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guide to the digital forensic and investigation
- 1. Chapter 1 Understanding TheDigital Forensics Profession and Investigations Guide to Computer Forensics and Investigations Fifth Edition
- 2. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 2 Objectives • Describe the field of digital forensics • Explain how to prepare computer investigations and summarize the difference between public- sector and private-sector investigations • Explain the importance of maintaining professional conduct • Describe how to prepare a digital forensics investigation by taking a systematic approach
- 3. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 3 Objectives • Describe procedures for private-sector digital investigations • Explain requirements for data recovery workstations and software • Summarize how to conduct an investigation, including critiquing a case
- 4. © Cengage Learning2015 An Overview of Digital Forensics • Digital forensics – The application of computer science and investigative procedures for a legal purpose involving the analysis of digital evidence after proper search authority, chain of custody, validation with mathematics, use of validated tools, repeatability, reporting, and possible expert presentation. – In October 2012, an ISO standard for digital forensics was ratified - ISO 27037 Information technology - Security techniques Guide to Computer Forensics and Investigations Fifth Edition 4
- 5. © Cengage Learning2015 An Overview of Digital Forensics • The Federal Rules of Evidence (FRE) was created to ensure consistency in federal proceedings – Signed into law in 1973 – Many states’ rules map to the FRE • FBI Computer Analysis and Response Team (CART) was formed in 1984 to handle cases involving digital evidence • By late 1990s, CART teamed up with Department of Defense Computer Forensics Laboratory (DCFL) Guide to Computer Forensics and Investigations Fifth Edition 5
- 6. © Cengage Learning2015 An Overview of Digital Forensics • The Fourth Amendment to the U.S. Constitution protects everyone’s right to be secure from search and seizure – Separate search warrants might not be necessary for digital evidence • Every U.S. jurisdiction has case law related to the admissibility of evidence recovered from computers and other digital devices Guide to Computer Forensics and Investigations Fifth Edition 6
- 7. © Cengage Learning2015 Digital Forensics and Other Related Disciplines • Investigating digital devices includes: – Collecting data securely – Examining suspect data to determine details such as origin and content – Presenting digital information to courts – Applying laws to digital device practices • Digital forensics is different from data recovery – Which involves retrieving information that was deleted by mistake or lost during a power surge or server crash Guide to Computer Forensics and Investigations Fifth Edition 7
- 8. © Cengage Learning2015 Digital Forensics and Other Related Disciplines • Forensics investigators often work as part of a team, known as the investigations triad Guide to Computer Forensics and Investigations Fifth Edition 8
- 9. © Cengage Learning2015 Digital Forensics and Other Related Disciplines • Vulnerability/threat assessment and risk management – Tests and verifies the integrity of stand-along workstations and network servers • Network intrusion detection and incident response – Detects intruder attacks by using automated tools and monitoring network firewall logs • Digital investigations – Manages investigations and conducts forensics analysis of systems suspected of containing evidence Guide to Computer Forensics and Investigations Fifth Edition 9
- 10. © Cengage Learning2015 A Brief History of Digital Forensics • By the early 1990s, the International Association of Computer Investigative Specialists (IACIS) introduced training on software for digital forensics • IRS created search-warrant programs • ASR Data created Expert Witness for Macintosh • ILook is currently maintained by the IRS Criminal Investigation Division • AccessData Forensic Toolkit (FTK) is a popular commercial product Guide to Computer Forensics and Investigations Fifth Edition 10
- 11. © Cengage Learning2015 Understanding Case Law • Existing laws can’t keep up with the rate of technological change • When statutes don’t exist, case law is used – Allows legal counsel to apply previous similar cases to current one in an effort to address ambiguity in laws • Examiners must be familiar with recent court rulings on search and seizure in the electronic environment Guide to Computer Forensics and Investigations Fifth Edition 11
- 12. © Cengage Learning2015 Developing Digital Forensics Resources • To supplement your knowledge: – Develop and maintain contact with computing, network, and investigative professionals – Join computer user groups in both the pubic and private sectors • Example: Computer Technology Investigators Network (CTIN) meets to discuss problems with digital forensics examiners encounter – Consult outside experts Guide to Computer Forensics and Investigations Fifth Edition 12
- 13. © Cengage Learning2015 Preparing for Digital Investigations • Digital investigations fall into two categories: – Public-sector investigations – Private-sector investigations Guide to Computer Forensics and Investigations Fifth Edition 13
- 14. © Cengage Learning2015 Preparing for Digital Investigations • Public-sector investigations involve government agencies responsible for criminal investigations and prosecution • Fourth Amendment to the U.S. Constitution – Restrict government search and seizure • The Department of Justice (DOJ) updates information on computer search and seizure regularly • Private-sector investigations focus more on policy violations Guide to Computer Forensics and Investigations Fifth Edition 14
