Digital Forensics

Dr. Bhavani Thuraisingham

The University of Texas at Dallas

Lecture #7

Processing Crime and Incident Scene

September 17, 2008

Outline

Review Processing crime and Incident Scenes Review Questions Reference: Chapters 2 and 5 of textbook End of Part I of Course

Review

Lecture 1: Overview of Digital Forensics (Chapter 1 of textbook)

Lecture 2: Information Security Review Lecture 3: Data Recovery, Verification, Lab Tour (Chapter 3 of

textbook – constructing a forensics lab) Lecture 4: Data Acquisition: Chapter 4 of textbook Lecture 5: Malicious Code Detection (e.g., Computer is the

Victim of the Crime; applying data mining techniques) Lecture 6: Digital Forensics Analysis – Part 1

Processing Crime and Incident Scenes

Topics in Chapter 2

- Securing evidence

- Gathering evidence

- Analyzing evidence Topics in Chapter 5

- Understanding the rules of evidence

- Collecting evidence in private-sector incident scenes

- Processing law enforcement crime scenes

- Steps to Processing Crime and Incident Scenes

- Case study Other topics

- Forensics technologies

Securing Evidence

To secure and catalog evidence large evidence bags, tapes, tags, labels, etc. may be used

Tamper Resistant Evidence Security Bags

- Example: EVIDENT

- “These heavy-duty polyethylene evidence bags require no prepackaging of evidence prior to use. The instantaneous adhesive closure strip is permanent and impossible to open without destroying the seal. A border pattern around the edge of the bag reveals any attempt at cutting or tampering with evidence.”

See also the work of SWDGE (Scientific Working Group on Digital Evidence) and IOCE (International Organization on Computer Evidence)

Gathering Evidence

Bit Stream Copy

- Bit by bit copy of the original drive or storage medium

- Bit stream image is the file containing the bit stream copy of all data on a disk

Using ProDiscover to acquire a thumb drive

- On a thumb drive locate the write protect switch and place drive in write protect model

- Start ProDiscover

- Click Action, Capture Image from menu

- Click Save

- Write name of technician

- Use hash algorithms for security

- Click OK

- See also discussion in lecture 4

Analyzing Evidence

Start ProDiscover Create new file Click on image file to be analyzed Search for keywords, patterns and enter patterns to be

searched Click report and export file Details in Chapter 2

Understanding the Rules of Evidence

Federal rules of evidence; each state also may have its own rules of evidence

- www.usdoj.gov Computer records are in general hearsay evidence unless

they qualify as business records

- Hearsay evidence is second hand or indirect evidence

- Business records are records of regularly conducted business activity such as memos, reports, etc.

Computer records consist of computer generated records and computer stored records

Computer generated records include log files while computer stored records are electronic data

Al computer records must be authentic

Private sector incident scenes

Corporate investigations

- Employee termination cases, Attorney-Client privilege investigations, Media leak investigations, Industrial espionage investigations

Private sector incident scenes

- Private section includes private corporations and government agencies not involved with law enforcement

- They must comply with state public disclosure and federal Freedom of Information act and make certain documents available as public records

- Law enforcement is called if needed (if the investigation becomes a criminal investigation)

Law Enforcement crime Scenes

A law enforcement officer may seize criminal evidence only with probable cause

- A specific crime was committed

- Evidence of the crime exists

- Place to searched includes the evidence The forensics team should know about the terminology used

in warrants To prepare for a search and carry out an investigation the

following steps have to be carried out

- Identifying the nature of the case, the type of computing system, determine whether computer can be seized, identify the location, determine who is in charge, determine the tools

Steps to processing crime and incident scenes (Details in Chapter 5)

Seizing a computer incident or crime scene Sizing the digital evidence at crime scene Storing the digital evidence Obtaining a digital hash Conducting analysis and reporting

Case Study (Chapter 5)

Company A (Mr. Jones) gets an order for widgets from Company B. When the order is ready, B says it did not place the order. A then retrieves the email sent by B. B states it did not send the email. What should A do?

Steps to carry out

- Close Mr. Jones Outlook

- User windows explorer to locate Outlook PST that has Mr.,. Jones business email

- Determine the size of PST and connect appropriate media device (e.g. USB)

- Copy PST into external USB

- Fill out evidence form – date/time etc.

