VISHVESHWARAIAH TECHNOLOGICAL UNIVERSITY S.D.M COLLEGE …sdmcse2006.pbworks.com/f/2SD06CS110.pdf · A seminar report on “COMPUTER FORENSICS ... CONTENT Introduction ... The File

VISHVESHWARAIAH TECHNOLOGICAL UNIVERSITY

S.D.M COLLEGE OF ENGINEERING AND TECHNOLOGY

A seminar report on

“COMPUTER FORENSICS”

Submitted by

„SUJAY P.‟

„2SD06CS110‟

8th

semester

DEPARTMENT OF COMPUTER SCIENCE ENGINEERING

Computer Forensics

COMPUTER SCIENCE & ENGINEERING Page 2

VISHVESHWARAIAH TECHNOLOGICAL UNIVERSITY

S.D.M COLLEGE OF ENGINEERING AND TECHNOLOGY

DEPARTMENT OF COMPUTER SCIENCE ENGINEERING

CERTIFICATE

Certified that the seminar work entitled “COMPUTER FORENSICS”

Is a bonafide work presented by „SUJAY P.‟

baring USN NO „2SD06CS110‟

in a partial fulfillment for the award of degree of Bachelor of Engineering in computer science

of the Vishveshwaraiah Technological University, Belgaum during the year 2009-10. The seminar

report has been approved as it satisfies the academic requirements with respect to seminar work

presented for the Bachelor of Engineering Degree

.Staff in charge Prof S.L DESHPANDE H.O.D

Computer Forensics


CONTENT

Introduction

History of Computer Forensics

Steps of Computer Forensics

Reasons for Evidence

Users Computer Forensics

Handling Evidence

Handling Information

Evidence Processing Guidelines

Methods of Hiding Data

Methods of Detecting/Recovering Data

Network forensics

Advantages of Computer Forensics

Disadvantages of Computer Forensics

Conclusion

Computer Forensics


Introduction

Computer forensics is simply the application of disciplined investigative techniques

in the automated environment and the search, discovery, and analysis of potential evidence. It

is the method used to investigate and analyze data maintained on or retrieved from electronic

data storage media for the purposes of presentation in a court of law, civil or administrative

proceeding. Evidence may be sought in a wide range of computer crime or misuse cases.

Computer forensics is rapidly becoming a science recognized on a par with other forensic

sciences by the legal and law enforcement communities. As this trend continues, it will

become even more important to handle and examine computer evidence properly. Not every

department or organization has the resources to have trained computer forensic specialists on

staff.

Computer evidence has become a „fact of life' for essentially all law enforcement

agencies and many are just beginning to explore their options in dealing with this new venue.

Almost overnight, personal computers have changed the way the world does business. They

have also changed the world‟s view of evidence because computers are used more and more

as tools in the commission of „traditional' crimes. Evidence relative to embezzlement, theft,

extortion and even murder has been discovered on personal computers. This new technology

twist in crime patterns has brought computer evidence to the forefront in law enforcement

circles.

Forensic science has been defined as “any science used for the purposes of the law...

[Providing] impartial scientific evidence for use in the courts of law, and in a criminal

investigation and trial”.

According to Marcus Ranum, “Network forensics is the capture, recording, and

analysis of network events in order to discover the source of security attacks or other

problem incidents”.

Computer Forensics


We expand on these definitions to define computer forensics as:

“Computer forensics involves the preservation, identification, extraction, documentation,

and interpretation of computer media for evidentiary and/or root cause analysis.”

These activities are undertaken in the course of a computer forensic investigation of a

perceived or actual attack on computer resources. Evidence might be required for a wide

range of computer crimes and misuses.

Multiple methods of

Discovering data on computer system.

Recovering deleted, encrypted, or damaged file information.

Monitoring live activity.

Detecting violations of corporate policy.

Information collected assists in arrests, prosecution, termination of employment, and

preventing future illegal activity.

What Constitutes Digital Evidence?

Any information being subject to human intervention or not, that can be extracted

from a computer.

Must be in human-readable format or capable of being interpreted by a person with

expertise in the subject.

Computer Forensics


Computer Forensics Examples

Recovering thousands of deleted emails.

Performing investigation post employment termination.

Recovering evidence post formatting hard drive.

Performing investigation after multiple users had taken over the system.

History of Computer Forensics

Michael Anderson

“Father of computer forensics”.

Special agent with IRS.

Meeting in 1988 (Portland, Oregon)

Creation of IACIS, the International Association of Computer Investigative

Specialists.

The first Seized Computer Evidence Recovery Specialists (SCERS) classes

held.

