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Forensic Discovery

Posted by timothy on Tue Jan 18, 2005 06:10 PM
from the big-fat-y-incision dept.
Books Media Security Book Reviews
Ben Rothke writes "When most people think of forensics, television shows like Quincy and CSI come to mind. Where such shows deviate from reality is the unrealistic speed at which the actors are able to identify, apprehend and prosecute the perpetrators. In the real world, (unlike television, where the crime must be solved by the end of the family hour), crimes are solved with slow, deliberate and methodical steps. The prodigious incidence of digital crime has elevated computer forensics to a critical role within the field of information security. The focus of computer forensics is twofold: first is the attempt to determine whether a breach has occurred and to stop the perpetrator; second is prosecution of the offender, if the breach was a criminal activity." Read on for Rothke's review of Forensic Discovery.

Security luminaries Dan Farmer and Wietse Venema wrote one of the first vulnerability scanners (SATAN) almost 10 years ago; SATAN was the precursor to ISS Scanner, Retina and nmap. Venema wrote such well-known security applications as the TCP Wrapper program and the Postfix mail server. Farmer and Venema's new book Forensic Discovery is a valuable book that grounds a computer-savvy reader in the world of digital forensics.

An image of a pipe by artist René Magritte is on the cover with the caption Ceci nest pas une pipe. ("This is not a Pipe.") The picture demonstrates that an object exists on many planes; the simple recognition of the picture initiates the belief that we are seeing something, but it is only known in representation. Surrealist painting and digital forensics coalesce in that the digital forensic investigator must think broadly and unconventionally in order to reconstruct an incident, all the time keeping in mind that often what initially seems obvious is neither real nor correct.

The material in the book is an outgrowth of a one-time seminar the authors gave in 1999 on digital forensics and analysis. At the seminar, Farmer and Venema rolled out The Coroner's Toolkit (TCT), a collection of tools for gathering and analyzing forensic data on a Unix system. TCT is heavily referenced throughout the book.

The book initially seems thin, at just 198 pages, but there is no filler and the information is presented in a fast and furious manner. Part one of the book comprises 35 pages and is an introduction to the foundations of digital forensics and what to look for in an digital investigation.

Part two (chapters 3-6) is the nucleus of the book, which quickly gets into low-level details about file systems and operating system environments. While other forensics books focus exclusively on the discovery and gathering of data; Forensic Discovery adds needed insight on how to judge the trustworthiness of the observation and the data itself. Again, the idea is that not everything is as obvious as it may initially seem. An effective investigation often requires intense analysis, where meaningful conclusions take time.

Chapter 4, "File System Analysis," notes that while computers have significantly evolved since their inception, little has changed in last 30 years in the way that file systems actually handle data.

Chapter 5, "Systems and Subversion," is particularly interesting as it deals with system startup and shutdown, from a forensics perspective. The chapter shows that there are thousands of possible opportunities to subvert the integrity of a system without directly changing a file during startup and shutdown. A crucial decision that must be made during an incident is whether to shut down the system or let it remain on-line. There are advantages and disadvantages to each approach, and the book details them.

Part three (chapters 7-8) is about the persistence of deleted file information. The authors' research reveals that data can be quite resistant to destruction. The book shows that a huge amount of data and metadata can survive intended deletion as well as accidental damage.

Forensic Discovery is unusual in that other books on forensics are often nothing more than checklists and step-by-step instructions on what to do during an incident. Forensic Discovery provides a broad framework on the nature of data and how it can be recovered for forensic purposes. By understanding the underlying operating system, the act of analyzing and dealing with a security breach becomes much easier.

The book's target reader is anyone who wants to deepen his understanding of how computer systems work, as well as anyone who is likely to become involved with the technical aspects of computer intrusion or system analysis. The topics are too advanced, to make it the right book for the novice system administrator. For the technical reader, though, Forensic Discovery is one of the best computer security books published in the last year. The value of the information is immense, and the extensive experience that the authors bring is unmatched.

You can purchase Forensic Discovery from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
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  • huh!? (Score:4, Funny)

    by Turn-X Alphonse (789240) on Tuesday January 18 2005, @06:14PM (#11402379) Journal
    So crimes arn't solved by old ladies finding a lipstick, some shoes and avoiding being shot!? Thats it! I'm never donating to "Help the aged" again!

  • Nice going... (Score:4, Funny)

    by lightspawn (155347) on Tuesday January 18 2005, @06:16PM (#11402401) Homepage
    Where such shows deviate from reality is the unrealistic speed at which the actors are able to identify, apprehend and prosecute the perpetrators. In the real world, (unlike television, where the crime must be solved by the end of the family hour), crimes are solved with slow, deliberate and methodical steps.

