Alternative Methods of Analysis

Do I need to say it again? The age of Nintendo Forensics is gone, long past.

Acquiring a system is no longer as simple as removing the hard drive, hooking it up to a write blocker, and imaging it. Storage capacity is increasing, devices capable of storing data are diversifying and becoming more numerous (along with the data formats)...all of which are becoming more ubiquitous and common-place. As the sophistication and complexity of devices and operating systems increases, the solution to the issue of backlogs due to examinations requiring additional resources is training and education.

Training and education lead to greater subject-matter knowledge, allowing the investigator to ask better questions, and perhaps even make better requests for assistance. Having a better understanding of what is available to you and where to go to look leads to better data collection, and more thorough and efficient examinations. It also leads to solutions that might not be readily apparent to those that follow the "point and click execution" methodology.

Take this article from Police Chief Magazine, for example. 1stSgt Cohen goes so far as to specifically mention the collection of volatile data and the contents of RAM. IMHO, this is a HUGE step in the right direction. In this instance, a law enforcement officer is publicly recognizing the importance of volatile data in an investigation.

It's also clear from the article that training and education has led to the use of a "computer forensics field triage", which simply exemplifies the need for growth in this area. It's also clear from the article that a partnership between law enforcement, the NW3C and Purdue University has benefited all parties. It would appear that at some point in the game, the LEs were able to identify what they needed, and were able to request the necessary assistance from Purdue and NW3C...something known in consulting circles as "requirements analysis". At some point, the cops understood the importance of volatile memory, and thought, "we need this...now, how do we collect it in the proper manner?"

So what does this have to do with alternative methods of analysis? An increase in knowledge allows you to seek out alternative methods for your investigation.

For example, take the Trojan Defense. The "purist" approach to computer forensics...remove the hard drive from the system, acquire an image, and look for files...appears to have been less than successful, in at least one case in 2003. The effect of this decision may have set the stage for other similar decisions. So, let's say you've examined the image, searched for files, even mounted the image as a file system and hit it with multiple AV, anti-spyware, and hash-comparison, and still haven't found anything. Then lets assume you had collected volatile data...active process list, network connections, port-to-process mapping, etc. Parsing that data, wouldn't the case have been a bit more iron-clad? You'd be able to show that at the time the system was acquired, here are the processes that were running (along with their command line options, etc.), installed modules, network connections, etc.

At that point, the argument may have been that the Trojan included a rootkit component that was memory-resident and never wrote to the disk. Okay, so let's say that instead of running individual comments to collect specific elements of memory (or, better yet, before doing that...), you'd grabbed the contents of RAM? Tools for parsing the contents of RAM do not need to employ the MS API to do so, and can even locate an exited or unlinked process, and then extract the executable image file for that process from the RAM dump.

What if the issue had occurred in an environment with traffic monitoring...firewall, IDS and IPS logs may have come into play, not to mention traffic captures gathered by an alert admin or a highly-trained IR team? Then you'd have even more data to correlate...filter the network traffic based on the IP address of the system, isolate that traffic, etc.

The more you know about something, the better. The more you know about your car, for example, the better you are able to describe the issue to a mechanic. With even more knowledge, you may even be able to diagnose the issue and be able to provide something more descriptive than "it doesn't work". The same thing applies to IR, as well as to forensic analysis...greater knowledge leads to better response and collection, which leads to more thorough and efficient analysis.

So how do we get there? Well, someone figured it out, and joined forces with Purdue and NW3C. Another way to do this is through online collaboration, forums, etc.

IMHO

I received some questions from readers and I thought
that I'd take a crack at them...

With consumer and commerical hard drives getting larger
and larger (soon there will be a consumer-level 1TB HD)
what effect will the sheer volume of information have
on the forensics community in general, and the 
open-source forensics community in specific? Does the
future include more automated tools? Distributed forensic
examinations? Will the open-source forensic 
community be able to keep up with the commercial tools?

For the most part, this appears to be two separate
questions, but I'll treat them as pretty much the same
one.

This is nothing new...the challenge of increasing volumes
has affected the forenic community since...well...since
there was storage.  Capacities have always increased...such
is the nature of a consumer market.  So what's the answer?
Well, in a nutshell...the Age of Nintendo Forensics is
dead.  What I mean by that is that new techniques,
processes and methodologies need to be employed to
meet these challenges.  We can no longer rely on
simply pushing a button...we have to understand
what it is we're looking for, and where to
look for it.

Notice I didn't say "developed".  Rather, I said "employed".
Yes, it was my intention to imply that these techniques are
already available, and actually used by a number of
practioners.  However, the vast majority of the digital
forensics community appears to rely on the traditional
approach to computer forensics analysis, which can be
likened to killing the victim of a crime and performing
an autopsy to see what happened.

Live analysis techniques need to be employed more often.
Many traditionalists say that "I won't use these
techniques until they've been proved in court."
Well, consider this...at one point, computer forensics
wasn't used in court, and had to be proven.

Suffice to say, computing technology grows in complexity
...this applies to the hardware, as well as the software.
Accordingly, forensic techniques need to keep pace.
The traditional techniques are still usable...I'm not
saying that they aren't...but practitioners can no longer
learn one thing and hope to stay in business as complexity
and change surrounds them.  We need to grow in knowledge
and understanding in order to keep up.  This includes
Locard's Exchange Principle, as well as understanding
what actions or conditions lead to the creation and
modification of certain artifacts...from that, we
understand that the absence of an artifact is in
itself an artifact.

Some of the challenges introduced by Windows Vista
include extracting live memory and (presumably) an
increase in use of EFS by consumers. How can these 
challeges best be addressed by the forensics community?

The challenge of extracting live memory has been an
issue since Windows 2003 SP1, when user-mode access
to the \\.\PhysicalMemory object was restricted.
However, has it really been a challenge, per se?
How many folks have obtained memory dumps, and of
those, how have they been used?  It isn't as if
the vast majority of the community has been using
physical memory as a source of evidence and
presented that in court.

That being said, these challenges will be addressed
by a small portion of the forensics community. 
That core group (and it may be dispersed) have
developed processes and methodologies, as well as
documentation, that they will use, and even
publish.  However, it may be a while before the
rest of the "community" of forensic practitioners
catches on and begins using these on a regular
basis.

Since Vista was specifically asked about, I'll
throw this out there...there is a Registry value
called NtfsDisableLastAccessUpdate, and yes, it
does just exactly what as it sounds.  If this
value is set to "1", then the operating system
will not update last access times on files. 
From NT through 2003, this has been a setting
that was disabled by default, and recommended
to be set for high-volume file servers in order
to increase performance.  However, on Vista,
this functionality is enabled by default.  What
this means is that examiners are going to have
to use other techniques for determining timelines
of activity, etc., and that may even require
Registry analysis.

Do you think there are ethical challenges
specific to forensic examiners or 
incident handlers? What do you think is
the most effective method of oversight in 
small offices where there may only be one
examiner? Would you say that strong personal
ethics are more important than technical
skill for an examiner/incident handler?

I would suggest that ethics is not something
that is restricted to forensic examiners alone,
but just as important in all fields.  I think
that in any field, a wake-up call comes when
someone falls into that "who are you to
question me" trap and then gets caught. 
I also think that is an important evolution
and good for the community at large. 
In this kind of work it is important to
remain humble and to constantly keep checking
ourselves.  There's nothing wrong with going to
someone else and asking, hey, did I do enough
here, or is this telling me what I think it's
telling me?  Overall, I think that builds trust,
and strengthens the individuals.

Thoughts?  Comments?  Email me, or leave a comment...