SANS Digital Forensics and Incident Response Blog: Category - Evidence Analysis

FreeBSD Computer Forensic Tips & Tricks

Hal Pomeranz, Deer Run Associates

While Linux seems to have captured much of the mind-share for Unix-like operating systems, the fact is that there are an awful lot of BSD machines out there, particularly in web-hosting and other Internet-facing environments. So you're likely to run into one of these systems during an incident response or digital forensics investigation at some point. If you've only ever analyzed Linux systems, you may encounter a few bumps in the road when you start looking at your first BSD system. In an effort to smooth out some of those potholes, I'm going to demo a few useful techniques using a sample FreeBSD image I created.

BSD Disk Labels

Let's suppose somebody just handed you a raw disk image that they took from a FreeBSD machine. Not being Unix savvy, all they can do is

...


Examining Windows Mobile Devices Using File System Forensic Tools

Windows Mobile file systems have similarities with other Microsoft operating systems that make for an easy transition into mobile device forensics for anyone who has performed forensic examinations of Windows computer systems. As with a desktop or laptop computer, Windows Mobile devices retain substantial information about user activities that can be relevant in a digital investigation involving Web browsing, user created files, and Windows registry entries.

Windows Mobile uses a variation of the FAT file system called the Transaction-safe FAT (TFAT) file system, which has some recovery features in the event of a sudden device shutdown. Here is the volume information of a memory dump from a Windows Mobile device, showing that it is FAT.

$ fsstat SamsungBlackjack.bin

FILE SYSTEM INFORMATION
--------------------------------------------
File System Type: FAT16
OEM Name:

... Continue reading Examining Windows Mobile Devices Using File System Forensic Tools


It's the little things (Part One)

For forensic analysts working in Windows environments, .lnk shortcut files and the thumbprint caches are valuable sources for details about missing data.

Individuals wanting to hide their activities may flush their browser cache, Temp files, use, and even wipe the drive free space. However, they may forget these two minor "tidbits". These can show detail, indicate actions and associated history. Be Warned, I have found Windows machines having thousands of .lnk files on a "scrubbed PC."

The shortcut (.lnk) file is an amazing mine of information for such a small file. This PDF (See Link) is an invaluable source describing the details of the shortcut .lnk. The shortcut file name format is usually name.ext.lnk There may be multiple .lnk files created for one file depending upon the type.

XP stores the .lnk files for the Word 2007 Document Brains.docx in:


Fun with FIFOs (Part II): Output Splitting

Hal Pomeranz, Deer Run Associates

Several months ago now, I wrote up a little article on using FIFOs to trick the script command into writing output over the network. But there are other neat hacks you can do with FIFOs, and I want to show you one right now that can save you lots of time.

Suppose you had a disk image and you wanted to pull out both the ASCII and Unicode strings from a specific partition. The classic approach is to read the partition twice- once to gather the ASCII strings and once to pull out the Unicode. But on a large partition, reading the image even once can take a huge amount of time. The good news is we can use some Unix FIFO magic along with the frequently overlooked tee

...


Using Image Offsets

Hal Pomeranz, Deer Run Associates

One of the basic techniques we teach in SANS Forensic classes is "carving" out partition images from complete raw disk images. All it takes is a little facility with mmls and dd. Here's a quick example of carving an NTFS partition out of a disk image to show you what I mean:

$ mmls -t dos drive-image.dd
DOS Partition Table
Offset Sector: 0
Units are in 512-byte sectors

Slot Start End Length Description
00: ----- 0000000000 0000000000 0000000001 Primary Table (#0)
01: ----- 0000000001 0000000062 0000000062 Unallocated
02: 00:00 0000000063 0000064259 0000064197 DOS FAT12 (0x01)
03: 00:01 0000064260 0000273104 0000208845 DOS Extended (0x05)
04:

...