Mount_EWF and Ubuntu 9.04

***Props to Steven Venter of Trustwave UK for putting this together. I used this today, with some minor modifications.***


So, I was faced with the need to mount a EWF image on my Ubuntu box so that I could use some of the TSK utilities on the image. Below, is how to get a tool called, "mount_ewf" working with Ubuntu 9.04.

So here's a quick update on getting EWF mounting capabilities installed on a new Ubuntu install [in this case the 32-bit version of Jaunty Jackalope Ubuntu 9.04]

The libewf software is now available at:
http://sourceforge.net/projects/libewf/

The files I downloaded were:
steve@jj:~/software/EWF$ ls -1
disktype-libewf.patch
EWF_file_format.pdf
libewf-20080501.tar.gz
libewf-beta-20090506.tar.gz *** I changed this too...I did NOT grab this file***
mount_ewf-20080513.py


== Install the required build dependencies
-- the required Debian packages in Ubuntu are: zlib1g-dev libssl-dev uuid-dev
$ sudo apt-get install zlib1g-dev libssl-dev uuid-dev

== Create Debian (.deb) packages to install
Since the downloads are now standard source code format, I tried to create Debian (.deb) packages using the guidance here: http://www.quietearth.us/articles/2006/08/16/Building-deb-package-from-source

***This took me awhile to get working properly, as the "how to" is kind of vague.

First off, let's install the necessary tools:
# apt-get install autotools-dev fakeroot dh-make build-essential

Next, take the tarball you downloaded, in this case libewf-20080501.tar.gz
uncompress the tarball
tar -xzvf libewf-20080501.tar.gz
cd into the newly created directory libewf-20080501

Now, you are going to use the dh_make utility to make the debian control files
dh_make -f /path/to/tarball <-- this is important. You have got to tell tool the location of the original tarball...presumably, just down one directory. In my case, I dropped my tarball into /usr/local/bin (which is where I drop all of my install files).

Then select "S" for single binary.

Then run the following: (this has to be done as root)
# dpkg-buildpackage -rfakeroot

Step 1: Install required dependency packages:
$ sudo apt-get install autotools-dev fakeroot dh-make build-essential

Step 2: Copy the source code tarball to /tmp and extract the contents there steve@jj:~/software/EWF$ cp libewf-beta-20090506.tar.gz /tmp/
steve@jj:~/software/EWF$ cd /tmp/
steve@jj:/tmp$ tar -zxf libewf-beta-20090506.tar.gz
steve@jj:/tmp$ cd libewf-20090506/
steve@jj:/tmp/libewf-20090506$

Step 3a: No need to make the debian control files, since they are already there [in the debian/ sub-folder]

Step 3b: Build the debian package:
steve@jj:/tmp/libewf-20090506$ sudo dpkg-buildpackage -rfakeroot
** this ended with the following output:
signfile libewf_20090506-1.dsc
gpg: WARNING: unsafe ownership on configuration file `/home/steve/.gnupg/gpg.conf'
gpg: skipped "Joachim Metz ": secret key not available
gpg: [stdin]: clearsign failed: secret key not available

dpkg-genchanges >../libewf_20090506-1_amd64.changes
dpkg-genchanges: including full source code in upload
dpkg-buildpackage: full upload (original source is included)
dpkg-buildpackage: warning: Failed to sign .dsc and .changes file
steve@jj:/tmp/libewf-20090506$

Step 3c: List the newly created files:
steve@jj:/tmp/libewf-20090506$ cd ..
steve@jj:/tmp$ ls -ld libewf*
drwxr-xr-x 15 steve steve 4096 2009-05-08 18:41 libewf-20090506
-rw-r--r-- 1 root root 2262 2009-05-08 18:42 libewf_20090506-1_amd64.changes
-rw-r--r-- 1 root root 177340 2009-05-08 18:42 libewf_20090506-1_amd64.deb
-rw-r--r-- 1 root root 511 2009-05-08 18:40 libewf_20090506-1.diff.gz
-rw-r--r-- 1 root root 826 2009-05-08 18:40 libewf_20090506-1.dsc
-rw-r--r-- 1 root root 810174 2009-05-08 18:40 libewf_20090506.orig.tar.gz
-rw-r--r-- 1 steve steve 809523 2009-05-08 18:22 libewf-beta-20090506.tar.gz
-rw-r--r-- 1 root root 222562 2009-05-08 18:42 libewf-dev_20090506-1_amd64.deb
-rw-r--r-- 1 root root 195290 2009-05-08 18:42 libewf-tools_20090506-1_amd64.deb