    Great. Now the criminals know they probably won't be caught. Good job!

  • Quincy!?! (Score:4, Funny)

    by FuturePastNow (836765) on Tuesday January 18 2005, @06:17PM (#11402417)
    Quincy, M.E.? I was two years old* when that show went off the air. Raise yor hands, Slashdotters, how many of you think of Quincy when you think of forensics?

    *http://us.imdb.com/title/tt0074042/ [imdb.com]

  • Computer forensics (Score:5, Interesting)

    by Anonymous Coward on Tuesday January 18 2005, @06:24PM (#11402471)

    I met a young, single woman who did computer forensics for the police. She told me over dinner that while she thought her work was important, it caused her a lot of stress in her life. She said there were many times where she recovered images from the computer of a sex criminal that were really indiscribable.

    She was really good looking and had a body that you normally don't find on a girl geek. But, man, I wasn't about to start dating some chick who comes home from work sobbing from prowling through gigabyes to violent sexual jpegs and avis. I guess that's why someone so damn good looking and smart was still single...

    • Re:Computer forensics (Score:4, Funny)

      by djward (251728) on Tuesday January 18 2005, @06:32PM (#11402559)
      Sounds like she needs some consoling. And I think I know just the man for the job.

      You still got her number?

      • In all seriousness... (Score:5, Interesting)

        by Anonymous Coward on Tuesday January 18 2005, @06:51PM (#11402719)

        Sounds like she needs some consoling.

        Well, it was that "some" in "some consoling" that I wasn't sure about. How much? She's telling me on the first date that she's under tremendous stress. I appreciate her honesty and respect her for that but I suspect that if she feels the need to divulge that on a first date, the level of consoling is likely to be more than "some". That's what I was worried about. To be dating a girl with a face and a body like that who knows her way around computers like a pro and who is doing a job that is clearly a service to mankind sounds like a geek's wildest dreams come true. But therein lies the problem: this is the kind of girl who most of us would fall head-over-heels for. I was afraid of getting really wrapped up in her and then having to endure of heartache of having her crying in my arms once a week or more. Or having her push me away in bed because she had seen something at work that had turned her off of sex for the next two weeks. You can call me an ass or a dumbshit but seriously think about it for a moment. This was going to be a major emotional roller-coaster for me.

        I'm reminded of some poor sap here on slashdot who was telling us what it's really like to have a nympho girlfriend. It sounds great until you are presented with the reality of the situation, namely, that she absolutely needed sex every time he put his arm around her. Look, I still think that woman I dated was very desirable on many, many levels but I also think I did the right thing by stopping that relationship before I got sucked into her work as well.

    • How to deal with "pictures." (Score:4, Interesting)

      by Raindeer (104129) on Wednesday January 19 2005, @01:45AM (#11405544) Homepage Journal
      The Dutch police has a huge database of all kinds of (child pornography) pictures. Of each picture they have a hash. When they confiscate the pc of somebody who is suspected of having child pornography, the first thing they do is run the hashes against the pictures on the system. This saves them from having to look at all those pictures, they can now focus on the unknown ones. Great thing is also that the hashes are admissable in Court as evidence.

  • Encrypted disks? (Score:4, Interesting)

    by nizo (81281) * on Tuesday January 18 2005, @06:26PM (#11402490) Homepage Journal
    Not that I would ever have anything to hide, but how safe is data on an encrypted disk, in particular linux encrypted filesystems like this [sourceforge.net]? It seems to me that with a little encryption you would pretty easily foil the efforts of any local forensics people.
    • Well, maybe. The issue is password protection. If "they" have access to your computer early on, and they almost certainly would, they can put in a keyboard sniffer to snatch your password -- and there goes the safety afforded by your encryption, no matter how robust the algorithm itself may be. There are ways around this, but I've rarely seen them discussed, much less implemented.
      1. It sounds like the book is mostly about situations where the owner of the system wants to know what, if anything, was changed, and how the hacker got in, etc, as well as the owner provideing information to law enforcement.
      2. Notice the section

        A crucial decision that must be made during an incident is whether to shut down the system or let it remain on-line. There are advantages and disadvantages to each approach, and the book details them.

        ?

        Encrypted filesystems do no good if the filesystem is still mounted

    • Re:Encrypted disks? (Score:4, Interesting)

      by Grond_the_Hammer (784712) on Tuesday January 18 2005, @06:40PM (#11402620)
      It depends on what you mean by "local forensics people". Most true forensics professionals are pretty good at what they do, and I haven't yet met one that wasn't. People don't typically get jobs like that without going through a decent amount of training and certification.