- 15. © Cengage Learning2015 Understanding Law Enforcement Agency Investigations • When conducting public-sector investigations, you must understand laws on computer-related crimes including: – Standard legal processes – Guidelines on search and seizure – How to build a criminal case • The Computer Fraud and Abuse Act was passed in 1986 – Specific state laws were generally developed later Guide to Computer Forensics and Investigations Fifth Edition 15
- 16. © Cengage Learning2015 Following Legal Processes • A criminal investigation usually begins when someone finds evidence of or witnesses a crime – Witness or victim makes an allegation to the police • Police interview the complainant and writes a report about the crime • Report is processed and management decides to start an investigation or log the information in a police blotter – Blotter is a historical database of previous crimes Guide to Computer Forensics and Investigations Fifth Edition 16
- 17. © Cengage Learning2015 Following Legal Processes • Digital Evidence First Responder (DEFR) – Arrives on an incident scene, assesses the situation, and takes precautions to acquire and preserve evidence • Digital Evidence Specialist (DES) – Has the skill to analyze the data and determine when another specialist should be called in to assist • Affidavit - a sworn statement of support of facts about or evidence of a crime – Must include exhibits that support the allegation Guide to Computer Forensics and Investigations Fifth Edition 17
- 18. © Cengage Learning2015 Understanding Private-Sector Investigations • Private-sector investigations involve private companies and lawyers who address company policy violations and litigation disputes – Example: wrongful termination • Businesses strive to minimize or eliminate litigation • Private-sector crimes can involve: – E-mail harassment, falsification of data, gender and age discrimination, embezzlement, sabotage, and industrial espionage Guide to Computer Forensics and Investigations Fifth Edition 18
- 19. © Cengage Learning2015 Understanding Private-Sector Investigations • Businesses can reduce the risk of litigation by publishing and maintaining policies that employees find easy to read and follow • Most important policies define rules for using the company’s computers and networks – Known as an “Acceptable use policy” • Line of authority - states who has the legal right to initiate an investigation, who can take possession of evidence, and who can have access to evidence Guide to Computer Forensics and Investigations Fifth Edition 19
- 20. © Cengage Learning2015 Understanding Private-Sector Investigations • Business can avoid litigation by displaying a warning banner on computer screens – Informs end users that the organization reserves the right to inspect computer systems and network traffic at will Guide to Computer Forensics and Investigations Fifth Edition 20
- 21. © Cengage Learning2015 Understanding Private-Sector Investigations • Sample text that can be used in internal warning banners: – Use of this system and network is for official business only – Systems and networks are subject to monitoring at any time by the owner – Using this system implies consent to monitoring by the owner – Unauthorized or illegal users of this system or network will be subject to discipline or prosecution Guide to Computer Forensics and Investigations Fifth Edition 21
- 22. © Cengage Learning2015 Understanding Private-Sector Investigations • Businesses are advised to specify an authorized requester who has the power to initiate investigations • Examples of groups with authority – Corporate security investigations – Corporate ethics office – Corporate equal employment opportunity office – Internal auditing – The general counsel or legal department Guide to Computer Forensics and Investigations Fifth Edition 22
- 23. © Cengage Learning2015 Understanding Private-Sector Investigations • During private investigations, you search for evidence to support allegations of violations of a company’s rules or an attack on its assets • Three types of situations are common: – Abuse or misuse of computing assets – E-mail abuse – Internet abuse • A private-sector investigator’s job is to minimize risk to the company Guide to Computer Forensics and Investigations Fifth Edition 23
- 24. © Cengage Learning2015 Understanding Private-Sector Investigations • The distinction between personal and company computer property can be difficult with cell phones, smartphones, personal notebooks, and tablet computers • Bring your own device (BYOD) environment – Some companies state that if you connect a personal device to the business network, it falls under the same rules as company property Guide to Computer Forensics and Investigations Fifth Edition 24
- 25. © Cengage Learning2015 Maintaining Professional Conduct • Professional conduct - includes ethics, morals, and standards of behavior • An investigator must exhibit the highest level of professional behavior at all times – Maintain objectivity – Maintain credibility by maintaining confidentiality • Investigators should also attend training to stay current with the latest technical changes in computer hardware and software, networking, and forensic tools Guide to Computer Forensics and Investigations Fifth Edition 25
- 26. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 26 Preparing a Digital Forensics Investigation • The role of digital forensics professional is to gather evidence to prove that a suspect committed a crime or violated a company policy • Collect evidence that can be offered in court or at a corporate inquiry – Investigate the suspect’s computer – Preserve the evidence on a different computer • Chain of custody – Route the evidence takes from the time you find it until the case is closed or goes to court
- 27. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 27 An Overview of a Computer Crime • Computers can contain information that helps law enforcement determine: – Chain of events leading to a crime – Evidence that can lead to a conviction • Law enforcement officers should follow proper procedure when acquiring the evidence – Digital evidence can be easily altered by an overeager investigator • A potential challenge: information on hard disks might be password protected so forensics tools may be need to be used in your investigation
