File System Forensic Analysis

nazarijo writes "The field of investigative forensics has seen a huge surge in interest lately, with many looking to study it because of shows like CSI or the increasing coverage of computer-related crimes. Some people see a career opportunity there, and are moving toward computer forensics, marrying both law enforcement and investigations with their interest in things digital. Central to this field is the study of data storage and recovery, which requires a deep knowledge of how filesystems work. Brian Carrier's new book File System Forensic Analysis covers this topic with clarity and an uncommon skill." Read on for the rest of Nazario's review. File System Forensic Analysis author Brian Carrier pages 600 publisher Addison Wesley Professional rating 9 reviewer Jose Nazario ISBN 0321268172 summary The standard for digital filesystem forensics

It's easy to think that computer filesystems are relatively simple things. After all, if 'dir' or 'ls' don't show what you're looking for, maybe an undelete program will work. Or will it? To be a decent, trustworthy expert in forensics (a requirement if you plan to participate in any criminal investigations), you'll have to learn how filesystems really operate, how tools like undelete and lazarus work, and how they can be defeated.

Carrier's book isn't a legal book at all, and it doesn't pretend to offer much insight into the law surrounding forensics. Instead it focuses on technical matters, and is sure to be the gold standard in its field. This is important, because it comes at you expecting you to have some knowledge, even if only informal, of what a filesystem contains. With a basic understanding of data structures, you'll get a wealth of information out of this book, and it will be a good reference long after you've first studied it.

File System Forensic Analysis is divided into three sections. These are arranged in the order that you'll want to study them to maximize the benefit you can hope to achieve, namely an understanding of how to examine filesystems for hidden or previously stored data. The first three chapters cover a fundamental series of topics: Digital Investigation Foundations, Computer Foundations, and an introduction to Hard Disk Data Acquisition. While they start at a basic level (e.g. what hexadecimal is), they quickly progress to more developed topics, such as the types of interfaces (SATA, SCSI, IDE), the relationship of the disk to the computer system as a whole, and how data is stored in a file and filesystem at a basic level. A lot of examples given use Linux, due to the raw, accessible nature of UNIX and UNIX-like systems, and the availability of tools like 'dd' to gather data.

Part 2 covers "Volume Analysis," or the organization of files into a storage system. This introduces the basics of things like partition tables (including how to read one). The next few chapters cover PC-based partitions (DOS and Apple), server-based partitions (BSD, Solaris and GPT partitions), and then multiple disk volumes like RAID and logical volumes. With this introduction, the final chapter of the section covers how to use these filesystem descriptions in practice to look for data during analysis. Filesystem layouts, organization, and things like journals and consistency checks are covered with a clarity and exactness that's refreshing for such a detailed topic.

Having covered the basics of filesystems, Part 3 covers the bulk of the book and material. Several chapters follow that specifically show you how to analyze particular filesystems by using their data structures to direct your reads. A range of filesystems are covered, including FAT, NTFS, EXT2 and EXT3, and the BSD types UFS1 and UFS2. Each filesystem has two chapters, one devoted to concepts and analysis, another entirely about data structures. Dividing each filesystem type like this lets Carrier focus first on the theory of each filesystem and its design, and then the practical use of its design to actually understand how to pull data off of it.

The real strength of File System Forensic Analysis lies in Carrier's direct and clear descriptions of the concepts, the completeness of his coverage, and the detail he provides. For example, a number of clear, well-ordered and simple diagrams are peppered throughout the book, explaining everything from allocation algorithms to NTFS alternative data streams. This use of simple diagrams makes the topics more easily understood, so the book's full value can be appreciated. This is the kind of thing that sets a book apart from its peers and makes it a valuable resource for a long time.

Finally, Carrier brings it all together and shows us how many aspects of filesystems can be examined using his "sleuth kit" tools, freely available and easy to use. Without appearing to hawk this tool at the expense of other valuable resources, you get to see how simple and direct filesystem manipulations can be done using a direct approach. This kind of presentation is what makes File System Forensic Analysis a great foundation.

Overall I'm pleased with File System Forensic Analysis, I think that Carrier has achieved what few technical authors do, namely a clear explanation of highly technical topics which retains a level of detail that makes it valuable for the long term. For anyone looking seriously at electronic forensics, this is a must have. I suspect people who are working on filesystem implementations will also want to study it for its practical information about NTFS. Overall, a great technical resource.