      The mere presence of encrypted data is usually a tip-off to a decent examiner that something interesting is in there. There are even programs and statistical methods for finding different types of encrypted data on a drive. And there are all sorts of ways to recover passphrases...if you have enough evidence to get the suspect to talk, they'll usually give it up. Not every forensic technique is a technical one...

      Most of all, there is a lot of data that can't be encrypted to cover one's tracks, especially in the corporate environment where firewalls and other security systems log activity.

    • Re:Encrypted disks? (Score:2, Informative)

      by Anonymous Coward
      With a decent encryption method, you can almost guarantee that the data is secure. The better the encryption is, the larger the server farm/super computer they need to crack it. Although, it can be seen as contempt of court if you are required by law to give them the keys used to encrypt it and you fail to do so. Just because the data is unreadable by them doesnt mean they cant put you in the slammer.
    • Robert Morris Sr. once told an audience that cryptanalysts in real life follow the rule "look for plaintext, it shows up in the darnedest places".

      F'rinstance: suppose you're in the Middle East but you've carefully stored all your images of women without veils onto an encrypted volume. Suppose you looked at them one day. JPEG files typically open into a web browser. No matter how encrypted your stash was, the images are still sitting in the browser cache.

      Today's crypto is as strong as your passphrase(*). C

  • Scientists don't do police work (Score:3, Insightful)

    by Quill_28 (553921) on Tuesday January 18 2005, @06:27PM (#11402508) Journal
    >Where such shows deviate from reality is the
    >unrealistic speed at which the actors are able to
    >identify, apprehend and prosecute the perpetrators.

    What is also unrealistic is that the CSI guys ever see a suspect. The go to the crime and spend the rest of the time in a lab or sometimes in court.

    They would never ever talk to a suspect.

  • Forensic Science (Score:4, Interesting)

    by exp(pi*sqrt(163)) (613870) on Tuesday January 18 2005, @06:36PM (#11402586) Journal
    The primary purpose of forensic science is to pretend to be a real science so as to fool people into thinking that there are reliable ways of tracking down who you are if you commit a crime. It's the myth of forensic science that keeps the crime rate down, not actual forensic science successes. Ask N forensic scientists when someone died, how long it was since their last meal and so on and you'll get N differet answers. But programs like CSI help to mislead people into thinking this stuff actually works.

    In the days of yore the torture was used much leass than people imagine. Just the threat of torture was enough to make people confess. The same goes with forensic science. A cop says: "we have your DNA and we know it's you for sure" and that's enough to make someone confess. And as long as programs like CSI keep airing people will continue to fall for it.

    In fact, the fact that forensic science is 90% bull is probably one of the best kept secrets left in the Western world.

    • References? Evidence? Even CSI is a better authority in my mind than someone who provides no information to back up his claims. At least I know CSI did some research into making the investigative process look realistic.
    • there's a BIG difference between torturing and claiming that you have evidence.

      with torturing people would confess things they had not even done.

      you don't need dna to prove that someone was somewhere at some time.. there's lots of other ways. usually someone saw them or you could follow them home or there was some other way to trace them to the crime.

      tv forensics is 90% bull.. but what has that do with techniques used by real life cops?

  • I don't care. (Score:4, Interesting)

    by AceCaseOR (594637) <alexander...case@@@gmail...com> on Tuesday January 18 2005, @06:38PM (#11402605) Homepage Journal
    Where such shows deviate from reality is the unrealistic speed at which the actors are able to identify, apprehend and prosecute the perpetrators.

    Frankly, I don't care. I don't care that in reality it would take 3-4 months to get the DNA processed because of the massive queue of other cases that need DNA processed. I don't care that real-live CSIs would never, ever, ever see a suspect or a crime scene. You can't really do a series that way. I don't have cable or sattellite so I haven't seen the show, but I doubt that even New Detectives goes without showing the suspects.

    I like have interesting characters, I like a good story. That's I still read Agatha Christie novels and watch the Poirot mysteries, even though Christie cheated on a regular basis.

    Just my $.02

  • For starting out [dummies.com]. (Will they have Phishing For Dummies next?)
    • The OP's link is to a Dummies book, "Forensics for Dummies"... The blurb reads 'Now, everyone can get the lowdown on the science behind crime scene investigations. Using lots of fascinating case studies, forensics expert Dr. D. P. Lyle clues people in on everything from determining cause and time of death to fingerprints, fibers, blood, ballistics, forensic computing, and forensic psychology.'.

      Then, lower down the page, in the Related Articles section...