Computer Forensics


Steps of Computer Forensics

Computer Forensics is a four (4) step process

Acquisition

Physically or remotely obtaining possession of the computer, all network mappings

from the system, and external physical storage devices.

Identification

This step involves identifying what data could be recovered and electronically

retrieving it by running various Computer Forensic tools and software suites.

Evaluation

Evaluating the information/data recovered to determine if and how it could be used

again the suspect for employment termination or prosecution in court.

Presentation

This step involves the presentation of evidence discovered in a manner which is

understood by lawyers, non-technically staff/management, and suitable as evidence as

determined by United States and internal laws.

Computer Forensics


Computer forensics process

Computer Forensics


Reasons for Evidence

Wide range of computer crimes and misuses

Non-Business Environment: evidence collected by Federal, State and local authorities

for crimes relating to:

Theft of trade secrets

Frauda

Extortion

SPAM investigations

Virus/Trojan distribution

Homicide investigations

Intellectual property breaches

Unauthorized use of personal information

Forgery

Computer related crime and violations include a range of activities including:

Business Environment:

Theft of or destruction of intellectual property

Unauthorized activity

Tracking internet browsing habits

Reconstructing Events

Inferring intentions

Selling company bandwidth

Software Piracy

Computer Forensics


Users Computer Forensics

Criminal Prosecutors

◦ Rely on evidence obtained from a computer to prosecute suspects and use as

evidence.

Civil Litigations

◦ Personal and business data discovered on a computer can be used in fraud,

divorce, harassment, or discrimination cases.

Insurance Companies

◦ Evidence discovered on computer can be used to mollify costs.

Private Corporations

◦ Obtained evidence from employee computers can be used as evidence in

harassment, fraud, and embezzlement cases.

Law Enforcement Officials

◦ Rely on computer forensics to backup search warrants and post-seizure

handling.

Individual/Private Citizens

Obtain the services of professional computer forensic specialists to support

claims of harassment, abuse, or wrongful termination from employment.

Computer Forensics


Handling Evidence

Admissibility of Evidence

◦ Legal rules which determine whether potential evidence can be considered by

a court.

◦ Must be obtained in a manner which ensures the authenticity and validity and

that no tampering had taken place.

No possible evidence is damaged, destroyed, or otherwise compromised by the

procedures used to search the computer.

Preventing viruses from being introduced to a computer during the analysis process.

Extracted / relevant evidence is properly handled and protected from later mechanical

or electromagnetic damage.

Establishing and maintaining a continuing chain of custody.

Limiting the amount of time business operations are affected.

Not divulging and respecting any ethically [and legally] client-attorney information

that is inadvertently acquired during a forensic exploration.

Computer Forensics


Handling Information

Information and data being sought after and collected in the investigation must be

properly handled.

Volatile Information

◦ Network Information

Communication between system and the network.

◦ Active Processes

Programs and daemons currently active on the system.

◦ Logged-on Users

Users/employees currently using system.

◦ Open Files

Libraries in use; hidden files; Trojans (root kit) loaded in system.

Non-Volatile Information

◦ This includes information, configuration settings, system files and registry

settings that are available after reboot.

◦ Accessed through drive mappings from system.

◦ This information should investigate and reviewed from a backup copy.

Computer Forensics


Evidence Processing Guidelines

Following are the 16 recommended steps in processing evidence

Step 1: Shut down the computer

◦ Considerations must be given to volatile information.

◦ Prevents remote access to machine and destruction of evidence (manual or ant-

forensic software).

Step2: Document the Hardware Configuration of the System.

◦ Note everything about the computer configuration prior to re-locating.

Step 3: Transport the Computer System to a Secure Location

◦ Do not leave the computer unattended unless it is locked in a secure location.

Step 4: Make Bit Stream Backups of Hard Disks and Floppy Disks.

Step 5: Mathematically Authenticate Data on All Storage Devices

◦ Must be able to prove that you did not alter any of the evidence after the

computer came into your possession.

Step 6: Document the System Date and Time.

Step 7: Make a List of Key Search Words.

Step 8: Evaluate the Windows Swap File.

Step 9: Evaluate File Slack

◦ File slack is a data storage area of which most computer users are unaware; a

source of significant security leakage.

Computer Forensics


Step 10: Evaluate Unallocated Space (Erased Files).

Step 11: Search Files, File Slack and Unallocated Space for Key Words.

Step 12: Document File Names, Dates and Times.

Step 13: Identify File, Program and Storage Anomalies.

Step 14: Evaluate Program Functionality.

Step 15: Document Your Findings.