- 28. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 28 An Overview of a Company Policy Violation • Employees misusing resources can cost companies millions of dollars • Misuse includes: – Surfing the Internet – Sending personal e-mails – Using company computers for personal tasks
- 29. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 29 Taking a Systematic Approach • Steps for problem solving – Make an initial assessment about the type of case you are investigating – Determine a preliminary design or approach to the case – Create a detailed checklist – Determine the resources you need – Obtain and copy an evidence drive
- 30. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 30 Taking a Systematic Approach • Steps for problem solving (cont’d) – Identify the risks – Mitigate or minimize the risks – Test the design – Analyze and recover the digital evidence – Investigate the data you recover – Complete the case report – Critique the case
- 31. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 31 Assessing the Case • Systematically outline the case details – Situation – Nature of the case – Specifics of the case – Type of evidence – Known disk format – Location of evidence • Based on these details, you can determine the case requirements
- 32. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 32 Planning Your Investigation • A basic investigation plan should include the following activities: – Acquire the evidence – Complete an evidence form and establish a chain of custody – Transport the evidence to a computer forensics lab – Secure evidence in an approved secure container
- 33. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 33 Planning Your Investigation • A basic investigation plan (cont’d): – Prepare your forensics workstation – Retrieve the evidence from the secure container – Make a forensic copy of the evidence – Return the evidence to the secure container – Process the copied evidence with computer forensics tools
- 34. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 34 Planning Your Investigation • An evidence custody form helps you document what has been done with the original evidence and its forensics copies – Also called a chain-of-evidence form • Two types – Single-evidence form • Lists each piece of evidence on a separate page – Multi-evidence form
- 35. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 35 Planning Your Investigation
- 36. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 36 Planning Your Investigation
- 37. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 37 Securing Your Evidence • Use evidence bags to secure and catalog the evidence • Use computer safe products when collecting computer evidence – Antistatic bags – Antistatic pads • Use well padded containers • Use evidence tape to seal all openings – CD drive bays – Insertion slots for power supply electrical cords and USB cables
- 38. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 38 Securing Your Evidence • Write your initials on tape to prove that evidence has not been tampered with • Consider computer specific temperature and humidity ranges – Make sure you have a safe environment for transporting and storing it until a secure evidence container is available
- 39. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 39 Procedures for Private-Sector High- Tech Investigations • As an investigator, you need to develop formal procedures and informal checklists – To cover all issues important to high-tech investigations – Ensures that correct techniques are used in an investigation
- 40. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 40 Employee Termination Cases • The majority of investigative work for termination cases involves employee abuse of corporate assets • Incidents that create a hostile work environment are the predominant types of cases investigated – Viewing pornography in the workplace – Sending inappropriate e-mails • Organizations must have appropriate policies in place
- 41. © Cengage Learning2015 Internet Abuse Investigations • To conduct an investigation you need: – Organization’s Internet proxy server logs – Suspect computer’s IP address – Suspect computer’s disk drive – Your preferred computer forensics analysis tool Guide to Computer Forensics and Investigations Fifth Edition 41
- 42. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 42 Internet Abuse Investigations • Recommended steps – Use standard forensic analysis techniques and procedures – Use appropriate tools to extract all Web page URL information – Contact the network firewall administrator and request a proxy server log – Compare the data recovered from forensic analysis to the proxy server log – Continue analyzing the computer’s disk drive data
- 43. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 43 E-mail Abuse Investigations • To conduct an investigation you need: – An electronic copy of the offending e-mail that contains message header data – If available, e-mail server log records – For e-mail systems that store users’ messages on a central server, access to the server – Access to the computer so that you can perform a forensic analysis on it – Your preferred computer forensics analysis tool
- 44. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 44 E-mail Abuse Investigations • Recommended steps – Use the standard forensic analysis techniques – Obtain an electronic copy of the suspect’s and victim’s e-mail folder or data – For Web-based e-mail investigations, use tools such as FTK’s Internet Keyword Search option to extract all related e-mail address information – Examine header data of all messages of interest to the investigation