You can purchase File System Forensic Analysis from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.

Comments

STEP ONE

[jos3000]

Don't forget to mount the drive as read only!

Re:STEP ONE

[MyLongNickName]

I, for one, do not want to know about your personal life. Thanks.

CSI

[Seumas]

Why in the hell would you choose a dull career like forensic investigation based on a TV show? That would be like becoming a cop because you want to be like Dirty Harry. How many of these gits go into college for this kind of career, because they think it's going to be exciting and they're going to discover the case-cracking evidence in a few hours, grab their gun and go make an arrest?

Re:CSI

[Brento]

That would be like becoming a cop because you want to be like Dirty Harry.

Or becoming a hacker because I wanted to meet Sandra Bullock. Man, what a time-waster this has turned out to be.

Re:CSI

[abb3w]

Why in the hell would you choose a dull career like forensic investigation based on a TV show?

Or engineering? After all, if ya canna change the laws of physics, where's the fun in it?

Monkey see, monkey do....

Re:CSI

[jpostel]

I wanted to meet Angelina Jolie... I should have become a cambodian orphan instead.

Re:CSI

[That's Unpossible!]

Why in the hell would you choose a dull career like forensic investigation...

As opposed to an exciting career, like computer programming?

Seriously, I do a lot of programming as part of my job, and perhaps the most fun I have at work is when some luser decides to fuck with us and I get assigned to track down as much information as possible about this person's activity on our network.

If I ever had to find another job, I'd seriously consider getting into computer forensics, or the FBI computer investigation division.

Just because you don't go make an arrest doesn't mean your discoveries won't directly lead to an arrest. And usually the best kind ... when the loser is least expecting it, because they didn't think anyone was sharp enough on the other end of the line.

Re:CSI

[Shanep]

Why in the hell would you choose a dull career like forensic investigation based on a TV show?

Computer forensics does not always have to be dull.

You can sometimes do things you ordinarily would not be allowed to do, because you are doing them to "assist the court", sometimes which explicit blessing from the court in the form of a court order. Reverse engineering, network packet analysis, log file analysis, filesystem analysis, cryptography (algorithm deduction, password cracking), statistics, data mining. Using sniffers, hacking tools, debuggers like IDA Pro, getting to use devices not available to the public, etc.

It does not have to be boring. And the more you delve beyond the superficial, the more rewarding it is to find evidence yourself and others had missed.

It can actually be very exciting.

Re:Your rights online?

[hal9000(jr)]

I would say a book on how to snoop on people hard drives and see what they deleted is pretty privacy invasive? Most legal investigations are invasive by their very nature.

Here is an even better question

[crow_t_robot]

How long will it be before there are a million "IT Forensics" certification mills out there advertising on the radio to knuckle-dragging GEDs to come get certified and make $$$ in this "HOT, NEW, EXCITING INDUSTRY!!!"

Re:Here is an even better question

[Seumas]

Will they have to have wavy blonde hair and wear pink polo shirts and go to Brown College? :P

That's probably one of my bigger pet peeves. People in technology jobs who are not passionate about technology. You see it all the time, unfortunately. You don't have to be passionate about your current job - but you should be passionate about tech.

I mean, you wouldn't go into teaching if you didn't care about teaching, right? (At least, initially).

Re:Here is an even better question

[MrAnnoyanceToYou]

The computer industry could use an infinite number of women with wavy blonde hair, pink polo shirts, and a good education, as far as I'm concerned.

Re:Here is an even better question

[myowntrueself]

"That's probably one of my bigger pet peeves. People in technology jobs who are not passionate about technology."

One of my pet peeves is people who work in technology jobs who are passionate about technology to the point where they will convince a client to go for the latest, most bleeding-edge technologies for their most critical, sensitive, 'must never go down' applications.

I prefer a cautious approach when it involves getting woken up at 3am on a regular basis because some *geek* decided to use something that had never been properly tested, had only just been released, that noone else in the company has ever used, for some production system... thats when I get that murderous blood-rage for people who are 'passionate about technology'.

I might get this

[L. VeGas]

This sounds really interesting. I've been fascinated for a while with how the file / folder metaphor has become so entrenched that people have a difficult time imagining any other way of thinking about it.