Step 16: Retain Copies of Software Used.

Computer Forensics


Methods of Hiding Data

To human eyes, data usually contains known forms, like images, e-mail, sounds, and

text. Most Internet data naturally includes gratuitous headers, too. These are media

exploited using new controversial logical encodings: steganography and marking.

Steganography: The art of storing information in such a way that the existence of the

information is hidden.

Watermarking: Hiding data within data

Information can be hidden in almost any file format.

File formats with more room for compression are best

Image files (JPEG, GIF)

Sound files (MP3, WAV)

Video files (MPG, AVI)

The hidden information may be encrypted, but not necessarily.

Numerous software applications will do this for you: Many are freely

available online.

Hard Drive/File System manipulation

Slack Space is the space between the logical end and the physical end of file

and is called the file slack. The logical end of a file comes before the physical

end of the cluster in which it is stored. The remaining bytes in the cluster are

remnants of previous files or directories stored in that cluster.

Slack space can be accessed and written to directly using a hex

editor.

This does not add any “used space” information to the drive.

Hidden drive space is non-partitioned space in-between partitions

Computer Forensics


The File Allocation Table (FAT) is modified to remove any reference

to the non-partitioned space.

The address of the sectors must be known in order to read/write

information to them.

Bad sectors occur when the OS attempts to read info from a sector

unsuccessfully. After a (specified) number of unsuccessful tries, it copies (if

possible) the information to another sector and marks (flags) the sector as bad

so it is not read from/written to again.

users can control the flagging of bad sectors.

Flagged sectors can be read to /written from with direct reads and

writes using a hex editor.

Extra Tracks: most hard disks have more than the rated number of tracks to

make up for flaws in manufacturing (to keep from being thrown away because

failure to meet minimum number).

Usually not required or used, but with direct (hex editor) reads and

writes, they can be used to hide/read data.

Change file names and extensions – i.e. rename a .doc file to a .dll file.

Computer Forensics


Methods of Detecting/Recovering Data

• Steganalysis - the art of detecting and decoding hidden data.

– Hiding information within electronic media requires alterations of the media

properties that may introduce some form of degradation or unusual

characteristics.

– The pattern of degradation or the unusual characteristic of a specific type of

steganography method is called a signature.

– Steganalysis software can be trained to look for a signature.

Steganalysis Methods - Detection

– Human Observation

• Opening a text document in a common word processor may show

appended spaces and “invisible” characters.

• Images and sound/video clips can be viewed or listened to and

distortions may be found.

• Generally, this only occurs if the amount of data hidden inside the

media is too large to be successfully hidden within the media (15%

rule).

– Software analysis

• Even small amounts of processing can filter out echoes and shadow

noise within an audio file to search for hidden information.

• If the original media file is available, hash values can easily detect

modifications.

– Disk analysis utilities can search the hard drive for hidden

tracks/sectors/data.

Computer Forensics


– RAM slack is the space from the end of the file to the end of the containing

sector. Before a sector is written to disk, it is stored in a buffer somewhere in

RAM. If the buffer is only partially filled with information before being

committed to disk, remnants from the end of the buffer will be written to disk.

In this way, information that was never "saved" can be found in RAM slack

on disk.

– Firewall/Routing filters can be applied to search for hidden or invalid data in

IP datagram headers.

– Statistical Analysis

• Most steganographic algorithms that work on images assume that the

Least Significant Bit (LSB) is random

• If a filter is applied to an image, the LSB bits will produce a

recognizable image, so the assumption is wrong

• After inserting hidden information into an image, the LSB is no longer

non-random (especially with encrypted data). If you apply the same

filter, it will no longer produce a recognizable image

• Statistical analysis of the LSB will tell you if the LSB bits are random

or not

• Can be applied to audio files as well (using LSB)

– Frequency scanning

• Software can search for high, inaudible frequencies.

Steganalysis methods – Recovery

– Recovery of watermarked data is extremely hard.

• Currently, there are very few methods to recover hidden, encrypted

data.

Computer Forensics


– Data hidden on disk is much easier to find. Once found, if unencrypted, it is

already recovered

– Deleted data can be reconstructed (even on hard drives that have been

magnetically wiped)

– Check swap files for passwords and encryption keys which are stored in the

clear (unencrypted)

– Software Tools

• Scan for and reconstruct deleted data

• Break encryption

Example:

GetFree - Forensic Data Capture Tool When files are 'deleted' in DOS, Windows, Windows

95 and Windows 98, the data associated with the file is not actually eliminated. It is simply

reassigned to unallocated storage space where it may eventually be overwritten by the

creation of new files over time. Such data can provide the computer forensics investigator

with valuable leads and evidence.