- 45. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 45 Attorney-Client Privilege Investigations • Under attorney-client privilege (ACP) rules for an attorney – You must keep all findings confidential • Many attorneys like to have printouts of the data you have recovered – You need to persuade and educate many attorneys on how digital evidence can be viewed electronically • You can also encounter problems if you find data in the form of binary files
- 46. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 46 Attorney-Client Privilege Investigations • Steps for conducting an ACP case – Request a memorandum from the attorney directing you to start the investigation – Request a list of keywords of interest to the investigation – Initiate the investigation and analysis – For disk drive examinations, make two bit-stream images using different tools for each image – Compare hash signatures on all files on the original and re-created disks
- 47. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 47 Attorney-Client Privilege Investigations • Steps for conducting an ACP case (cont’d) – Methodically examine every portion of the disk drive and extract all data – Run keyword searches on allocated and unallocated disk space – For Windows OSs, use specialty tools to analyze and extract data from the Registry – For binary data files such as CAD drawings, locate the correct software product – For unallocated data recovery, use a tool that removes or replaces nonprintable data
- 48. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 48 Attorney-Client Privilege Investigations • Steps for conducting an ACP case (cont’d) – Consolidate all recovered data from the evidence bit- stream image into folders and subfolders • Other guidelines – Minimize written communications with the attorney – Any documentation written to the attorney must contain a header stating that it’s “Privileged Legal Communication—Confidential Work Product” – Assist the attorney and paralegal in analyzing data
- 49. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 49 Industrial Espionage Investigations • All suspected industrial espionage cases should be treated as criminal investigations • Staff needed – Computing investigator who is responsible for disk forensic examinations – Technology specialist who is knowledgeable of the suspected compromised technical data – Network specialist who can perform log analysis and set up network sniffers – Threat assessment specialist (typically an attorney)
- 50. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 50 Industrial Espionage Investigations • Guidelines when initiating an investigation – Determine whether this investigation involves a possible industrial espionage incident – Consult with corporate attorneys and upper management – Determine what information is needed to substantiate the allegation – Generate a list of keywords for disk forensics and sniffer monitoring – List and collect resources for the investigation
- 51. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 51 Industrial Espionage Investigations • Guidelines (cont’d) – Determine goal and scope of the investigation – Initiate investigation after approval from management • Planning considerations – Examine all e-mail of suspected employees – Search Internet newsgroups or message boards – Initiate physical surveillance – Examine facility physical access logs for sensitive areas
- 52. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 52 Industrial Espionage Investigations • Planning considerations (cont’d) – Determine suspect location in relation to the vulnerable asset – Study the suspect’s work habits – Collect all incoming and outgoing phone logs • Steps to conducting an industrial espionage case – Gather all personnel assigned to the investigation and brief them on the plan – Gather resources to conduct the investigation
- 53. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 53 Industrial Espionage Investigations • Steps (cont’d) – Place surveillance systems at key locations – Discreetly gather any additional evidence – Collect all log data from networks and e-mail servers – Report regularly to management and corporate attorneys – Review the investigation’s scope with management and corporate attorneys
- 54. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 54 Interviews and Interrogations in High- Tech Investigations • Becoming a skilled interviewer and interrogator can take many years of experience • Interview – Usually conducted to collect information from a witness or suspect • About specific facts related to an investigation • Interrogation – Process of trying to get a suspect to confess
- 55. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 55 Interviews and Interrogations in High- Tech Investigations • Role as a computing investigator – To instruct the investigator conducting the interview on what questions to ask • And what the answers should be • Ingredients for a successful interview or interrogation – Being patient throughout the session – Repeating or rephrasing questions to zero in on specific facts from a reluctant witness or suspect – Being tenacious
- 56. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 56 Understanding Data Recovery Workstations and Software • Investigations are conducted on a computer forensics lab (or data-recovery lab) – In data recovery, the customer or your company just wants the data back • Computer forensics workstation – A specially configured PC – Loaded with additional bays and forensics software • To avoid altering the evidence use: – Write-blockers devices • Enable you to boot to Windows without writing data to the evidence drive
- 57. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 57 Setting Up Your Workstation for Digital Forensics • Basic requirements – A workstation running Windows XP or later – A write-blocker device – Digital forensics acquisition tool – Digital forensics analysis tool – Target drive to receive the source or suspect disk data – Spare PATA or SATA ports – USB ports