== Install the newly created .deb packages:
steve@jj:/tmp$ sudo dpkg -i libewf*.deb
Selecting previously deselected package libewf.
(Reading database ... 109479 files and directories currently installed.)
Unpacking libewf (from libewf_20090506-1_amd64.deb) ...
Selecting previously deselected package libewf-dev.
Unpacking libewf-dev (from libewf-dev_20090506-1_amd64.deb) ...
Selecting previously deselected package libewf-tools.
Unpacking libewf-tools (from libewf-tools_20090506-1_amd64.deb) ...
Setting up libewf (20090506-1) ...

Setting up libewf-dev (20090506-1) ...
Setting up libewf-tools (20090506-1) ...
Processing triggers for man-db ...
Processing triggers for libc6 ...
ldconfig deferred processing now taking place
steve@jj:/tmp$


== To use the mount_ewf script, need to install python-fuse:
steve@jj:/tmp$ sudo apt-get install python-fuse


== Create a mount.ewf executable in the /sbin directory and grant it "execute" permissions:
steve@jj:/tmp$ cd
steve@jj:~$ cd software/EWF/
steve@jj:~/software/EWF$ cp mount_ewf-20080513.py /sbin/mount.ewf
cp: cannot create regular file `/sbin/mount.ewf': Permission denied
steve@jj:~/software/EWF$ sudo cp mount_ewf-20080513.py /sbin/mount.ewf
steve@jj:~/software/EWF$ sudo chmod +x /sbin/mount.ewf


== And that's it - ready to go:
steve@jj:~/software/EWF$ mount.ewf
Using libewf-20090506. Tested with libewf-20080501.
Usage:
mount.ewf [options]

Note: This utility allows EWF files to be mounted as a filesystem containing a flat disk image. can be any segment of the EWF file. To be identified, all files need to be in the same directory, have the same root file name, and have the same first character of file extension. Alternatively, multiple filenames can be specified in different locations in the order to be reassembled.


ewf segment filename(s) required.
steve@jj:~/software/EWF$

Once you get the tool installed, you can mount EWF images like this:

create a mount point...mkdir /mnt/suspect
mount.ewf -o ro badguyimage.E* /mnt/suspect

The raw image will now be mounted on /mnt/suspect, and you run your TSK tools against it. Nice! The kewl thing is that you can mount your external drive as RW, then mount the image as RO. This comes in handy if you are dumping unalloc with blkls, and you only have a 80 GB HDD in your Linux box (like me)...I use external drives for everything!

SecTor 2009 - A Great Success

I just returned home from SecTor in Toronto, Ontario, Canada, and hats off to Brian Bourne and crew for putting on a great con!

With this only being the third year for the con, I honestly didn't quite know what to expect. However, after seeing what the volunteers (no paid staff) had put together, it was every bit as professional and organized as as con I have ever been to.

There were some outstanding talks this year, all of which will be available with full audio on the SecTor website under "Presentations". Some of the highlights for me were Roy Firestein's talk on "Crimeware", Jibran Ilyas and Nick Percoco's presentation of the "Malware Freakshow" (which is the same presentation that was given at DEFCON 17 this past year in Las Vegas, and Adam Laurie's (aka Major Malfunction) lunch keynote on, "The Day in the Life of a Hacker". This is not to say that all of the talks were not very very good, these are simply the ones I enjoyed the most.

If you were not able to attend this year, I highly recommend it! Very very very good con!

Babel Fish

I read an article this morning on Forensic Focus from the UK based company CY4OR detailing the emerging trend of technical data in the courtroom. The author of the article posed the questions of should there be a higher level of technical expertise required on juries in cases involving computers? After reading the article twice, and thinking about it, my answer is no (at least where the US court system in concerned), and here is why.

