The world of digital forensics - 2/2
The order volatility is basically listing the order of steps to be performed, like what do you go to first, then what do you go to, and then what you do after that.
In the list, the first step is to check:
1. Machine memory
All the processes and services that are running on the computer are important, but there's a lot of other stuff in there too as well, for example, caches. Even CPU caches can be critical, the MAC addresses etc. So, dealing with memory is very important. There are tons of great programs; these programs gather everything from memory and dump it to a file, out there that are great at grabbing and dumping memory.
2. Data on the disk itself
Data not only on the disks, but also on optical media or flash drive must be taken into consideration.
When a system is up and running there's a lot of data on that disk that will probably disappear like cache files when the system's shut down.
There could be temporary files that are very important, now in this type of situation there literally hundreds of programs that are out there and designed to grab the data. All these programs are designed to work in some form of what we call write block. If you're looking for simple software even a program like Linux' does a great job of doing a detailed grab of the entire image.
The next in the list is
3. Remotely logged data
A lot of times there are two connections, lets say, between local machine and server, that gets established. So, if someone's doing something on a website there might be logs on that remote web site. If somebody is doing something on a file server, there might be something on the file server in terms of when did, they access it or something like that that can be very important for you to grab. Logs tend to last a good amount of time, but it's important for you to grab it as quickly as possible.
Backups are wonderful tool for looking for trends. Like someone has done this multiple time in the past, we had this exact situation take place five times in the last year.
However, backups even though they have very low volatility it can often take a while to grab all that data.
Let’s now discuss about the process of gathering this data.
This is not an order but basically a checklist of issues you should be thinking about when performing digital forensics.
1. Capture the system image. You would be hard pressed to come up with a scenario where you're not grabbing the system image from whatever system is in question. What tool you use is up to you,but keep in mind write blocking tools are often very common for this type of situation.
2. Grab network traffic and logs. Not only will the be some logs on the system itself but here's the opportunity to go over to the domain controller, to go over to what other servers that the system might be accessing and get an idea of where this person has been and what they're doing.
3. Capture video. Videotape physically the workstation, everything laying around it so that it's well-documented, capturing audio as well can mean if you're finding media, go ahead and capture all that too which would be normally part of the system image itself. Last you might want to look around for security cameras. Are there any other cameras that are part of a broader physical security system? that might be appropriate to this situation? Anytime you're dealing with video always record a time offset. Make sure people know what they're seeing and when it happened.
4. Take hashes. Hash every file, hash every image. Most good forensics tools have built in auto hashing functions, but the hash is your ultimate proof to show the integrity of any single piece of data that you've handled.
5. Take screenshots. When you walk up grab a screen capture, look at what's happening, and be sure to capture all these, and again, be sure to record date and time.
6. Interview witnesses. Anybody who's been nearby. Anybody who a communication was taking place. Get these interviews done quickly, get the documentation, contact information, and their job function within that organization so that, if, necessary, law enforcement can speak to them.
7. Track the man hours. Conducting forensics cost money and time. For example, you might have budget issues in terms of how hard your organization is going to be defending an issue or you might have an insurance issue where your organization is going to be paid back for your hard work. The bottom line is every moment you're working, you're tracking those man hours.
The whole world of digital forensics is fascinating. And brings very good career options.