GetSlack - Forensic Data Capture Utility this software is used to capture all of the file slack

contained on a logical hard disk drive or floppy diskette on a DOS, Windows, Windows 95

and/or Windows 98 computer system. The resulting output from GetSlack can be analyzed

with standard computer utilities or with special NTI tools, e.g., Filter_I and Net Threat

Analyzer software.

Forensic Graphics File Extractor - NTI's Forensic Graphics Image File Extractor is a

computer forensics software tool which was designed to automatically extract exact copies of

graphics file images from ambient data sources and from SafeBack bit stream image backup

files. The latter process has the potential of quickly identifying all graphics file images stored

Computer Forensics


on a computers hard disk drive. The resulting output image files can be quickly evaluated

using a graphics file viewer.

DiskScrub - Hard Drive Data Elimination Software It is becoming standard practice in

corporations, government agencies, law firms and accounting firms to reassign computers

and to donate older computers to charity. Millions of personal computers have been put to

use since 1981 when the IBM Personal Computer came into existence. Many of the older

personal computers have been reassigned or donated to charity and many more will fall into

this category in the future. However, data security is often ignored when computers change

hands. You must be aware that personal computers were never designed with security in

mind. Potentially anything that transpired on a used computer still exists. Multiply that by the

number of computers your organization will reassign or surplus this year, and you get the

point. Computers should be reassigned and donated to charity but the contents of the hard

disk drives should not be ignored. With computer technology changing almost daily,

corporations and government agencies have to stay current while still making the best uses of

aging computer resources. Advancements in hard disk drive storage capacities, operating

systems and software applications cause corporations to buy or lease new computers every

year.

But what is done with the old computers? What is done about the sensitive data still

Existing, essentially "stored" on these computers when they are sold, transferred or donated?

That is a serious problem, and NTI's Disk Scrub software was specifically designed to deal

with these risks, for corporations, government agencies, hospitals, financial institutions, law

firms and accounting firms.

Computer Forensics


Computer Forensics


Network forensics

As technology has advanced, computers have become incredibly powerful.

Unfortunately, as computers get more sophisticated, so do the crimes committed with them.

Distributed Denial of Service Attacks, ILOVEYOU and other viruses, Domain Name

Hijacking, Trojan Horses, and Websites shut down are just a few of the hundreds of

documented attack types generated by computers against other computers usually using an

electronic network. The need for security measures to prevent malicious attacks is well

recognized and is a fertile research area as well as a promising practioner's marketplace.

Though there is an immense effort ongoing to secure computer systems and prevent attacks,

it is clear that computer and network attacks will continue to be successful. When attacks are

successful, forensics techniques are needed to catch and punish the perpetrators, as well as to

allow recovery of property and/or revenue lost in the attack. Computer and Network

Forensics (CNF) techniques are used to discover evidence in a variety of crimes ranging from

theft of trade secrets, to protection of intellectual property, to general misuse of computers.

The ultimate goal of computer and network forensics is to provide sufficient evidence to

allow the criminal perpetrator to be successfully prosecuted. As such, CNF efforts are mainly

centered in law enforcement agencies. Any enterprise that depends on, or utilizes, computers

and networks should have a balanced concern for security and forensic capabilities.

Unfortunately, there is little academic or industrial research literature available on CNF.

Forensic techniques are developed by the try and fix method, and few organizations have

plans for conducting forensics in response to successful attacks. We propose several

categories of policies that will help enterprises deter computer crime and will position them

to respond effectively to successful attacks by improving their ability to conduct computer

and network forensics. These policies correlate to taxonomy of approaches common to

computer attacks. We present policies in the following categories: Retaining Information,

Planning the Response, Training, Accelerating the Investigation, Preventing Anonymous

Activities and Protecting the Evidence.

The evidence found during a forensic investigation may depend on the type of crime

committed. For example, in a criminal case, incriminating evidence may be found such as

documents related to homicides, financial fraud, drug or embezzlement record keeping, or

Computer Forensics


child pornography. In a civil case, evidence of personal and business records related to fraud,

divorce, discrimination, or harassment could be found.

CNF experts are not only hired by lawyers. CNF techniques are sometimes needed by

insurance companies to discover evidence to decrease the amount paid in an insurance claim.