In the US juries are supposed to be comprised of "your peers". Now, while most folks in the US are technically aware, to think that they are "savvy" is a bit of a stretch. So finding a "peer" where most IT folks are concerned is going to be tough. Most people while some are very intelligent, are your stereo typical "end users". A good example is my pastor, Alex Himaya from the Church at Battle Creek. Alex has a MS and a Phd - a very educated and intelligent man. Well spoken, well traveled, and well respected both inside the Christian community and out. However, you put a computer in front of the man, and...well...he becomes an "end user". He can get around in Windows XP, he can do his work, but that's about it. Now that is not a slam in any way on Alex, however it shows that even people that have Phds are not any better with computers than your typical high school student (an in many cases the HS students are far better).

That puts folks like us, not just IT professionals, but computer forensic investigators, in the top 1% - 3% of computer users. We should be the upper tier of computer professionals, we should know both how the systems work and why they work that way. The technology should never be the limiting factor in our investigations. And if we run across something new or unfamiliar, we should be able to research it and figure it out in a very (like minutes to hours) short period of time.

Being a corporate investigator, over the years my customers have ranged from CEOs of fortune five companies to single location restaurant owners. I have delivered forensic reports to customers that have degrees in IT and have a pretty good understanding of what I am saying as well as people who know as much about computer science as Dunder Mifflin's Michael Scott! So what's the key to delivering a comprehensive yet understandable report? Your mom!

You think I'm joking...I'm not...your mom is the key! When you write your reports, do it in a manner that your mother could understand (if your mom is not available, any non-technical person you trust will suffice - unless of course your mom is a computer expert of some sort...then my example is blown and you will have to pick somebody else to help you with your report writing). Explain something that is technically difficult plainly and without being condescending.

For example, I have recently written a white paper on the top 10 reasons level 4 merchants are compromised. My target audience is small business owners whose primary concern is not computer security or PCI compliance, rather providing dry cleaning services, burrito plates, discount clothing, etc. In my white paper I break down technical concepts like egress filtering, secure data wiping, and port identification in a manner that my mother (no lie...I used her to help me write my paper) could easily understand. I used common terms and word pictures to illustrate technically advanced concepts clearly without making the reader feel st00p1t.

My forensic reports, like most, are broken down into sections - as I'm sure yours are (if they aren't, they should be). Doing this will enable you to address several different audiences in the same report. Your executives are likely just interested in the high level information - what happened, how, and how they can fix it. Technical or security staff members may be interesed in the specifics of what happened...ports, malware, theft, exfiltration, etc. Make sure you address each different audience ina clear and concise manner. I know I have said this before, but it won't hurt to say it again...DON'T be verbose for the sake of being verbose. Clear, concise, to the point and move on.

Now...how does this all tie together in a courtroom? Well, you are the SME. You have the technical knowledge and the jury does not. The key is not to throw technical terms and abbreviations at them to the point where they just tune you out and start wondering what's for lunch. Use common terms and analogies that they can easily understand. Jesus was a master at this! You don't have to be a Christian to appreciate how Jesus used the everyday to explain the things of Heaven to his disciples. In much the same way, you are doing the same thing. If you have to get froggy and break it down with some techie love, then fine, but make that your fall back, not your first option. Remember, your job on the stand is to get the jury to understand why the evidence you are presenting is relevant to the case, and how it proves whether something either happened to didn't happen, not to show them how smart you are.

Be the Babel Fish!

Autopilot?

A recent post on Forensic Focus got me thinking. Basically, someone asked if there was another tool like Harlan Carvey's RegRipper that could be used to validate their findings. After talking with Harlan at some length about this, we pretty much came to the same conclusion that there are a lot of folks out there who are stuck in the old school, running on auto pilot.

Let's get something straight from the get go here, I am totally for output validation when and where necessary. Since certain tools do things in certain ways, it may be important to use another tool that comes to that same result in a different way to validate that the first tool is not doing something jankity.

Case in point was the gig I had in which I was asked to determine if some office documents had been tampered with. Some tools use metadata to display chronological information while others use the OLE data. Some tools can extract chronological data without having to mount the image, others require the image to be mounted. The point here is that the tools do things in a slightly different way.