      - Acquiring Kitchen Equipment for Your Restaurant

  • Security luminaries Dan Farmer and Wietse Venema wrote one of the first vulnerability scanners (SATAN) almost 10 years ago; SATAN was the precursor to ISS Scanner, Retina and nmap. Venema wrote such well-known security applications as the TCP Wrapper program and the Postfix mail server.

    SATAN was also known as SANTA to those sensitive to sacrilegious references. Also, it's TCP Wrappers.

  • I'll Bite... (Score:4, Interesting)

    by Gargamell (716347) * on Tuesday January 18 2005, @06:57PM (#11402827) Homepage Journal
    Hi all,

    Noticed that this post was hovering around 30 posts, and so i thought i would toss in some relevent tidbits that are pretty interesting.

    I graduated with a CS degree, and now i run a data warehouse, and architect an enterprise java application. Things are going well, but as many of us are aware, it may not be going so well for everyone that just graduated...

    case in point - a buddy of mine got a good job out of school, but it isn't great, not like what we all pictured when we signed up in the midst of the boom 5 years ago! About a month ago, an old friend of ours called up and said he had positions available for Forsenic Scientists (paid bank). I kept asking what portion was related to CS or technology, and he kept replying - NONE! The only part is the ability to methodically research details and clues! Can anyone say.... debugging?!

    Anyways... i started to think about it, and compared with some of the criminal justice majors i know, CS grads really are more capable to handle that kind of stuff. Just like abstract puzzles, RPGs, and even some of the "lock-picking" articles i have been seeing. Anyone have a simliar tale? Anyone know of a school that has a curriculum that tailors to that kind of profession?

    Thanks! ~tim

  • Cut TV some slack (Score:4, Insightful)

    by Jerf (17166) on Tuesday January 18 2005, @07:26PM (#11403168) Journal
    unlike television, where the crime must be solved by the end of the family hour

    Have you thought about what you're (implicitly by your implied criticism] asking for?

    Which is it you want, an "episode" that lasts three months? A season that consists of the same 20-ish (or whatever number) episodes it does now, only randomly scattered across the episodes in the order in which they "really occurred"? On every scene change, white text on the bottom of the screen that says "[random time period] later"?

    It's like asking for "total realism" in science fiction... you are aware that faster than light travel is, at best, totally unproven and most likely completely impossible? (Save the discussion on the possibility of FTL for sci.physics, please, this is just an example.)

    So many fan-boy types ask for things that if they got them, they'd hate even more. I for one am glad the characters aren't making constant references to the amount of time something is taken, and I for one am glad that when they dig through an entire day of garbage in Los Vegas, they show about ten seconds of walking around, followed by the necessary discoveries. Are you seriously asking them to show the five or six hours it might have taken in real life? You feel free to watch it, I can guarantee I wouldn't.

  • What's next? (Score:3, Insightful)

    by StikyPad (445176) on Tuesday January 18 2005, @07:29PM (#11403203) Homepage
    You're telling me that it takes longer than an hour to solve a crime? I've been to football games -- I know that what's on the TV is what's actually happening in real time. If it's on the TV, it must be real.

    Besides, who wants to watch a show where they uncover one clue a week, or get a subpoena, or nothing happens that week? Surprisingly, people don't want to watch real life when they turn on the TV (and don't even try to say that reality TV has anything to do with real life).

  • Forensic Discovery Fraud (Score:2, Interesting)

    by Anonymous Coward
    I've got lovely news for you: Unless you are able to watch a computer from the time it is put on the network to the time that removed for evidence collection, you can say *VERY*LITTLE* about what someone may or may not have done with that computer.

    Here's a little story from several years back. A friend of mine who was doing deployed support for one of the armed services used an account at a major American university, which he was authorized to used, to download/store updated cisco images due to limited b
    • Right... This guy had a decently bad experience. Everyone makes mistakes. Obviously this case had a fair bit of incompetence, but I doubt this is the standard. Also, keep in mind that 90% of what is termed "Computer Forensics" has nothing to do at all with network activity. Computer Forensics deals mostly AFAIK with such things as: 1. A suspected pedophile is arrested, and they pull his computer. They find stuff like kiddie porn, and MSN logs where he tries to get little ones to meet him in the park e
    • Forensic Files is another great show. I guess these types of shows, while still entertaining, cater to those who prefer their gore with a little more grey matter :)

      CSI isn't too bad, but compared to ogrish.com, "it ain't shit" :)
      • My problem with the CSI-type shows is that forensics analysts are more like Quincy, who rarely, if ever, interviewed a suspect or a witness, and got in major trouble when he did.

