Windows Forensics Training PDF

UNIT 2: WINDOWS FORENSICS DON CAEIRO UNDERSTANDING FILE SYSTEMS UNDERSTANDING FILE SYSTEMS File system Gives OS a road map to data on a disk Type of file system an OS uses determines how data is stored on the disk A file system is usually directly related to an OS When you need...

UNIT 2: WINDOWS FORENSICS DON CAEIRO UNDERSTANDING FILE SYSTEMS UNDERSTANDING FILE SYSTEMS File system Gives OS a road map to data on a disk Type of file system an OS uses determines how data is stored on the disk A file system is usually directly related to an OS When you need to access a suspect’s computer to acquire or inspect data You should be familiar with the computer’s platform UNDERSTANDING DISK DRIVES Disk drives are made up of one or more platters coated with magnetic material Disk drive components Geometry Head Tracks Cylinders Sectors Holds 512 bytes, you cannot read or write anything less than a sector UNDERSTANDING DISK DRIVES (CONTINUED) Properties handled at the drive’s hardware or firmware level Zoned bit recording (ZBR) Track density Areal density Head and cylinder skew EXPLORING MICROSOFT FILE STRUCTURES EXPLORING MICROSOFT FILE STRUCTURES In Microsoft file structures, sectors are grouped to form clusters Storage allocation units of one or more sectors Clusters are typically 512, 1024, 2048, 4096, or more bytes each Combining sectors minimizes the overhead of writing or reading files to a disk EXPLORING MICROSOFT FILE STRUCTURES (CONTINUED) Clusters are numbered sequentially starting at 2 First sector of all disks contains a system area, the boot record, and a file structure database OS assigns these cluster numbers, called logical addresses Sector numbers are called physical addresses Clusters and their addresses are specific to a logical disk drive, which is a disk partition DISK PARTITIONS A partition is a logical drive FAT16 does not recognize disks larger than 2 GB Large disks have to be partitioned Hidden partitions or voids Large unused gaps between partitions on a disk Partition gap Unused space between partitions DISK PARTITIONS (CONTINUED) Disk editor utility can alter information in partition table To hide a partition Can examine a partition’s physical level with a disk editor: HxD, Norton DiskEdit, WinHex, or Hex Workshop Analyze the key hexadecimal codes the OS uses to identify and maintain the file system MASTER BOOT RECORD STRUCTURE PARTITION TABLE STRUCTURE PARTITION MARK AT START OF VOLUME Start HxD, Extras, Open Disk NTFS FAT32 BMP FILE IN HXD Start HxD, File, Open BM at start indicates a BMP file WORD DOC FILE IN HXD Start HxD, File, Open Word 2003 Format uses these 7 bytes.docx format is actually a Zip archive MASTER BOOT RECORD On Windows and DOS computer systems Boot disk contains a file called the Master Boot Record (MBR) MBR stores information about partitions on a disk and their locations, size, and other important items Several software products can modify the MBR, such as PartitionMagic’s Boot Magic EXAMINING FAT DISKS File Allocation Table (FAT) File structure database that Microsoft originally designed for floppy disks Used before Windows NT and 2000 FAT database is typically written to a disk’s outermost track and contains: Filenames, directory names, date and time stamps, the starting cluster number, and file attributes FAT versions FAT12, FAT16, FAT32, FATX (for Xbox), and VFAT FAT VERSIONS FAT12—for floppy disks, max size 16 MB FAT16—allows hard disk sizes up to 2 GB FAT32— allows hard disk sizes up to 2 TB  EXAMINING FAT DISKS (CONTINUED) Cluster sizes vary according to the hard disk size and file system This table is for FAT-16 EXAMINING FAT DISKS (CONTINUED) When you run out of room for an allocated cluster OS allocates another cluster for your file, which creates more slack space on the disk As files grow and require more disk space, assigned clusters are chained together The chain can be broken or fragmented PRODISCOVER SHOWING CLUSTER CHAIN EXAMINING FAT DISKS (CONTINUED) When the OS stores data in a FAT file system, it assigns a starting cluster position to a file Data for the file is written to the first sector of the first assigned cluster When this first assigned cluster is filled and runs out of room FAT assigns the next available cluster to the file If the next available cluster isn’t contiguous to the current cluster File becomes fragmented DELETING FAT FILES In Microsoft OSs, when a file is deleted Directory entry is marked as a deleted file With the HEX E5 (σ) character replacing the first letter of the filename FAT chain for that file is set to 0 Data in the file remains on the disk drive Area of the disk where the deleted file resides becomes unallocated disk space Available to receive new data from newly created files or other files needing more space EXAMINING NTFS DISKS New Technology File System (NTFS) Introduced with Windows NT Recommended file system for Windows 200 Pro, XP, and later versions through Windows 7 at least Improvements over FAT file systems NTFS provides more information about a file NTFS gives more control over files and folders NTFS was Microsoft’s move toward a journaling file system EXAMINING NTFS DISKS (CONTINUED) In NTFS, everything written to the disk is considered a file On an NTFS disk First data set is the Partition Boot Sector Next is Master File Table (MFT) NTFS results in much less file slack space Clusters are smaller for smaller disk drives NTFS also uses