RegRipper parses registry hives. There was a funny post where a chap stated that RegRipper is not a registry viewer, so you can't mount the hives and have a "look around". While this is a true statement, I thought it was indicative of the "old school" of forensics. What are you going to look around for? Are you going to perform "Registry Analysis" with NO IDEA what you are looking for, why, or which keys do what? This is where the term "Auto Pilot" comes in. So many folks simply have blind reliance on their tools to do the work for them. They have no idea what the tool does, how it does it, and where the output in generated from. They just load, fire, and report...this tool did this...how many other tools can I get to do the same thing? Maybe by using 17 tools to take an MD5 hash, people will think I am really smart and KNOW that my MD5 hash is a good and proper MD5 hash!

What I am getting at here is that you should have a basic understanding of what the tools you are using actually do, and how they actually do that thing. I am no coder, so I could not pull apart regripper and tell you which lines to what, but I CAN read. Harlan has done a great job with documenting how regripper works and even allows you to write your own plugins! If you took about 30 mins and reviewed the documentation, you would know that regripper simply parses the data from the registry hives in a readable format. It takes the more complex keys (like those that are Rot13'd) and translates them into plain english. That's it...no smoke, no mirrors, no voodoo magic. If you want to validate your findings, get a hex editor and do it by hand.

There are a couple of takeaways here. First, understand your tools. Have at least a basic understanding of what they do and how they do it. Then you can make an educated decision if you need another tool to validate your findings. Second, don't be on auto pilot. Don't simply run a tool and then state in your report that 'Tool BLAH showed me BLAH." Instead, state what you are looking for, why you are looking for it, and THEN state what the findings were.

Remember YOU are the subject matter expert. Your case findings should be repeatable if another investigator took the same data and used the same tools. If you document your goals clearly, and the steps you took which brought you to your conclusions, you should never have a need to defend your tools.

SecTor 2009

I just found out last night that my paper on "Sniper Forensics" has been accepted to SecTor 2009! It will be a talk that shows the advantages of taking a focused approach to forensic investigations to include faster more accurate results, which means happier customers.

Also, Jibran Ilyas and Nick Percoco (fellow Trustwave teammates from the SpiderLabs) will be giving their "Malware Freakshow" presentation from DEFCON. It's awesome to have THREE speakers from Trustwave at one event like this!

If you are in CA, or just want to go to another security conference this year - I hope to see you there!

Plan the Work, Work the Plan

I have heard of investigators (and unfortunately, witnessed a few myself) that will simply go into a case without really knowing what they are looking for. They don't clarify expectations with the customer, don't think about what it is that they are trying to find, and end up just "looking for bad guy stuff". Can I just share with you what a monumentally horrible idea that is? If you don't know what it is that you are looking for, how will you ever known when you find it? This is why it is so critical to create an investigation plan BEFORE you start poking around in your data.

Creating an investigation plan is one of, if not the most important steps an investigator can take in preparation for a new case. It allows you to clearly outline what your objectives are and provides a framework for the direction of the entire case. All too often this critical step is skipped in the interest of time. What some folks don't realize is that by not having a comprehensive investigation plan, they are actually increasing the amount of time their case is likely to take.

The first question that needs to be asked at the onset of any case is, "what are my objectives". What are the goals of the case? What information does the customer want? What questions do they want answered? Once you have the specific items the customer wants to have addressed, reiterate them to ensure that there has not been a breakdown in communication somewhere.

"I am hearing that you want me to try and determine, X, Y, and Z. Is that correct?"

I know it may sound a bit juvenile, but really, everything hinges off the customer's expectations. So at the risk of misinterpreting those expectations, and failing to deliver what the customer has paid for, it is a necessary step. Ensure that both parties are "on the same sheet of music", so that when you deliver your final report you can state, "Hey...you asked me to find A, B, and C....HERE is A, B, and C".

This is where corporate investigators differ from our brethren in the law enforcement community...to a certain extent. We have a clear set of goals that our customers have paid for. They have the expectation that they will get answers to those questions. The SOW is signed, and we get to work and get them their answers in the time allotted by the contract.
In the law enforcement world, there are no timeframes and often no clear direction of what the goals are. Recently, I learned that most local, state, and federal agencies that deal with cyber-crimes are pushing out cases in anywhere from six months to three years! In that time, they may stumble upon three or four criminal activities perpetrated by the owner of the suspect system. They look under every rock, they search every crevice. They have the luxury of time (for the most part)...we do not.