        The "examiners" on CSI do everything except commit the crimes, give parking tickets and prosecute the suspects. If I could do half of what one of them does, I'd be an unstoppable law enforcement agent!
    • Unfair comparison. The whole time issue is all based on pacing. The big time-waster when it comes to forensics is DNA analysis, as that department is generally the department that gets it in the pants when it comes to the budget.

    • Re:That is why CSI sucks (Score:5, Informative)

      by severoon (536737) on Tuesday January 18 2005, @06:41PM (#11402633) Journal

      I especially hate it when (this seems to predominate on CSI, but I've seen it on other shows as well) they "digitally enhance" security camera video to identify an attacker, read a license plate, etc. Usually, I can overlook it for the sake of the plotline every now and again. But, the final straw came for me a few weeks ago on CSI when they had an ATM security cam and the pulled a reflection off of the pupil of the third person in line and enhanced it to ID the criminal (second in line) who was facing away from the camera. They literally took a single grey pixel from the video and "enhanced" it to a beautifully rendered, studio-lit 8"x10" black and white portrait of the criminal.

      And, oh yea, if you put deer feces into an NMR, it's not going to spit out a graph with a bunch of peaks on it and print below the graph: "deer feces". On the other hand, I'm not sure which is worse...when they do that with the NMR, or when they NMR identifies 50 compounds in a sample, all with names like "n-methyl hydride deoxynitrate", and the CSI goes, "Oh, yea, those are the major components of plumber's grease that was used between 1970 and 1978 in the Western United States." They might as well have the NMR spit out a graph with a caption: "The bus driver did it! The motorcyclist was only his *accomplice*."

      Then, of course, there's the small issue of unlimited budget. If real CSIs solved crimes like they do on TV, they'd be spending somewhere between $15M and $50M per case. :-)

    • It may not be exactly true but it is clearly based on various people. Some mental disorders enhance other parts of people, so where as Monk may hate disorder his eyes focus on it so he notices the things out of place. The same could be said of many people with similar disorders to his.
      • Monk is also based on a lot of classic detective fiction, especially Holmes. Many of the characters, themes and plotlines are similar to those in the Holmes stories.

        Makes it much more entertaining than CSI, IMO. Character and story take priority over fake techno-speakery.

    • It is based on a true story isn't it? Isn't it!

      Yeah, Monk is what Rain Man became when he grew up.

    • Frankly, every fiction TV show and movie that has picture enhancement of video from anything has pulled this conceit. The list of series and movies that haven't done this will definatly be much, much, shorter than the series that have.

    • > The thing I hate most about CSI is...

      A couple of recent "I hates" that come to mind:

      Getaway car peels out, leaving rubber on the pavement. The tread pattern is perfectly preserved in the squeal mark. (They even see a black spot from a nail in the tire.)

      In the morgue, they push some kind of putty into a stab wound in the body cavity, and pull out a cast showing the shape of the blade that made the wound (down to the detail of a broken tip),

      Other gripes about CSI and all the other recent crime show

    • Re:Computer Forensics = FRAUD (fbi puts files in) (Score:5, Informative)

      by DoctorMabuse (456736) * on Tuesday January 18 2005, @07:02PM (#11402886) Homepage
      This poster is totally incorrect. I have served as a computer forensic expert in both civil and criminal cases, and can tell you this poster does not understand the process. For example, the prosection and defense may find an impartial examiner or use two examiners and make two copies of the seized disk or disks. Forensic tools with copy capabilities such as EnCase will make a bit-for-bit copy (including non-allocated sectors, file slack space, etc) of the disks and perform an MD5 checksum over the contents.

      I now perform my work on the copy. Any results I obtain can be demonstrated in court, as can the fact that the MD5 hash is the same and that my disk is still identical to the other party's copy.

      If chain of evidence is maintained, I should get the disk as it was when it was seized. Once I have it and copy it, it is effectively tamperproof, because of two persons each having a copy, the MD5 hash, additional checksums built into EnCase copy structures AND the fact that we can always recompare our copy to the original to determine it is still bit for bit.

      The scientific validity of computer forensic methods can be subjected to a Frye or Daubert hearing, where scientific experts can defend the method. EnCase has already been through these hearings and no credible argument has been advanced against its validity.

      If you competent defense counsel or civil counsel, this should not be a concern.
      • DoctorMabuse,

        I also use EnCase when I do forensics work, and prefer the SHA-1 hash features in it :). One of my customers is large enough to have their own copy, and access to iLook if needed.

        However, the procedural work that has to be done before an evidence disk gets into my hands is just as, if not, more important than the actual evidence. Even when it comes to log files, I have to follow a very firm set of procedures, starting with the md5 checksum of the files, before I even start. I also have to

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