As the OS has become more sophisticated, most computer users now never see things like a disk defrag. They really think that there is a file, all in one spot in their computer, that sits literally next to other files in the same folder. The idea that you can recover a file that has been "deleted" seems like deep wizardry, with no thought to the more impressive wizardry that makes "files" out of pieces of metal with a magnet.

Other views on the book

[sidney]

For alternate opinions on the book see this review by Rob Slade in RISKS Digest, and this short rebuttal of Slade's review by Simson Garfinkle.

STEP ZERO:

[abb3w]

Make sure by ordering the right adapter for doing forensic's work that Your Young Apprentice (or PFY) can't screw this up. A read-only adapter means the drive can't be mounted rewritably. No, it's not cheap. But what's $500 to the assurance that your evidence chain is prevented from fuckup at the hardware level?

And no, I don't work for these people. I just think they make some nifty geek toys.

No, that's not why I have SCSI drives on my home server. Honest; it's for the RAID performance....

Re:STEP ZERO:

[pegr]

Make sure by ordering the right adapter for doing forensic's work that Your Young Apprentice (or PFY) can't screw this up.
 
Well, instead of using an OS that does what it damn well wants (like mount all drives read/write by default), why don't you use Linux and simply create a drive image straight from the raw device without mounting at all? Gen an MD5 on the fly to ensure integrity. Use DCFLDD instead of dd for that trick...
 
Funny story: I was in a training class and the topic turned to forensic analysis. I mentioned that the Air Force wrote a wonderful tool, the previously mentioned DCFLDD. Well, this math geek that I was certain worked for some three-letter outfit turned around and looked at me like I was spewing nuclear launch codes! After I assured him that the Air Force open sourced it (and brought up a download URL on his laptop), he seemed to get the clue...
 
Since he's also a likely slashdot reader, "Hi Dave!" ;)

Re:STEP ZERO:

[computational super]

Funny story

You keep using that word. I do not think it means what you think it means.

Re:STEP ZERO:

[randomblast]

Why is it always a Dave?

Re:STEP ZERO:

[COMON$]

Why use an OS at all, there are plenty of imagemasters out there logicube has some nice ones that I have used personally. Sure they are pricey but you can do whatever you want to the cloned drive, mount it, run its OS to see what kind of setup the offender had, rip out items, delete, add run hashes, whatever you want and not worry about hurting the original drive sitting across the room from you in an antistatic bag.

Re:STEP ZERO:

[Shanep]

Well, instead of using an OS that does what it damn well wants (like mount all drives read/write by default),

I agree, gathering evidence with Windows sucks.

why don't you use Linux and simply create a drive image straight from the raw device without mounting at all?

Because in court, things can get nasty like this...

Barrister: Did you use a (looks at freshly written note) "write blocker", Mr. Smith?
Forensics guy: No, I did not need to. I refrained from mounting the disk and copied it at a raw block-for-block level (confusing to judge).
Barrister: Yes or No Mr. Smith, did you use a "write blocker".
Forensics guy: No.
Barrister: And a "write blocker" is a forensics industry standard method for preventing contamination of captured evidence? (Judge respects witnesses who respect the court enough to make sure their captured evidence is absolutely accurate and original evidence could not have been altered).
Forensics guy: Yes, but...
Barrister: Mr. Smith, you failed to take a basic precaution to make absolutely certain that the captured evidence was not altered in any way, by using a basic device that is normally a part of the toolkit of a computer forensic professional. Do you posess a "write blocker" Mr. Smith?
Forensics guy: Yes (No).
Barrister: Then WHY did you not use it?! (You ARE a computer forensics professional are you not Mr. Smith?)
Forensics guy: gasp gasp (blush) choke...

The point is, if you are gathering evidence of this sort, then write blockers are tools you should have and always use. All the opposition needs to do is raise doubt. And then you and your client are screwed.

When you take the stand or put on an affidavit, the opposing legal team will attack:

1/ Your findings and the methods you used to get to them.
2/ Your evidence.
3/ You credibility.

and at a worst case...

4/ Accuse you of tampering with ORIGNAL EVIDENCE which has been tendered to the court!

Not having a write-blocker says, "I am not a computer forensics professional".

Having a write-blocker and not using it says, "I am sloppy and failed to use a simple tool at my disposal to assist the court as best I could".