Unicode An international data format EXAMINING NTFS DISKS (CONTINUED) NTFS FILE SYSTEM MFT contains information about all files on the disk Including the system files the OS uses In the MFT, the first 15 records are reserved for system files Records in the MFT are called metadata NTFS FILE SYSTEM (CONTINUED) NTFS FILE SYSTEM (CONTINUED) MFT AND FILE ATTRIBUTES In the NTFS MFT All files and folders are stored in separate records of 1024 bytes each Each record contains file or folder information This information is divided into record fields containing metadata A record field is referred to as an attribute ID File or folder information is typically stored in one of two ways in an MFT record: Resident and nonresident RESIDENT FILE IN A MFT RECORD MFT AND FILE ATTRIBUTES (CONTINUED) When a disk is created as an NTFS file structure OS assigns logical clusters to the entire disk partition These assigned clusters are called logical cluster numbers (LCNs) Become the addresses that allow the MFT to link to nonresident files on the disk’s partition NTFS COMPRESSED FILES NTFS provides compression similar to FAT DriveSpace 3 Under NTFS, files, folders, or entire volumes can be compressed Most computer forensics tools can uncompress and analyze compressed Windows data NTFS ENCRYPTING FILE SYSTEM (EFS) Encrypting File System (EFS) Introduced with Windows 2000 Implements a public key and private key method of encrypting files, folders, or disk volumes When EFS is used in Windows 2000 A recovery certificate is generated and sent to the local Windows administrator account Users can apply EFS to files stored on their local workstations or a remote server DELETING NTFS FILES When a file is deleted in Windows XP, 2000, or NT The OS renames it and moves it to the Recycle Bin Can use the Del (delete) MS-DOS command Eliminates the file from the MFT listing in the same way FAT does UNDERSTANDING THE WINDOWS REGISTRY  UNDERSTANDING THE WINDOWS REGISTRY Registry A database that stores hardware and software configuration information, network connections, user preferences, and setup information For investigative purposes, the Registry can contain valuable evidence To view the Registry, you can use: Regedit (Registry Editor) program for Windows 9x systems Regedt32 for Windows 2000 and XP EXPLORING THE ORGANIZATION OF THE WINDOWS REGISTRY (CONTINUED) EXPLORING THE ORGANIZATION OF THE WINDOWS REGISTRY (CONTINUED) UNDERSTANDING MICROSOFT STARTUP TASKS UNDERSTANDING MICROSOFT STARTUP TASKS Learn what files are accessed when Windows starts This information helps you determine when a suspect’s computer was last accessed Important with computers that might have been used after an incident was reported STARTUP IN WINDOWS NT AND LATER All Windows NT computers perform the following steps when the computer is turned on: Power-on self test (POST) Initial startup Boot loader Hardware detection and configuration Kernel loading User logon STARTUP PROCESS FOR WINDOWS VISTA Uses the new Extensible Firmware Interface ( EFI) as well as the older BIOS sys-tem. NT Loader (NTLDR) has been replaced by three boot utilities Bootmgr.exe—displays list of operating systems Winload.exe—loads kernel, HAL, and drivers Winresume.exe—restarts Vista after hibernation STARTUP IN WINDOWS 9X/ME (CONTINUED) The system files used by Windows 9x have their origin in MS-DOS 6.22 Io.sys communicates between a computer’s BIOS, the hardware, and the OS kernel If F8 is pressed during startup, Io.sys loads the Windows Startup menu Msdos.sys is a hidden text file containing startup options for Windows 9x Command.com provides a command prompt when booting to MS-DOS mode (DPMI) UNDERSTANDING MS- DOS STARTUP TASKS UNDERSTANDING MS-DOS STARTUP TASKS Two files are used to configure MS-DOS at startup: Config.sys A text file containing commands that typically run only at system startup to enhance the computer’s DOS configuration Autoexec.bat A batch file containing customized settings for MS-DOS that runs automatically Io.sys is the first file loaded after the ROM bootstrap loader finds the disk drive UNDERSTANDING MS-DOS STARTUP TASKS (CONTINUED) Msdos.sys is the second program to load into RAM immediately after Io.sys It looks for the Config.sys file to configure device drivers and other settings Msdos.sys then loads Command.com As the loading of Command.com nears completion, Msdos.sys looks for and loads Autoexec.bat OTHER DISK OPERATING SYSTEMS Control Program for Microprocessors (CP/M) First nonspecific microcomputer OS Created by Digital Research in 1970 8-inch floppy drives; no support for hard drives Digital Research Disk Operating System (DR-DOS) Developed in 1988 to compete with MS-DOS Used FAT12 and FAT16 and had a richer command environment SRUM SYSTEM RESOURCE USER MANAGEMENT (SRUM) User management is about interfacing humans to computers. This brings to light a number of issues: Accounting: Registering new users and deleting old ones. Comfort and convenience. Support services. Ethical issues. Trust management and security.  SYSTEM ADMINISTRATION DUTIES Analyse system logs and identify potential issues that need attention. Introduce and integrate new technologies. Performing backups. Updating OSs and applying patches and configuration changes. Installing and configuring new hardware and software. Configure, monitor and maintain: – Email applications – Virus protection software – Etc  forensic analysis of a data set that spans multiple drives.