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New Anti-Forensics Tools Thwart Police

rabblerouzer writes "Antiforensic tools have slid down the technical food chain, from Unix to Windows, from something only elite users could master to something nontechnical users can operate. 'Five years ago, you could count on one hand the number of people who could do a lot of these things,' says one investigator. 'Now it's hobby level.' Take, for example, TimeStomp. Forensic investigators poring over compromised systems where Timestomp was used often find files that were created 10 years from now, accessed two years ago and never modified."

16 of 528 comments (clear)

  1. Time Stamps? by iminplaya · · Score: 5, Funny

    Simple! Just cut the disk open and count the rings.

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    What?
    1. Re:Time Stamps? by iminplaya · · Score: 5, Funny

      Yes, and notice how I modified the time stamp AND the comment number to make appear the parent is the first post.

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      What?
  2. Pfft. by RealGrouchy · · Score: 5, Funny

    This has got to be old news. Over 112% of Slashdotters have been using these programs for years, since at least 3 months from now!

    - RG>

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    Hey pal, this isn't a pleasantforest, so don't waste my time with pleasantries!
    1. Re:Pfft. by trolltalk.com · · Score: 5, Funny
      Gee, and I thought it was a free "feature" included with every version of Windows and DOS.

      FILE0001.CHK
      FILE0002.CHK
      FILE0003.CHK
      FILE0004.CHK
      FILE0005.CHK
      ...
      FILE9999.CHK
      Unable to find COMMAND.COM. Please insert system disk and press reset.

    2. Re:Pfft. by andy_t_roo · · Score: 5, Interesting

      actually, that's a bit extreme, all you need to do is to heat it above the curie temperature (300-380 for Fe-Nd alloys) at this point the magnetic properties become completely dependent on the applied magnetic field, so as it cools down again, the only magnetization left is due to the earths magnetic field. Below this temperature you need to apply a strong magnetic field to reverse *most* of the magnetization (thats how normal recording works). As an added bonus if you do this in such a way as there are not dust contaminants (inductive heating of the platters in a vacuum) you still have a working drive.

    3. Re:Pfft. by Daniel+Dvorkin · · Score: 5, Interesting

      When I suffered a bizarrely bad disk crash (i.e., it crashed in an odd way that was much more destructive, and made the data much harder to recover, than most crashes; I've forgotten most of the details, but I remember that) a few years ago, I took my disk to a recovery specialist that does, among other things, contract work for the FBI. I got a brief glimpse inside their clean room. They had disks that had been pounded with hammers, run over with trucks, immersed in salt water ... you name it, these guys could get data off it.

      --
      The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
    4. Re:Pfft. by plover · · Score: 5, Insightful
      At work the standard we gave our service vendor for destroying failed drives involved a drill press and epoxy. We're concerned about data thieves, not Three Letter Agencies.

      For my personal drives at home, I just use a three pound hammer. A scraped, smashed and warped platter hitting the trash bin is effectively unreadable, and all I'm really concerned about is a bad guy finding bank account information. If someone official really wanted a working drive of mine, pajama-clad ninjas would probably come for it in the middle of the day while I was at work anyway.

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      John
  3. Macs... by Wizard+Drongo · · Score: 5, Interesting

    Hate to sound like a apple fanboi, but even for those with something to hide that don't know much about computers at all, and therefore lack the know-how required to use these tools, simply using Mac OS X and turning on File-Vault, sad as it sounds, is enough to confound the majority of law enforcement. Most of the contractors that the police in the UK use are windows only. I know for fact that any linux or 'specialist' computers get passed to a specialist data firm in Germany for decoding...
    Macs?
    Only in the most serious of cases are macs in the UK sent for hacking if File-Vault's on. They go to Canada and take upwards of a year to crack. If ever.
    Unless you've done something pretty fucking serious, and the police know the evidence is on the machine, just can't prove it, they usually won't go to the expense.
    Of course, only the most stupid and inept of morons would be doing illegal shit and storing it on their computer without using the most powerful encryption possible, and only storing that which absolutely must be stored. Mind you, criminals are not usually noted for their cunning and intelligence....