Whether your evidence is exactly the same as the other forensics experts is beside the point. They have attacked your credibility and that can go against your findings (even if they are completely correct). You have nothing to gain from not using a write-blocker (which you should already have) and everything to loose. I would love to just capture evidence with FreeBSD and just copy from the raw device. But at the end of the day, the cost of a $500 write-blocker, which you get to use over and over, should be peanuts compared with what you make each day you work on cases which requires its use.

Re:STEP ZERO:

[Shanep]

Uh, most drives have a write-protect jumper on them.

Even if the HDD you were capturing evidence from had a write-protect jumper, the point of a write-blocker is that it removes doubt. You plug it in and it will not allow writes to the drive. You don't have to worry about what jumper to short, etc. A simple and absolute solution leads to a simple and absolute statement on the stand.

BTW, can you point me to a HDD which has a write-protect jumper? I don't recall ever seeing one.

Re:STEP ZERO:

[pegr]

Why didn't you let the fucker twist in the wind?
 
Cause he was otherwise a very cool guy. Standard with-clue geek with other character redeeming characteristics... Not everyone who works for Uncle Fed is a mindless drone. Especially this three-letter organization... (Come to think of it, he was leaving Uncle Fed to start his own practice.)

Re:STEP ZERO:

[Shanep]

Ultimately such a device merely relocates the nexus of trust and fails to actually improve the surety of the evidence.

I agree with a lot of what you have said. But...

Court cases are all about being most convincing to a judge and sometimes a jury. They typically don't understand the technical issues, so expert witnesses are expected to explain the findings in an accessible manner.

Write-blockers do however work and are expected to be used. There is little to go wrong with a write-blocker/expert combination and a lot more that can go wrong with a software/expert combination.

You do the best for the court and write-blockers provide the best solution for capturing evidence accurately without modifying the orignal. You can't accurately capture original evidence if the act itself alters it, even if ever so slightly.

What you have to understand though, is that even if you are the best computer forensics expert to have ever walked the Earth, the barristers on the opposing side NEED to find fault with you, your findings and your evidence. They do it for a living and they are really good at it. That can take a small issue and have your evidence and findings thrown out.

Because such a device is Kludge. It is a black-box that cannot be verified and as such as is no better than the "black-box" of the operating system.

I would not call the forensic quality write-blockers on the market "a kludge". They perform a basic role to a level that is accepted by the highest courts and experts (the real ones). They are very simple, yet vital. They go a long way to preventing human error.

Moreover, the latter is used and effectively tested by millions whereas only a handful of people purchase such "write blockers"

The software in question is extremely complex and has to be driven by an error prone human. The write-blocker on the other hand, is a very simple device dedicated for one thing and is simply plugged into the drive to be captured.

Re:The "How To Destroy Your HD" Thread

[Gnpatton]

Install an old version of windows, unpached with no firewall protection.

2 other great books I have used...

[Anonymous Coward]

I suggest getting: Incident Response (Kevin Mandia and Chris Prosize) and also Computer Forensics (Warren G. Kruse and Jay G. Heiser). Both are an excellent read, and the Mandia book has some wonderful documents to use for real-life situations.

Forensics? Wouldn't know it from the review

[Red Flayer]

In all, a good review of the book. However, the focus on forensics is left out of the review -- just wanted to point out that the book is more than a text on file system management, search, and data recovery.

Although, of course, the book does a very good job of being that as well.

Re:The "How To Destroy Your HD" Thread

[abb3w]

A nice gob of thermite over the drives

Custom built 5.25" bay metal box, front side key locked switch controlling 12v powered spark igniter for magnesium primer charge; remainder of the box filled with thermite. Install in the computer's top bay. You can generally get all the way through at least eight drives that way, but if you have vertical mount drives, you'll want a second kaboom bay in the lowest 5.25 bay. Have a good UPS, and have a metal-bottomed water tank below the computer (camoflage as an overclock device), because that much thermite does NOT stop quickly.

They can pry my PGP key from my computer's cold dead... um, slag. =)

people who bought this book also bought:

[museumpeace]

a series of how-tos and standards docs
At the behest of the DOJ, NIST has been grinding out standards on how to forensically analyze a hard drive an other arcana for several years now.

NIST even provides tools: http://www.cftt.nist.gov/

New TV show..

[Bnderan]

I will look forward to watching SCSI-Miami.

What about encryption?