Once the goals for our investigations have been established, we can apply the Alexiou Principle to further clarify our actions.

The Alexiou Principle states:
1. What question are you trying to answer?
2. What data do you need to answer that question?
3. How do you extract that data?
4. What does that data tell you?

Your questions need to be as specific as possible. You cannot simply say things like, "I want to find all signs of bad guy stuff", or "I want to find everything that this guy did wrong." Some good examples of well worded questions are:

1. How did the intruder gain access to the customer's network
2. What mechanism did the intruder use to gather customer data
3. How did the intruder get the stolen data off the customer's network

These can be answered clearly in with one sentence each.

1. The intruder gained access to the customer system by using a weak pcAnywhere password.
2. The intruder used a packet sniffer to detect and compile track data in transit.
3. The intruder used FTP to send files containing the stolen track data to his server.

There will obviously be much greater detail surrounding each question, however this is a good example of how you can be very precise in your answers. Don't take two paragraphs to say what you can say just as well in two sentences. Most customer's are not interested in verbosity, they just want to know what happened, and how.

Once you have your questions outlined, you can begin to search for the data that will provide you the answers. For example, if one of your questions is, "How did the intruder gain access to the customer's network" you are going to look in places that contain data about system access. You are NOT going to scan the machine for viruses, look for pornography, or check for rootkits. Why not? Because they have nothing to do with system access. You WOULD check in event logs, application logs (like pcAnywhere, or LogMeIn), firewall logs, ntuser.dat files, and the system and software registry hives.

With as much data that is in volatile memory, RAM dumps, and on system images, it's very easy to get overwhelmed - something referred to as "analysis paralysis". You have theories buzzing around in your head, "What if the attacker did this? What if he did that"? Don't fall victim to that kind thinking. Keep your hypothesis tied to the data. Let the data guide the direction of your case. Don't try to force the data to fit your ideas about the case.

We only have a limited time to deliver our final reports that clearly and concisely meet the customer's expectations. We do not have the luxury of time, and cannot possibly find everything that may be "wrong" with customer systems. We have been hired to answer questions...that's it. So answer them thoroughly, and in a manner that the customer can easily understand. If you stumble across something they have not asked (or paid for) then bonus...include it in the report as an additional finding, but don't go looking for them.

I have heard customers at the conclusion of a case state, "Why did you do X? I didn't ask you to do X. I asked you to do Y and Z! I want all of the money I spent on you finding X refunded to me. It was not in the contract, and I am not paying for it!" Also, I have been on the other side of that conversation in which a customer told me, "Why didn't you find Z? I wanted you to figure out Z!". To which I replied, "Hey...remember the SOW conversation we had, we outlined the goals of the investigation? Remember and you agreed to all of those items, and we put them in a contract...that you signed? You asked me to figure out A, B, and C...which I did...very clearly. If you want Z, that's fine...I will find Z, but we will need to add hours to the SOW." They didn't have any rebuttal because I MADE SURE to cover the expectations before sending over the SOW.

Develop your investigation plan based on what the customer wants. Restate their goals to them to ensure there have not been any miscommunications. Apply the Alexiou Principle to each of the goals, and get working - the clock is ticking.

Timewarp

OK...so it's been a long time since my last post...sorry...got really busy with cases.

Anyway...one of my recent cases prompted me to write this blog posting (along with some much needed prodding from Harlan). In this case, I was asked to determine the authenticity of a series of documents. Specifically, could I tell if the documents had been altered in any way so as to obfuscate their original chronological data. To determine this, I was provided an EnCase image of a removable storage device that contained the documents. Nothing more.

So instead of simply loading the image into EnCase, checking out the MAC times, and calling it a day, I decided to do a proof of concept. I needed to find out what abnormal looked like so that I would know it when I saw it.