- Leave company A and return to the investigation desk and carry out the investigation (see previous lectures)

Other Topics: Forensics technologies

Forensics Technology

- Military, Law Enforcement, Business Forensics Forensics Techniques

- Finding Hidden Data, Spyware, Encryption, Data Protection, Tracing, Data Mining

Security Technologies

- Wireless, Firewalls, Biometrics

Military Forensics

CFX-2000: Computer Forencis Experiment 2000

- Information Directorate (AFRL) partnership with NIJ/NLECTC

- Hypothesis: possible to determine the motives, intent, targets, sophistication, identity and location of cyber terrorists by deploying an integrated forensics analysis framework

- Tools included commercial products and research prototypes

- http://www.afrlhorizons.com/Briefs/June01/IF0016.html

- http://rand.org/pubs/monograph_reports/MR1349/MR1349.appb.pdf

Law Enforcement Forensics

Commonly examined systems: Windows NT, Windows 2000, XP and 2003

Preserving evidence

- Mirror image backups: Safe Back technology from New Technologies Inc.

Tools to handle

- Trojan Horse programs / File slacks

- Data Hiding Techniques AnaDisk analyzes diskettes COPYQM duplicates diskettes

- E-Commerce investigation: Net Threat Analyzer

- Text search: TextSearch Plus tool

- Fuzzy logic/data mining tools to identify unknown text Intelligent Forensics Filter

Business Forensics

Remote monitoring of target computers

- Data Interception by Remote Transmission (DIRT) from Codex Data Systems

Creating trackable electronic documents Theft recovery software for laptops and PCs

- PC Phonehome tool

- RFID technology

Forensics Techniques

Techniques for finding, preserving and preparing evidence Finding evidence is a complex process as the forensic expert

has to determine where the evidence resides

- Evidence may be in files, evidence may be in disks, evidence may be on paper. Need to track all types of evidence

Preserving evidence includes ensuring that the evidence is not tampered with

- Involves pre-incident planning and training in incident discovery procedures’ If the machine is turned on, leave it on; do not run programs on that particular computer

Preparing evidence will include data recovery, documentation, etc.

Finding Hidden Data

When files are deleted, usually they can be recovered The files are marked as deleted, but they are still residing in

the disk until they are overwritten Files may also be hidden in different parts of the disk The challenge is to piece the different part of the file together

to recover the original file There is research on using statistical methods for file

recovery http://www.cramsession.com/articles/files/finding-hidden-data

---how-9172003-1401.asp http://www.devtarget.org/downloads/ca616-seufert-

wolfgarten-assignment2.pdf

Spyware/Adware

Spyware is computer software that is installed surreptitiously on a personal computer to intercept or take partial control over the user's interaction with the computer, without the user's informed consent.

- http://en.wikipedia.org/wiki/Spyware Spyware is mostly advertising supported software (adware) Shareware authors place ads from media company and get a

piece if the revenue PC surveillance tools that allow a user to nominate computer

activity

- Keystroke capture, snapshots, email logging, chats etc. Privacy concerns with spyware

Encryption

Popular Encryption techniques

- Public key/ Private Key Owner of the data encrypts with the public key of the

receiver; Receiver decrypts with his private key In some cases owner may encrypt with his private key for

multiple receiver. Receiver will decrypt with the owner’s public key

Merkle Hash is a popular method to hash documents; one way hash function

Challenge is to generate unique keys Issues: Trusted authority to generate keys and credentials

Internet/Web Tracing

Where has the email come from

- Check IP address

- Sender may use fake address by changing fields; sending server may not check this and so the mail is sent

Tracing web activity Who has logged into the system say from a public web site

and modified accounts and grades? Web/email tracking tools

- http://www.cryer.co.uk/resources/websitetracking.htm

- http://www.visualware.com/resources/tutorials/email.html

Wireless Technology Forensics Forensic Examination of a RIM (BlackBerry) Wireless Device

http://www.rh-law.com/ediscovery/Blackberry.pdf

- “There are two types of RIM devices within each model class. The Exchange Edition is meant

for use in a corporate environment while the Internet Edition works with standard POP email

accounts. The Exchange Edition employs Triple-DES encryption to send and receive but the