[tacokill]

I know that encryption is a topic unto itself but it is becoming more and more common for people to create PGP Disks or DriveCrypt disks.

How do those things fit into this topic? I mean, the filesystem stuff is great and interesting but it doesn't seem to do any good if all you can recover is a PGP Disk file*.

Can someone much smarter than me tell me how data forensics deals with that????



* PGP Disk: a pgp encrypted file that can be mounted as a drive letter. It is, literally, a file just sitting there on your harddrive. You mount the file (after providing the secret passphrase) and voila! - you now have an encrypted drive to copy files in and out of.

Re:What about encryption?

[jonadab]

> tell me how data forensics deals with [a PGP Disk file]?

First you recover the PGP Disk file, using the sorts of techniques discussed in the book this review covers. Then you apply cryptanalysis, using the sorts of techniques discussed in cryptography and cryptanalysis books.

I do this sometimes...

[MarcQuadra]

I do 'forensics' sometimes. I was freelance fixing computers for a while when one of my clients asked me to find out what her husband was doing online. For a princely sum I began doing 'stealth' missions for many distressed spouses. I uncovered a lot of dirt and presented it with the understanding that I never be named or asked to testify.

Morally, it's a dark-grey zone, but it payed well and I provided the hard evidence needed to end a few broken marriages. All my former clients are better off after they found the truth.

It was odd explaining to the ladies that the VAST majority of men on the web look at porn, and that it's not anything to worry about. I was looking for personal ads, dating sites, child or extreme porn, and S&M personals sites.

It's exciting to get the call at 8am to come and clone a drive on-site. I then take it home and get what I can from it however I can, from mounting and browsing to hexdumping and grepping.

Re:I do this sometimes...

[Dogtanian]

I was looking for personal ads, dating sites, child or extreme porn

What the heck is 'extreme porn'?!

People f*****g on snowboards at 120MPH? Some naked chick with massive fake breasts doing skateboard stunts on a halfpipe while guys standing at the top on each side try to bukakke her while she's paused in mid-air?

"It's not XXX rated.... it's XXXTREME rated!"

Re:I do this sometimes...

[Johnny Mnemonic]

For a princely sum I began doing 'stealth' missions for many distressed spouses.

I'm glad that I use OS X's encrypted home directory, then. I guess you won't be reading my files. You could change my pass by booting to CD (and then I'd know!) but you still couldn't get to my home dir.

Seriously, you ever run into a Mac that had more than a passing effort made at security, and if so were you able to get around the safeguards? Or did you just sub that out?

fwiw, I guess if they wanted you to testify you wouldn't have much of a leg to stand on--a subpoena is a subpoena, and you would either have to ignore it, respect it but stay silent, or 'fess. All would involve legal fees, and I think it could be construed as not legally admissible evidence. In any event, if I was the husband's divorce lawyer, I would ask you some sharp questions.

Re:I do this sometimes...

[techno-vampire]

...and S&M personals sites.

Did you ever find one and have the wife respond, "If I'd known earlier he liked that, I'd have given him all the S&M he wants. No need for him to look elsewhere."

Re:I do this sometimes...

[JoeBuck]

"I'd be happy to beat the crap out of him!"

Related Links

[jkitchel]

Related links:
Digital Forensic Tool Testing Images
Brian's Tools - Includes links to SleuthKit and Autopsy
Forensic Tool Kit free trial

FTK is a nice tool to play around with for Windows users, especially with the testing images. The free trial does have a limit of 5,000 files per image so if you create or work on testing images you may have to get rid of extraneous junk and leave the good stuff. SleuthKit and Autopsy are great for the *nix environment. After you get those tools working you might give Scan of the Month challenges 24 and 26 from The Honeynet Projecta shot. They're both pretty fun and challenging. Don't worry if you don't know what you're doing. Both of the challenges have writeups done on how to accomplish the tasks and what tools were used if you need guidance.

Re:Related Links

[Stibidor]

Another nifty tool from AccessData that plugs nicely into the FTK is the Registry Viewer. Using the FTK you can find all the Windows registry files on the drive. The Registry Viewer (obviously) will open them and allow you to view just about any key/value including encrypted keys like the Protected Storage (Internet Explorer autofill and Outlook/Outlook Express saved passwords).

