Thursday, July 18, 2013

Daily Blog #25: Go Bag Part 4 - Advanced Persistent Problem Child

Hello Reader!,
       It's Thursday, the week goes fast when your busy. I hope these daily blogs are interesting to you and helping your week go faster as well. I'm continuing the imaging scenarios today as enter the realm of the 'oh not this' level of imaging. We are doing lots of research here at G-C as our cases continue to get more complex and we see more Windows 7 systems and their artifacts get produced in cases. I'm hoping that as these results are validated we can put out some more Saturday reading papers on USN journal analysis, it's not as simple as it appears!

The system is in sleep mode The system has been brought to me and it was thought to be powered off, but really the user just closed the lid on the laptop and it went to sleep. 

This is a pretty common scenario and you have four options at this point in order of time required (least to most):


  1. You have to have this device imaged and returned ASAP and you have no reason to believe that the contents of memory will be relevant as the event you are investigating occurred in the past. In this case your best course of action may be to pull the battery and image the drive offline. 
  2. You have to have the device image and returned ASAP, but the user is willing to provide their password. In this scenario you would do a live image of the system's memory to your external drive and then since you've already created the artifacts relating to the memory capture and storage connection (whether network or external storage) so you might as well do a live forensic image as well. 
  3. You have to have the device image but you can return it later that day or the next. This is a good middle scenario and I'll explain why. If you have enough time to let the battery power run out the system will on its own going into hibernation causing it to write the contents of memory to disk and allowing you to get a copy of both the disk and the contents of RAM without having to introduce any artifacts from your software/hardware. If you are worried about overwriting the old hiberfil.sys know that for Windows Vista and 7 systems it should be in the volume shadows as well.
  4. You have to have the device image, its Windows XP or before and you don't have time to wait for it to suspend. At this point if your lucky they have a firewire port on their computer which will let you directly access the contents of RAM without authenticating to the system, your device will show up in sbp2 store though in the system registry and its plugin will be recorded in the setup logs. 

The system is connected to a SAN - You've been taken to the system and see a fiber cable coming out of the back of it, you realize its likely connected to a SAN


Termonology to kow here:

HBA - Host bus adapter - This is your fiber card interface to the SAN like a network card
SAN - Storage Array Network - This is a large embedded system that can contain 100s of hard drives and present slices of them to systems as local storage
LUN - Logical Unit Number - How the disk is identified between the SAN and the system that mounts it
Fiber port - The physical port on the fiber hub your SAN and systems are connected to

Things to know before even starting:
  • Pulling a drive from a SAN will result in the SAN discarding those drives 
  • You do not know which drives in a SAN your data is written on typically
  • I am not aware of a forensic tool that has support for any SANS proprietary algorithm for storing data across drives and even if you where to image the disks with the SAN offline you would not likely be able to reassemble the file system
  • You need to know the following 
    • The type of HBA in the system (single mode or multimode)
    • The LUN the HBA is connecting to
    • The port you are plugged into
    • If there are any ports open
Ok now that we have that covered this is how you deal with it. You have two options depending on if you can take the system offline.
  1. You can take the system offline
If you can take the system offline then you can reboot it off of your forensically sound boot CD, I keep saying Linux but it could WinFE as well. I have more experience with Linux boot CD/DVDs though. If your bootable distribution has support for the fiber card HBA then you should have the disk presented to you at boot time as another physical drive you can image. This works because SAN security is typically set for the port the device is plugged into rather than any type of credential, so if you can access it from the same port you should be presented with the disk. 

    2.  You can't take the system offline

You have two options here. 

    A. Make a live image, this is the simplest method. The OS will already have the fiber card drivers loaded and the physical disk will be available to you for imaging.

    B. If you can't make a live image and you can't shut it down this is what you have to do to get at the SAN disk.


  1. Get the SAN administrator to allocate a port you can plug another computer with a compatible HBA 
  2. Get the SAN administrator to provide access to the LUN your target system is accessing to your new port
  3. Boot your system off a Linux winfe forensically sound system with the HBA connected  you should see the physical disk presented to you
  4. Realize that you need to still treat this as volatile evidence, the original system is still accessing/changing this disk and the only write protection you have is your operating system correctly treating the SAN disk as read only.
  5. Image the disk and shutdown, making sure never to mount the disk read/write and if its a journaled file system (ext3/4) make sure that you mount it read only as a non-journaled variant (ext2) if you simply have to mount it and extract data from the live system. 

    I know point 5 may seem confusing especially on the read only exception there. The read only flag in your Linux mount applies to the data but the underlying journal file system may still be updated in ext3/4 on mounting it even if you tell it to mount read only. Be aware of this as you may cause two competing journal operations to collide and that wouldn't be good!

    So there you go, all my SAN nightmares boiled down to a how to guide. I hope this helps you because they are not going away. Tomorrow we will talk about NAS and embedded systems