Tools:Memory Imaging

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The physical memory of computers can be imaged and analyzed using a variety of tools. Because the procedure for accessing physical memory varies between operating systems, these tools are listed by operating system. Usually memory images are used as part of memory analysis.

One of the most vexing problems for memory imaging is verifying that the data has been imaged correctly. Because the procedure cannot be repeated (i.e. the memory changes during the process), it is impossible to do the acquisition again and compare the results. At this time the structures involved are not known well enough to determine the integrity of the image.

Memory Imaging Techniques

Crash Dumps
When configured to create a full memory dump, Windows operating systems will automatically save an image of physical memory when a bugcheck (aka blue screen or kernel panic) occurs. Andreas Schuster has a blog post describing this technique.
LiveKd Dumps
The Sysinternals tool LiveKd can be used to create an image of physical memory on a live machine in crash dump format. Once livekd is started, use the command ".dump -f [output file]"
Hibernation Files
Windows 98, 2000, XP, 2003, and Vista support a feature called hibernation that saves the machine's state to the disk when the computer is powered off. When the machine is turned on again, the state is restored and the user can return to the exact point where they left off. The machine's state, including a compressed image of physical memory, is written to the disk on the system drive, usually C:, as hiberfil.sys. This file can be parsed and decompressed to obtain the memory image. Once hiberfil.sys has been obtained, Sandman can be used to convert it to a dd image.
Mac OS X very kindly creates a file called /var/vm/sleepimage on any laptop that is suspended. This file is NOT erased when the machine starts up. It is unencrypted even if the user turns on File Vault and enables Secure Virtual Memory. [1].
It is possible for Firewire or IEEE1394 devices to directly access the memory of a computer. Using this capability has been suggested as a method for acquiring memory images for forensic analysis. Unfortunately, the method is not safe enough to be widely used yet. There are some published papers and tools, listed below, but they are not yet forensically sound. These tools do not work with all Firewire controllers and on other can cause system crashes. The technology holds promise for future development, in general should be avoided for now.
At CanSec West 05, Michael Becher, Maximillian Dornseif, and Christian N. Klein discussed an exploit which uses DMA to read arbitrary memory locations of a firewire-enabled system. The paper lists more details. The exploit is run on an iPod running Linux. This can be used to grab screen contents.
This technique has been turned into a tool that you can download from:

Memory Imaging Tools

Windows Hardware

Tribble PCI Card

Windows Software

winen.exe (Guidance Software - included with Encase 6.11 and higher)
included on Helix 2.0
included on Helix 2.0
Mdd (Memory DD) (ManTech)
included on Helix 2.0
F-Response with FTK imager, dd, Encase, WinHex, etc
Beta 2.03 provides remote access to memory that can be acquired using practically any standard imaging tool
Can capture and analyze memory. Supports reading dumps (raw/dd format) from other tools.
On Microsoft Windows systems, dd can be used by an Administrator user to image memory using the \Device\Physicalmemory object. Userland access to this object is denied starting in Windows 2003 Service Pack 1 and Windows Vista.
Windows Memory Forensic Toolkit (WMFT)
Fastdump and Fastdump Pro
Fastdump (free with registration) Can acquire physical memory on Windows 2000 through Windows XP 32 bit but not Windows 2003 or Vista.
Fastdump Pro Can acquire physical memory on all Windows operating systems 32 and 64 bit and also on systems with more than 4GB of RAM. The Fastdump Pro memory footprint is larger than regular fastdump footprint because there is a lot more functionality built in to the Pro version. Fastdump Pro takes about 650kb of memory to run on Vista Ultimate Sp1.


On Unix systems, the program dd can be used to capture the contents of physical memory using a device file (e.g. /dev/mem and /dev/kmem).
Idetect (Linux)

External Links

Windows Memory Analysis (Sample Chapter)