Since I enjoy tooting my own horn from time to time, the information referenced in this article was obtained by me and my co-worker (I shamelessly admit to working for WhiteCanyon) using AccessData's FTK and Registry Viewer. It was quite a bit of fun to see our results hit national T.V. :)

Re:That is just great

[hoggoth]

> Mmmmm young girls...

You'd better hope nobody does a forensic analysis of YOUR filesystems.

Crooks are going to read-only + encryption

[davidwr]

Crooks who are "smart" are going to encrypted systems and making darn sure there's no unencrypted writable storage lying around. This, plus tamper-evident computer including tamper-evident keyboard and keyboard-connectors and a faraday cage makes it very hard on the police.

Can you say "boot with Suse Live CD and encrypt /dev/hda"? I knew you could.

This only works in jurisdictions that can't force you to reveal your passphrase. In those jurisdictions, smart crooks outsource thier IT to North Korea :).

That still leaves plenty of forensics work for criminals using other people's computers such as white-collar crooks and the 99% of crooks who aren't smart.

Re:The "How To Destroy Your HD" Thread

[hoxford]

You'll want more than a water tank below the computer since water doesn't stop a thermite reaction. Try a couple of layers of firebrick or some other ceramic that won't shatter due to exteme heat.

Having done forensic work...

[bradleyland]

Honestly, this job is probably the coolest I've done. We get the run of any joint we enter. We get to crack people's passwords, read their stuff, and pry into the details that they're trying to hide.

Outside of the unreal timeframe, it is a bit like television. I've been on location at 1 AM acquiring hard drives so that the debtor principles didn't know what we were doing. Walking through the data center with my mag light at that hour of the morning comes pretty close to that feeling you get when you watch CSI on TV. Most of the time, we tell the people on location we're making "backups" of the data so that we can preserve the data in the event of a crash. There's definitely a social element to forensic work (at least in bankruptcy cases).

A typical acquisition may go something like this:

You set up, pull your forms, start noting observations, pull the drives, hook them up to the little black box connected to your laptop's firewire port (a write-blocker), and start having a look at the data. If you've got what you're looking for, you acquire the drive and put everything back together. Boot it all up and be on your way.

You may be doing this in the CEO's office, or in the data center looking for a mail server. The top officers are usually the most important, since they have the most important correspondence and data.

It's a fun job. It's every bit as exciting as what you see on television (for once).

Re:Having done forensic work...

[Anonymous Coward]

Honestly, this job is probably the coolest I've done.

The adrenaline of solving the puzzle and turning up evidence which no other team has been able to prior is pretty awesome too.

I LOVE computer forensics. Nothing on TV comes close to how cool it can be.

Collecting evidence can be boring. But finding evidence that is intentionally hidden in really creative ways is exciting. Being creative in your methods is also fun and VERY VERY cool when it is a method nobody has ever used before for that problem. Especially when others around you are telling you that you are "going about it all wrong" and then it is *your* evidence and findings which become most important to the case.

MC

[Dogtanian]

If you don't want anyone to find out what you have been doing on your computer, then a hammer is the best choice.

I found that too... I got Hammer to defend my computer, and any time someone tries to take the drive away for forensic examination Hammer stops them by saying "You can't touch this!"

Re:The "How To Destroy Your HD" Thread

[ResQuad]

defenetly a little extreme, but as the other replier stated that water wont stop thermite very quickly. In reality you dont need that much distructive power to distroy a harddrive.

If I had my way, I'd just put a small shapped charge ontop of the harddrive. Small enough to distroy the harddrive (and probably some other stuff in the machine w/ fragmentation) but not big enough to blow up the entire machine. Cases are preety well built now adays, and with some re-enforcement they could take a small shapped explosion (that was not pointed at them). But this is all under the guise that you can get your hands on all this stuff.

What can the real person do to protect themselves is a better question. What quick/distructive meathods are there for the real person.

Morality of Privacy

[redelm]

You may be concerned that you violated someone's privacy. I would not be. You did not get anything that wouldn't be discoverable during divorce proceedings.

On a more fundamental level, privacy is a conditional right. A person has to behave in order to enjoy it. It is not a shield for wrongdoing. Moreover, in a marriage it is patently obvious that both are willingly giving up privacy. I have fewer qualms with spousal snooping than that on kids or employees.

But beware, the discoveries hurt!

Me, too.. I have done some of this work..