I created an Excel spreadsheet using Microsoft Excel 2008 version 12.1.9 (090515) on an Apple MacBook Pro running MAC OSX 10.5.7, Darwin kernel 9.7.0. The Excel file was named, "pogue-test.xls" and had a MAC time of 11:31AM. I copied this file over to a Windows test box running Microsfot XP Professional v5.1 SP3 at 11:33AM, and subsequently opened it at 11:39AM on 08/07/2009.

Next, a new column was created in the spreadsheet and it was saved. As expected the Access and Write times changed. The new times showed 11:43 AM 08/07/2009.

I then used Timestomp (an anti-forensics tool commonly used to modify timestamp information) to modify just the Last Written time - pushing it back one week to Friday 07/31/09 at 5:05:05AM. As expected, when the I used the "dir /T:W " command, the new date appears, NOT the original date.

I then used Harlan Carvey's "oledmp.pl" and "wmd.pl" to display the OLE times. The results displayed from the cmd line showed the time modification, but the Perl scripts did not. This is due to the fact that the Perl scripts pull the OLE times, which are different than the file times displayed by the operating system, which use metadata.

Timestomp was used again, to modify all of the timestamps (as can be seen with the –z flag) to “Thursday 7/30/09 6:06:06AM”. When the times were listed with "dir /T and each of the time variables (:C,:W,:A), they all reflected the NEW time.

Now that the file appears to have been modified as interpreted by the OS, I again used Harlan Carvey’s Perl scripts to extract the OLE data. The scripts displayed the REAL times and not the MODIFIED times.

A second exercise was performed using TrueCrypt v6.1a to create a 10MB volume. This volume was mounted as a physical drive on a system running Windows XP v5.1 SP3, and subsequently imaged with FTK Lite v2.6.1. The resulting raw image was copied to an Ubuntu Linux 9.04 host running kernel 2.6.28-14. The Sleuth Kit (TSK) V3.0.1 was used to create a body file from the image (using the “fls” utility). The bodyfiile was then parsed with “mactime”.

The times on “pogue-test.xls” reflect the date/time when the image was created and the spoofed modification time of “Thu Jul 30 2009 06:06:06”. The file was then extracted from the image using FTK Lite v2.6.1 and saved to the local system. Again, using Harlan Carvey’s Perl scripts “oledmp.pl” and “wmd.pl” the actual MAC times were extracted as display in the exact same manner as in the first test.

The conclusion derived from this proof of concept exercise was that the operating system and subsequently EnCase (if used) would display the spoofed file times. By using forensic specific utilities (like Harlan Carvey’s Perl scripts) that extract timestamp information from the OLE of the Excel document, I was able to display the actual times.

If the files provided to me had been modified in any way, there should have been a variance between the timestamp information displayed by the operating system (metadata) and EnCase and the Perl scripts that were used.

Then I thought, "What if the document creator modified his local system time with the date/time icon from the Windows control panel? What would that look like?" So, I conducted another proof of concept exercise.

I used the date/time utility from the control panel and set the year on my system to 2020 instead of 2009. I then opened up IE and typed in some URLs, opened a cmd prompt and ran some commands, and opened a couple of programs using their desktop icons. What I opened or typed in is irrelevant, the important thing is that my actions will be tracked by the UserAssit key and the TypedURLs key in my ntuser.dat file. The last write times for each of these actions should reflect the year 2020 and not 2009.

I extracted my ntuser.dat file using FTK imager lite v2.6.1 and parsed it using Harlan Carvey's RegRipper. Low and behold, I was correct. All of the dates recorded by the registry for my actions reflected the spoofed date. ALSO, when I changed the system date back to 2009, the timedate.cpl last write time also showed the spoofed year of 2020.

So, there are a few of good takeaways from this case and proof of concept.

1. Don't rely on a single tool to give you your answers. Don't be lame and simply load your image into EnCase can call it a day. That's weak, and it's not forensics...it's called being lazy.

2. If you don't know what "abnormal" is going to look like, figure it out. Conduct some proof of concept exercises so that you at least have some idea of what you are looking for.

3. Make sure you inform the customer of what you were able to do, and what you were not able to do. If you were not able to perform certain actions, tell them why, and request that data. In my case, I requested an image of the original system so that I could look for additional data points in the registry that would support chronological modifications.

Good stuff! Sorry again for the break in writing...I will try not to lapse like that again!