    It goes without saying that the above does not translate to across the pond, nor does it apply on Security operations with terrorists and the like. How MI5 & MI6 do things is completely different and tends to involve some 'specialist' people from the likes of the I-corps and in-house solutions....
    I could elaborate, but I'm not THAT dumb.....

    --
    The truth shall always be free: Boris Floricic is Tron.
  4. oh geez... the "police" by porkThreeWays · · Score: 5, Interesting

    Let me let everyone in on a dirty little secret about 99% of police computer forensics experts... they are less skilled than most 9 year olds at recovering vital information. Many of them use bootable disks that just check the hard drive for IE's cached files and history, etc, etc. Simple stuff a child could do. These people aren't doing complex low level block analysis. They are doing the level of recovery parents do at the end of the night to see what websites their children went on. Does it surprise anyone then it's extremely easy to fool them? God forbid you use encryption, an OS they aren't familiar with, or hardware they've never seen. They'll never recover anything.

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    If an officer ever threatens to taze you, say you have a pacemaker.
  5. Re:A year ago... by Profane+MuthaFucka · · Score: 5, Funny

    Don't knock it. Catching cheating spouses is a great way to get laid. You've already established that they've got no problem sleeping with people other than their husbands, which is 90% of the battle usually.

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  6. Re:Here's a real good one by Anonymous Coward · · Score: 5, Insightful

    You'd have to be careful about the choice of encryption algorithms when you do this. There are good reasons (which I can't cite off the top of my head; I'm no cryptographer) why triple DES, for example, has an encrypt-decrypt-encrypt pattern, rather than encrypt-encrypt-encrypt. Even then, all you achieve is a doubling of the effective key length, not a tripling (and remember that the actual key is three times as long - each step uses a different key).

    Cryptography is hard. I know enough to know that I know nothing about it, and that I'd screw the pooch on any crypto system I might implement. If you haven't a very solid maths background, and a lot of experience breaking cyphers (and I'm talking about more than just the simple Julius shift here), odds are extremely high that there's a flaw you've overlooked in your system.

  7. Epically bad. by rjh · · Score: 5, Insightful

    I am an NSF–funded researcher in computer security, focusing on electronic voting. Data privacy and confidentiality is very important to us, as you can imagine.

    Your idea is quite terrible.

    First, what do you mean by a file "without signature"? Take a zip archive as an example--even if you strip off the zip header, any forensicist worth his or her salt can figure out it's a zip archive, just because of the way the data is structured. Encrypted filesystems have structure, too. A data forensicist can recognize an encrypted container on the basis of its structure. (Some people have recommended to you TrueCrypt in hidden volume mode. This is bogus. I'll explain that if you want.)

    Second, you appear to not understand how crypto works. Two layers are better than one, right? So double ROT13 encryption is stronger than single ROT13, right? You're running smack into a major, well-known area of crypto. A lot of ciphers do not composite themselves well. You are almost always better off just picking one algorithm with a strong keysize than a composition of multiple algorithms.

    Third, how do you plan on managing all of your keys? Key management is a thorny enough problem in the best of times. By relying on multiple keys you're multiplying the problem immensely.

    You really need to do some basic research in crypto.

    1. Re:Epically bad. by rjh · · Score: 5, Interesting

      Why do you think hidden-volume mode TrueCrypt is bogus?
      Let's imagine that you've got a TrueCrypt container on your hard drive. The FBI gets a tip that you're involved in child porn. You get arrested. The DA has a jailhouse snitch who'll testify that you have kiddie porn. The DA has a forensicist who will testify that you've got an encrypted container on your disk drive. You don't want to be doing 10-to-25 in federal pound-me-in-the-ass prison, because you're a scrawny pimply-faced geek and you don't want to get married off to the biker with the most cigarettes. You tell the DA "... look, okay, here's the passphrase to my TrueCrypt container. See? There's just porn in there I was hiding from my wife! But everyone involved is over 18! Let me go! It's bogus!"