- 58. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 58 Setting Up your Workstation for Digital Forensics • Additional useful items – Network interface card (NIC) – Extra USB ports – FireWire 400/800 ports – SCSI card – Disk editor tool – Text editor tool – Graphics viewer program – Other specialized viewing tools
- 59. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 59 Conducting an Investigation • Gather resources identified in investigation plan • Items needed – Original storage media – Evidence custody form – Evidence container for the storage media – Bit-stream imaging tool – Forensic workstation to copy and examine your evidence – Securable evidence locker, cabinet, or safe
- 60. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 60 Gathering the Evidence • Avoid damaging the evidence • Steps – Meet the IT manager to interview him – Fill out the evidence form, have the IT manager sign – Place the evidence in a secure container – Carry the evidence to the computer forensics lab – Complete the evidence custody form – Secure evidence by locking the container
- 61. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 61 Understanding Bit-Stream Copies • Bit-stream copy – Bit-by-bit copy of the original storage medium – Exact copy of the original disk – Different from a simple backup copy • Backup software only copy known files • Backup software cannot copy deleted files, e-mail messages or recover file fragments • Bit-stream image – File containing the bit-stream copy of all data on a disk or partition – Also known as “image” or “image file”
- 62. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 62 Understanding Bit-stream Copies • Copy image file to a target disk that matches the original disk’s manufacturer, size and model
- 63. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 63 Acquiring an Image of Evidence Media • First rule of computer forensics – Preserve the original evidence • Conduct your analysis only on a copy of the data • Several vendors provide MS-DOS, Linux, and Windows acquisition tools – Windows tools require a write-blocking device when acquiring data from FAT or NTFS file systems
- 64. © Cengage Learning2015 Using ProDiscover Basic to Acquire a USB Drive Guide to Computer Forensics and Investigations Fifth Edition 64 • Create a work folder for data storage • Steps to perform an acquisition on a USB drive: – On the USB drive locate the write-protect switch and place the drive in write-protect mode – Start ProDiscover Basic – In the main window, click Action, Capture Image from the menu – Click the Source Drive drop-down list, and select the thumb drive
- 65. © Cengage Learning2015 Using ProDiscover Basic to Acquire a USB Drive Guide to Computer Forensics and Investigations Fifth Edition 65
- 66. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 66 Using ProDiscover Basic to Acquire a USB Drive • Steps (cont’d) – Click the >> button next to the Destination text box – Type your name in the Technician Name text box – ProDiscover Basic then acquires an image of the USB thumb drive – Click OK in the completion message box
- 67. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 67 Using ProDiscover Basic to Acquire a USB Drive
- 68. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 68 Analyzing Your Digital Evidence • Your job is to recover data from: – Deleted files – File fragments – Complete files • Deleted files linger on the disk until new data is saved on the same physical location • Tools can be used to retrieve deleted files – ProDiscover Basic
- 69. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 69 Analyzing Your Digital Evidence • Steps to analyze a USB drive – Start ProDiscover Basic – Create a new case – Type the project number – Add an Image File • Steps to display the contents of the acquired data – Click to expand Content View – Click All Files under the image filename path
- 70. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 70 Analyzing Your Digital Evidence • Steps to display the contents of the acquired data (cont’d) – Click letter1 to view its contents in the data area – In the data area, view contents of letter1 • Analyze the data – Search for information related to the complaint • Data analysis can be most time-consuming task
- 71. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 71 Analyzing Your Digital Evidence
- 72. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 72 Analyzing Your Digital Evidence • With ProDiscover Basic you can: – Search for keywords of interest in the case – Display the results in a search results window – Click each file in the search results window and examine its content in the data area – Export the data to a folder of your choice – Search for specific filenames – Generate a report of your activities
- 73. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 73 Analyzing Your Digital Evidence
- 74. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 74 Analyzing Your Digital Evidence
- 75. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 75 Analyzing Your Digital Evidence
- 76. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 76 Completing the Case • You need to produce a final report – State what you did and what you found • Include ProDiscover report to document your work • Repeatable findings – Repeat the steps and produce the same result • If required, use a report template • Report should show conclusive evidence – Suspect did or did not commit a crime or violate a company policy
- 77. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 77 Completing the Case • Keep a written journal of everything you do – Your notes can be used in court • Answer the six Ws: – Who, what, when, where, why, and how • You must also explain computer and network processes
- 78. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 78 Critiquing the Case • Ask yourself the following questions: – How could you improve your performance in the case? – Did you expect the results you found? Did the case develop in ways you did not expect? – Was the documentation as thorough as it could have been? – What feedback has been received from the requesting source?