[Tikicult]

It's really profitable... I was charging $200 an hour. Spent a ton of time digging around on a bunch of CDs, a hard drive and thru a couple of email inboxes. Plus my client had a key logger.

cool stuff.

Bigger questions

[cpu_fusion]

Rather than being so worried about what is there or not, the deeper and far more difficult question is: why is it there?

With the existence of zero-day exploits, spyware-zombies-for-sale, broadband, etc., how can anyone convince a jury beyond a reasonable doubt that someone put the bits there THEMSELF without a confession or video of them actually putting the content there?

People are going to jail because of this shit. Digital evidence is an oxymoron.

Re:Bigger questions

[BosHaus]

If you just have a random file or image of kiddie porn, I don't think that you can prove anything. But if you are looking and see file histories, downloading programs, gigs of data, etc that all point to something illegal, then you can make a case. I would doubt any spyware or zombie would actually go through the trouble of creating the whole path of crime.

Re:Bigger questions

[sinewalker]

It is an interesting question, "how did it get there?". I feel confident that I could not be framed convincingly, merely by somebody placing contraband on my PC and making it look like I did it, because if the judge/jury don't ask this question, my defence lawyer would. I fail to see how I could be convicted unless there were additional evidence (such as a trail showing how I got the file, or money transfers showing my purchase, or survailance showing me collecting CD's of kiddie porn from some supplier who they are staking out).

Do you have documented cases where someone was convicted solely on the evidence of files found on a computer? Show Us! This would definately have me worried. But I doubt there could ever be a case.

In order for a forensic investigator to even begin searching your computer, they have to have a good cause to sieze it. They won't get a good cause without other evidence that suggests you might have something to hide there.

Even if Mr.Enemy places such evidence on your PC (using info like in this book to make it look convincing) and then goes to the police claiming your are harbouring kiddie porn and he's worried you might be a distributor, they are going to ask how he knows (he saw it / you showed him it on your computer) and if you then say "but Mr.Enemy framed me" it becomes a he-said/she-said and they are going to need more evidence to convict. They won't neglect the posibility that Mr.Enemy placed it there, especially if Mr.Enemy had the access needed (long hours alone with your PC).

It's easy to be paranoid, but I really feel forensics like this to be much more helpful in leading to evidence that can convict, rather than to being the basis of a conviction itself. And for that I am grateful it's there as a tool.

Me too

[ari_j]

For a law firm, I investigated a drive that had been stolen by a former employee. The drive had been recovered, and my task was to determine what he had done with it and whether he had taken or tampered with any of the intellectual property on the drive. It paid very handsomely for the amount of work involved, and it was an intellectual challenge. That said, this book may have made it easier (I didn't read the review in-depth or the book itself, but I assume it wouldn't make the task more difficult).

In this case, I determined that the employee had mounted each partition on the drive to a separate mount point, not in the original structure (such as /, /usr, /home, and so forth; he had mounted it on /mnt1, /mnt2, /mnt3, and such).

It's not as glamorous as extreme porn or personal ads, but it was still interesting.

Re:Me too

[ari_j]

File access times. Word to the wise: If you want to copy all the files off of a hard drive, mount it read-only or make an image of it and work from that instead.

Actually

[DnemoniX]

You DO NOT want a water tray at the bottom. What makes you think a little bit of water will stop thermite? You need a tray full of sand. The thermite is hot enough to seperate the hydrogen out of water, not a great move.

Re:The "How To Destroy Your HD" Thread

[Seraphim1982]

I bet thermite is probably kinda hard to get your hands onto

Do you really think that aluminum and iron oxide are that hard to get a hold of? Anyone who has passed high school chemistry could make it.
In my experience it is harder finding a way to light the thermite then it is to acutally make the stuff.

Linux and juries - bad combination

[wsanders]

> why don't you use Linux and simply create a drive image straight from the raw device without mounting at all

Because once you start blathering on and on under cross-examination about raw devices, MD5 hash integrity, etc., the jury, which will probably consist of morons, will slowly doze off into la la land and blow off evrything you are saying.

Much better to spend $500 and tell the jury, "Jethto, Earlene, I got this here special dee-vice that physically prevents tampering."

To quote (fairly accurately IIRC) a juror in the Vioxx trial that just ended, "They started talkin' all that science talk and it was like - wah wah wah wah wah wah" (sound of the Teacher talking from the Charlie Brown videos).