      The DA just smiles at you and says... "I'd like to see the hidden container inside that TrueCrypt volume. My forensicist says oftentimes people do that with TrueCrypt."

      You say "umm... there isn't a hidden container... there's nothing more there..."

      The DA continues to smile. "Prove it to me."

      You say "umm... I can't... that's exactly what TrueCrypt means when they say it's hidden... you can't prove it exists and you can't prove it doesn't exist..."

      The DA rises from the table. "Say hi to your husband for me when you meet him."

      Moral of the story: it is very, very important that you be able to prove the existence or nonexistence of your data.

      Can you explain more of this please?
      I don't know how to make it any simpler. If compositing encryption functions makes things harder to break, we'd expect two applications of ROT13 to be stronger than one application of ROT13. It doesn't work that way. And in an exactly similar way, two levels of AES may or may not be any better than a single layer of AES. Or one layer of Blowfish and one layer of 3DES. Or...

      If you want to get more sophisticated than this, you need to take a collegiate math course focusing on group theory.
    2. Re:Epically bad. by Anonymous Coward · · Score: 5, Informative

      I'm not an NSA funded security researcher, but I'm also slightly less of an arrogant prick than "rjh". So to answer your question about layering encryption without getting into all the you're-not-even-worthy-to-be-asking-this-question crap, here's a brief layperson's answer:

      Essentially your idea is not a bad one, it's just a bit naive -- there are non-obvious subtleties which must be considered in order to make the idea work as well as you hope.

      One issue is that some encryption algorithms (called "groups") have the characteristic that when applied two consecutive times with different keys, the result is the same as if the algorithm was applied only once with some other third key. If this is the case for your favorite algorithm, then your plan adds no extra security compared to just encrypting once. And apparently it's not always easy to know whether this is the case for a complex algorithm, so you should assume the worst.

      Another issue is that if your adversary can guess some plaintext (e.g. by assuming it contains .doc or .jpg headers) they can use a technique that trades off storage for computation and break your multiple encryption much faster than you would have thought.

      One way to overcome these weaknesses is by applying your encryption in "EDE" (encrypt-decrypt-encrypt) mode, where you encrypt with one password, then "decrypt" with a second password (which is obviously not really decrypting but just making the scrambling that much more horrendous), and then encrypting again with a third password. Even this is not as secure as you might expect, but it's still pretty good.

      The well-known security and crypto expert Bruce Schneier has a great book called "Applied Cryptography" (Wiley, 2nd edition 1996, ISBN 0-471-11709-9) which is accessible to average smart, interested, non-NSA-funded Slashdot readers without advanced math degrees. It even has a brief chapter (15) on this exact topic. (Schneier has other great books too.)

      Despite his attitude, "rjh" is right in implying that our common sense is not trustworthy in the area of cryptography -- some of the world's smartest people devote their lives to this stuff and have come up with astonishing and often counterintuitive results. Smarter people than us have already studied this idea, which is basically a good one even though it has pitfalls. Don't let anyone make you make you feel stupid for having an idea or asking a good question.

    3. Re:Epically bad. by davFr · · Score: 5, Interesting

      I don't know how to make it any simpler. If compositing encryption functions makes things harder to break, we'd expect two applications of ROT13 to be stronger than one application of ROT13.
      It is a cryptanalysis problem. Encryption scheme are designed so that your clear text will become close-to-random garbage when encrypted. Why? Because if it is not random, forensics can do statistical analysis on the crypted data 1/ to identify the encryption algorithm, 2/ to try to guess the encryption key (http://en.wikipedia.org/wiki/Cryptanalysis/ for more details).

      If you crypt your text twice (or more) you modify the entropy of the encryption scheme, and the encrypted data will be not optimally close to random data. As a conclusion, encrypting twice made your data less robust to forensics.
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  8. Re:Here's a real good one by RyuuzakiTetsuya · · Score: 5, Funny

    just do some petty theft on top of that and overflow it back to 0x01.

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    Non impediti ratione cogitationus.