - .txt file) ?
Quick answer
No. (
Even IF the setup works, AND the CD doesn't break again as soon as it is spinned up, chances of getting that .txt file are pretty much low, I guess we could feed them to the Heart of Gold
http//hitchhikers.wikia.com/wiki/Heart_of_Gold
Improbability Drive
http//hitchhikers.wikia.com/wiki/Infinite_Improbability_Drive
and have it get you on the other side of the universe pretty fast without even needing a hot cup of tea….

jaclaz

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Posted : 17/11/2011 1:22 am
Passmark
(@passmark)
Active Member

Maybe run the disk under a microscope, note down the pits on the disc, convert to 1's and 0's and you're done. -)
http//ece.wpi.edu/~hammouri/CD/

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Posted : 17/11/2011 3:41 am
nlpd120
(@nlpd120)
Member

I like the suggestion of the microscope, however, maybe use it to line up the substrates and use a CD label to help hold the pieces together. and use a very low speed cd drive i.e. 1x, 10x, etc… The CD label alone didn't work for me, so the microscope may come in handy here.

Regards,

Chris

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Posted : 17/11/2011 7:42 am
jaclaz
(@jaclaz)
Community Legend

Maybe run the disk under a microscope, note down the pits on the disc, convert to 1's and 0's and you're done. -)
http//ece.wpi.edu/~hammouri/CD/

Just for the record in the given link the experiment makes NO use whatsoever of a microscope, it simply shows a picture taken with an electron microscope to illustrate how the pits look.

IMHO to read a broken CD you will need something far more complex than a "common" CD reader.

And no a microscope won't be of any use if not to very carefully remove an infinitely small quantity of material from the cracked edges so that you can actually "reassemble" the Cd "properly" (as in the cracking process the material around the edge will have bent and pieces will simply NOT fit together "as is" ) and to re-align the pieces accurately.

The CD should be enclosed in *something* that keeps the assembled pieces "round" and "balanced" and "in a plan" with a precision of tens )or maybe hundredths) of a mm.
Ideally something like a "mould" with a very thin (and transparent) lid.

"Reinforcing" the disc on one side only cannot possibly work, and definitely a CD label won't do, you will need something as rigid as the original CD was.

Possibly another CD glued on the "label" side might do. (but then you will need to further modify the reader to allow for this "double" thickness).

jaclaz

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Posted : 17/11/2011 5:17 pm
SFGAirborne
(@sfgairborne)
New Member

I'd guess that you're over-thinking it, and working far too hard. Find the machine the CD was burned from.

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Posted : 17/11/2011 5:25 pm
jaclaz
(@jaclaz)
Community Legend

I'd guess that you're over-thinking it, and working far too hard. Find the machine the CD was burned from.

Or kidnap your "partner" and have him/her re-type the short .txt message under menace or simply extort him/her a copy of it…..

jaclaz

ReplyQuote
Posted : 17/11/2011 5:46 pm
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