- 79. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 79 Critiquing the Case • Ask yourself the following questions (cont’d): – Did you discover any new problems? If so, what are they? – Did you use new techniques during the case or during research?
- 80. © Cengage Learning2015 Summary • Digital forensics involves systematically accumulating and analyzing digital information for use as evidence in civil, criminal, and administrative cases • Investigators need specialized workstations to examine digital evidence • Public-sector and private-sector investigations differ; public-sector typically require search warrants before seizing digital evidence Guide to Computer Forensics and Investigations Fifth Edition 80
- 81. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 81 Summary • Always use a systematic approach to your investigations • Always plan a case taking into account the nature of the case, case requirements, and gathering evidence techniques • Both criminal cases and corporate-policy violations can go to court • Plan for contingencies for any problems you might encounter • Keep track of the chain of custody of your evidence
- 82. © Cengage Learning2015 Guide to Computer Forensics and Investigations Fifth Edition 82 Summary • Internet abuse investigations require examining server log data • For attorney-client privilege cases, all written communication should remain confidential • A bit-stream copy is a bit-by-bit duplicate of the original disk • Always maintain a journal to keep notes on exactly what you did • You should always critique your own work
Editor's Notes
- #1 Guide to Computer Forensics and Investigations Fifth Edition Chapter 1 Understanding The Digital Forensics Profession and Investigations
- #2 Objectives Describe the field of digital forensics Explain how to prepare computer investigations and summarize the difference between public-sector and private-sector investigations Explain the importance of maintaining professional conduct Describe how to prepare a digital forensics investigation by taking a systematic approach
- #3 Objectives Describe procedures for private-sector digital investigations Explain requirements for data recovery workstations and software Summarize how to conduct an investigation, including critiquing a case
- #4 An Overview of Digital Forensics Digital forensics The application of computer science and investigative procedures for a legal purpose involving the analysis of digital evidence after proper search authority, chain of custody, validation with mathematics, use of validated tools, repeatability, reporting, and possible expert presentation. In October 2012, an ISO standard for digital forensics was ratified - ISO 27037 Information technology - Security techniques
- #5 An Overview of Digital Forensics The Federal Rules of Evidence (FRE) was created to ensure consistency in federal proceedings Signed into law in 1973 Many states’ rules map to the FRE FBI Computer Analysis and Response Team (CART) was formed in 1984 to handle cases involving digital evidence By late 1990s, CART teamed up with Department of Defense Computer Forensics Laboratory (DCFL)
- #6 An Overview of Digital Forensics The Fourth Amendment to the U.S. Constitution protects everyone’s right to be secure from search and seizure Separate search warrants might not be necessary for digital evidence Every U.S. jurisdiction has case law related to the admissibility of evidence recovered from computers and other digital devices
- #7 Digital Forensics and Other Related Disciplines Investigating digital devices includes: Collecting data securely Examining suspect data to determine details such as origin and content Presenting digital information to courts Applying laws to digital device practices Digital forensics is different from data recovery Which involves retrieving information that was deleted by mistake or lost during a power surge or server crash
- #8 Digital Forensics and Other Related Disciplines Forensics investigators often work as part of a team, known as the investigations triad Figure 1-2 The investigation triad
- #9 Digital Forensics and Other Related Disciplines Vulnerability/threat assessment and risk management Tests and verifies the integrity of stand-along workstations and network servers Network intrusion detection and incident response Detects intruder attacks by using automated tools and monitoring network firewall logs Digital investigations Manages investigations and conducts forensics analysis of systems suspected of containing evidence
- #10 A Brief History of Digital Forensics By the early 1990s, the International Association of Computer Investigative Specialists (IACIS) introduced training on software for digital forensics IRS created search-warrant programs ASR Data created Expert Witness for Macintosh ILook is currently maintained by the IRS Criminal Investigation Division AccessData Forensic Toolkit (FTK) is a popular commercial product