Individuals may also hire CNF experts to support a claim of wrongful termination, sexual

harassment, or discrimination. Gathering evidence is at the heart of CNF. In computer-related

crimes, evidence is accumulated from information collected by different components of the

system. The information does not become evidence until a crime is committed and this data

is used to find clues. For this reason, we call the data collected by the system potential

evidence. There are many sources of potential evidence in computers and network

components. Files are an obvious source of potential evidence. Application output word

processors, spread sheets, etc. are almost always valuable potential evidence, as are hidden

application files that may contain history information, caches, backups, or activity logs.

Occasionally, sophisticated criminals may encrypt incriminating files or attempt to hide them

with system-oriented or otherwise unlikely looking names. There are numerous sources of

potential evidence, which we discuss more exhaustingly in the section dedicated to

establishing recommended policies. Because gathering potential evidence may not be as easy

as finding application files on a computer, it requires someone with special skills. CNF

experts are specially trained with the skills necessary to successfully carry out a forensic

investigation. A forensics expert must have the investigative skills of a detective, the legal

skills of a lawyer, and the computing skills of the criminal. Even with these skills, CNF is not

an exact science, so there is no guarantee that an expert will find sufficient evidence.

However, experienced forensics specialists can find more potential evidence than even the

best hackers will expect.

Computer Forensics


Advantages of Computer Forensics

It has an ability to search through a massive amount of data

Quickly

Easily

Thoroughly

In any language

Disadvantages of Computer Forensics

Digital evidence accepted into court

Must prove that there is no tampering.

All evidence must be fully accounted for.

Computer forensic specialists must have complete knowledge of legal

requirements, evidence handling and storage and documentation procedures

Costs.

Producing electronic records & preserving them is extremely costly.

Presents the potential for exposing privileged documents.

Legal practitioners must have extensive computer knowledge.

Computer Forensics


Conclusion

Practical investigations tend to rely on multiple streams of evidence which

corroborate each other - each stream may have its weaknesses, but taken together may point

to a single conclusion. Disk forensics may remain for some time the single most important

form of digital evidence .Increasing number of computer crime means increasing demand for

computer forensics services. In doing computer forensics investigation, choosing the right

disk imaging tool is very important. There is no standard conformity of computer forensic

imaging methodology or tool. This paper only provides guidance and suggestions regarding

imaging tool. It should not be constructed as mandatory requirement.

Today, everyone is exposed to potential attacks and has a responsibility to its network

neighbors to minimize their own vulnerabilities in an effort to provide a more secure and

stable network. As the enormity of the problem unfolds, we will better comprehend how vital

it is to work towards dramatic changes in research, prevention, detection and reporting, and

computer crime investigation. Security can no longer be thought of as an impediment to

accomplishing the mission, but rather a basic requirement that is properly resourced.

Our focus has been to implement the newest and most advanced technology, but little

has prepared us for the gaping security holes we‟ve neglected to mend along the way. From

the ranks of management to every employee that works behind each terminal, the policies

that protect and mitigate risks must be current, understood, and aggressively enforced.

Reporting must be standard operating procedure so that everyone can realize the total impact

and define what is required for a secure cyber environment. The responsibility belongs to

everyone and it is with that effort we will be able to harness the security of this new

technological age. An enormous challenge lies before us and we must attack it with the same

enthusiasm and determination that brought us to this new frontier.

Computer Forensics


References

All State Investigations, Inc. January 2005

http://www.alls

tateinvestigation.com/ComputerForensicServices.htm

Computer Forensics, Inc. http://www.forensics.com/

Computer Forensic Services, LLC. January 2005.

http://www.computer-forensic.com/index.html

International Association of Computer Investigative

Specialists. January 2005. http://www.cops.org/

Middlesex County Computer Technology. January

2005.

http://www.respond.com/countyguides/1800000002/NJ/

023

Virtue, Emily. “Computer Forensics: Implications for

Litigation and Dispute Resolutions.” April 2003.

http://ncf.canberra.edu.au/publications/emilyvirtue1.p

df

http://www.allstateinvestigation.com/ComputerForensicServices.htm

http://www.allstateinvestigation.com/ComputerForensicServices.htm

http://www.forensics.com/

http://www.computer-forensic.com/index.html

http://www.cops.org/

http://www.respond.com/countyguides/1800000002/NJ/023

http://www.respond.com/countyguides/1800000002/NJ/023

http://ncf.canberra.edu.au/publications/emilyvirtue1.pdf

http://ncf.canberra.edu.au/publications/emilyvirtue1.pdf

Documents

VISHVESHWARAIAH TECHNOLOGICAL UNIVERSITY S.D.M COLLEGE …sdmcse2006.pbworks.com/f/2SD06CS110.pdf · A seminar report on “COMPUTER FORENSICS ... CONTENT Introduction ... The File