Internet Edition communicates in clear text. Neither employs an encrypted files system”

Relevance of RIM forensics

- “The RIM device shares the same evidentiary value as any other Personal Digital Assistant

(PDA). As the investigator may suspect of most file systems, a delete is by no means a total

removal of data on the device. However, the RIM’s always-on, wireless push technology adds

a unique dimension to forensic examination. Changing and updating data no longer requires a

desktop synchronization. In fact, a RIM device does not need a cradle or desktop connection

to be useful. The more time a PDA spends with its owner, the greater the chance is that it will

more accurately reflect and tell a story about that person. Thus, the RIM’s currently

unsurpassed portability is the examiner’s greatest ally”

Wireless Technology Forensics - 2 The Hardware

- The RIM device is designed around an Intel 32-bit i386 processor, a low power

embedded version of the same processor that used to power a desktop PC. Each unit

has 512 KB of SRAM and 4 or 5 MB of Flash RAM, depending on the model. The RIM’s

SRAM is analogous to the RAM on a desktop and the Flash memory is the “disk space”

used to store the Operating System (OS), applications, and the file system. The RIM’s

OS is a single executable named PAGER.EXE and the applications are DLL’s.

Toolbox

- BlackBerry Desktop Software available free at www.blackberry.com; BlackBerry C++

Software Development Kit v2.1 available free at www.blackberry.com; • Hex editor; • Text

editor; • AA batteries; • Spare BlackBerry Cradles

- The examination PC should meet the minimum requirements for the BlackBerry Software

Development Kit (SDK) and have two available external 9-pin RS232 serial ports. Disk

space required for evidence gathering is minimal: space equal to the amount of Flash

RAM in the RIM units being investigated.

Firewall Forensics http://www.linuxsecurity.com/resource_files/firewalls/firewall-

seen.html Analyzing firewall logs, especially what port numbers etc.

mean?. May use this information to help figure out what hackers are up to.

- What does destination port number ZZZZ mean?

- What does this ICMP info mean?

- What do these IP addresses indicate?

- Stuff doesn't work

- What are some typical signatures of well-known programs?

- What do these other logs mean?

- How do I configure filters?

- Packet Zen

- What's the deal with NetBIOS (UDP port 137)?

Biometrics Forensics: Richard Vorder Bruegge

http://www.biometrics.org/bc2004/Bios/vorderbruegge_bio_OK.pdf

http://www.biometrics.org/bc2004/Presentations/Conference/2%20Tuesday%20September%2021/Tue_Ballroom%20B/1%20DOJ%20Session/Vorderbruegge_Presentation.pdf

It often happens that people confuse biometrics and forensics. After all, television and movies make it look like automated biometrics databases can be used to identify and convict people all the time. Isn't that what forensics is all about? Unfortunately, this can have an adverse affect on the development of forensic tools which utilize biometric features, because those in position to make funding decisions may not understand the distinction between the two. This presentation will attempt to provide the audience with a better understanding of the relationship between biometrics and forensics from the standpoint of a forensic scientist.

Biometrics Forensics: Richard Vorder Bruegge

Advances in the field of biometrics offers great potential for the field of forensics. Biometric databases offer the promise of enabling law enforcement and the intelligence community to rapidly identify questioned individuals if they are present in the queried database. However, obtaining a "hit" in a biometric database is a far cry from an identification in the world of forensic science. The standard of proof to which forensic scientists in the United States are held is "beyond a reasonable doubt". That "reasonable doubt" criteria, coupled with standards for scientific and technical evidence elucidated in the "Daubert" and "Kumho Tire" cases, require that conclusions offered by forensic scientists be supported at beyond that offered by current biometric systems, particularly in the field of facial recognition.

http://forensic-evidence.com/site/ID/ID_prime_qd.html Reviewing Court Approves of Fingerprint Admissibility

Review Questions (Lectures 1, 3-7)

Describe what is meant by digital forensics Describe the steps for a forensic investigation Describe how Data is Acquired in a Forensics Investigation Describe the process of constructing a forensic lab Describe data recovery in a forensic investigation Describe verification aspects of a forensic investigation Describe for malicious code may be detected in a machine Describe techniques for digital forensics analysis Describe the steps involved in processing a crime scene Describe the rules of evidence Describe forensics technologies