Utilizing Regent University library and Internet resources, research what can and cannot be retrieved from operating systems. For example, is a deleted file retrievable? Share y

Utilizing Regent University library and Internet resources, research what can and cannot be retrieved from operating systems. For example, is a deleted file retrievable? Share your findings.

Your response(s) should comply with the formatting, content, and word count guidelines, along with the style manual requirements, indicated in the syllabus. 300-400 wrds

 https://libguides.regent.edu/az/databases 

Ch5.pptx


Ch6.pptx

Guide to Computer Forensics and Investigations Sixth Edition Chapter 5

Working with Windows and CLI Systems

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Guide to Computer Forensics and Investigations Sixth Edition

Chapter 5

Working with Windows and CLI Systems

1

Explain the purpose and structure of file systems

Describe Microsoft file structures

Explain the structure of NTFS disks

List some options for decrypting drives encrypted with whole disk encryption

Explain how the Windows Registry works

Describe Microsoft startup tasks

Explain the purpose of a virtual machine

Objectives

2

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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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

When you need to access a suspect’s computer to acquire or inspect data

You should be familiar with both the computer’s OS and file systems

Understanding File Systems

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

3

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Complementary Metal Oxide Semiconductor (CMOS)

Computer stores system configuration and date and time information in the CMOS

When power to the system is off

Basic Input/Output System (BIOS) or Extensible Firmware Interface (EFI)

Contains programs that perform input and output at the hardware level

Understanding the Boot Sequence (1 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

4

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Bootstrap process

Contained in ROM, tells the computer how to proceed

Displays the key or keys you press to open the CMOS setup screen

CMOS should be modified to boot from a forensic floppy disk or CD

Understanding the Boot Sequence (2 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Understanding the Boot Sequence (3 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

6

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Disk drives are made up of one or more platters coated with magnetic material

Disk drive components

Geometry

Head

Tracks

Cylinders

Sectors

Understanding Disk Drives (1 of 4)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Understanding Disk Drives (2 of 4)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Understanding Disk Drives (3 of 4)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

9

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Properties handled at the drive’s hardware or firmware level

Zone bit recording (ZBR)

Track density

Areal density

Head and cylinder skew

Understanding Disk Drives (4 of 4)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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All flash memory devices have a feature called wear-leveling

An internal firmware feature used in solid-state drives that ensures even wear of read/writes for all memory cells

When dealing with solid-state devices, making a full forensic copy as soon as possible is crucial

In case you need to recover data from unallocated disk space

Solid-State Storage Devices

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

11

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In Microsoft file structures, sectors are grouped to form clusters

Storage allocation units of one or more sectors

Clusters range from 512 bytes up to 32,000 bytes each

Combining sectors minimizes the overhead of writing or reading files to a disk

Exploring Microsoft File Structures (1 of 2)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

12

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Clusters are numbered sequentially starting at 0 in NTFS and 2 in FAT

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

Exploring Microsoft File Structures (2 of 2)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

13

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A partition is a logical drive

Windows OSs can have three primary partitions followed by an extended partition that can contain one or more logical drives

Hidden partitions or voids

Large unused gaps between partitions on a disk

Partition gap

Unused space between partitions

Disk Partitions (1 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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The partition table is in the Master Boot Record (MBR)

Located at sector 0 of the disk drive

In a hexadecimal editor, such as WinHex, you can find the first partition at offset 0x1BE

The file system’s hexadecimal code is offset 3 bytes from 0x1BE for the first partition

Disk Partitions (2 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Disk Partitions (3 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

16

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File Allocation Table (FAT)

File structure database that Microsoft originally designed for floppy disks

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

Three current FAT versions

FAT16, FAT32, and exFAT (used for mobile personal storage devices)

Cluster sizes vary according to the hard disk size and file system

Examining FAT Disks (1 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Examining FAT Disks (2 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Microsoft OSs allocate disk space for files by clusters

Results in drive slack

Unused space in a cluster between the end of an active file’s content and the end of the cluster

Drive slack includes:

RAM slack and file slack

An unintentional side effect of FAT16 allowing large clusters was that it reduced fragmentation

As cluster size increased

Examining FAT Disks (3 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Examining FAT Disks (4 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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When you run out of room for an allocated cluster

OS allocates another cluster for your file

As files grow and require more disk space, assigned clusters are chained together

The chain can be broken or fragmented

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

Examining FAT Disks (5 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Examining FAT Disks (6 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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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

Examining FAT Disks (7 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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In Microsoft OSs, when a file is deleted

Directory entry is marked as a deleted file

With the HEX E5 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

Deleting FAT Files

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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NT File System (NTFS)

Introduced with Windows NT

Primary file system for Windows 10

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

It records a transaction before the system carries it out

Examining NTFS Disks (1 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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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 (2 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Examining NTFS Disks (3 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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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 System Files (1 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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NTFS File System (2 of 3)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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NTFS File System (3 of 3)

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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

MFT and File Attributes (1 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Files larger than 512 bytes are stored outside the MFT

MFT record provides cluster addresses where the file is stored on the drive’s partition

Referred to as data runs

Each MFT record starts with a header identifying it as a resident or nonresident attribute

MFT and File Attributes (2 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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MFT and File Attributes (3 of 7)

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MFT and File Attributes (4 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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MFT and File Attributes (5 of 7)

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MFT and File Attributes (6 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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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

When data is first written to nonresident files, an LCN address is assigned to the file

This LCN becomes the file’s virtual cluster number (VCN)

MFT and File Attributes (7 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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For the header of all MFT records, the record fields of interest are as follows:

At offset 0x00 – the MFT record identifier FILE

At offset 0x1C to 0x1F – size of the MFT record

At offset 0x14 – length of the header (indicates where the next attribute starts)

At offset 0x32 and 0x33 – the update sequence array, which stores the last 2 bytes of the first sector of the MFT record

MFT Structures for File Data (1 of 7)

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MFT Structures for File Data (2 of 7)

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MFT Structures for File Data (3 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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MFT Structures for File Data (4 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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MFT Structures for File Data (5 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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MFT Structures for File Data (6 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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MFT Structures for File Data (7 of 7)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Alternate data streams

Ways data can be appended to existing files

Can obscure valuable evidentiary data, intentionally or by coincidence

In NTFS, an alternate data stream becomes an additional file attribute

Allows the file to be associated with different applications

You can only tell whether a file has a data stream attached by examining that file’s MFT entry

NTFS Alternate Data Streams (1 of 2)

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NTFS Alternate Data Streams (2 of 2)

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NTFS provides compression similar to FAT DriveSpace 3 (a Windows 98 compression utility)

With NTFS, files, folders, or entire volumes can be compressed

Most computer forensics tools can uncompress and analyze compressed Windows data

NTFS Compressed Files

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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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 and later

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

NTFS Encrypting File System (EFS)

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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Recovery Key Agent implements the recovery certificate

Which is in the Windows administrator account

Windows administrators can recover a key in two ways: through Windows or from a command prompt

Commands:

cipher

copy

EFS Recovery Key Agent

© 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.

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