- #11 Understanding Case Law Existing laws can’t keep up with the rate of technological change When statutes don’t exist, case law is used Allows legal counsel to apply previous similar cases to current one in an effort to address ambiguity in laws Examiners must be familiar with recent court rulings on search and seizure in the electronic environment
- #12 Developing Digital Forensics Resources To supplement your knowledge: Develop and maintain contact with computing, network, and investigative professionals Join computer user groups in both the pubic and private sectors Example: Computer Technology Investigators Network (CTIN) meets to discuss problems with digital forensics examiners encounter Consult outside experts
- #13 Preparing for Digital Investigations Digital investigations fall into two categories: Public-sector investigations Private-sector investigations Figure 1-5 Public-sector and private-sector investigations
- #14 Preparing for Digital Investigations Public-sector investigations involve government agencies responsible for criminal investigations and prosecution Fourth Amendment to the U.S. Constitution Restrict government search and seizure The Department of Justice (DOJ) updates information on computer search and seizure regularly Private-sector investigations focus more on policy violations
- #15 Understanding Law Enforcement Agency Investigations When conducting public-sector investigations, you must understand laws on computer-related crimes including: Standard legal processes Guidelines on search and seizure How to build a criminal case The Computer Fraud and Abuse Act was passed in 1986 Specific state laws were generally developed later
- #16 Following Legal Processes A criminal investigation usually begins when someone finds evidence of or witnesses a crime Witness or victim makes an allegation to the police Police interview the complainant and writes a report about the crime Report is processed and management decides to start an investigation or log the information in a police blotter Blotter is a historical database of previous crimes
- #17 Following Legal Processes Digital Evidence First Responder (DEFR) Arrives on an incident scene, assesses the situation, and takes precautions to acquire and preserve evidence Digital Evidence Specialist (DES) Has the skill to analyze the data and determine when another specialist should be called in to assist Affidavit - a sworn statement of support of facts about or evidence of a crime Must include exhibits that support the allegation
- #18 Understanding Private-Sector Investigations Private-sector investigations involve private companies and lawyers who address company policy violations and litigation disputes Example: wrongful termination Businesses strive to minimize or eliminate litigation Private-sector crimes can involve: E-mail harassment, falsification of data, gender and age discrimination, embezzlement, sabotage, and industrial espionage
- #19 Understanding Private-Sector Investigations Businesses can reduce the risk of litigation by publishing and maintaining policies that employees find easy to read and follow Most important policies define rules for using the company’s computers and networks Known as an “Acceptable use policy” Line of authority - states who has the legal right to initiate an investigation, who can take possession of evidence, and who can have access to evidence
- #20 Understanding Private-Sector Investigations Business can avoid litigation by displaying a warning banner on computer screens Informs end users that the organization reserves the right to inspect computer systems and network traffic at will Figure 1-8 A sample warning banner
- #21 Understanding Private-Sector Investigations Sample text that can be used in internal warning banners: Use of this system and network is for official business only Systems and networks are subject to monitoring at any time by the owner Using this system implies consent to monitoring by the owner Unauthorized or illegal users of this system or network will be subject to discipline or prosecution
- #22 Understanding Private-Sector Investigations Businesses are advised to specify an authorized requester who has the power to initiate investigations Examples of groups with authority Corporate security investigations Corporate ethics office Corporate equal employment opportunity office Internal auditing The general counsel or legal department
- #23 Understanding Private-Sector Investigations During private investigations, you search for evidence to support allegations of violations of a company’s rules or an attack on its assets Three types of situations are common: Abuse or misuse of computing assets E-mail abuse Internet abuse A private-sector investigator’s job is to minimize risk to the company
- #24 Understanding Private-Sector Investigations The distinction between personal and company computer property can be difficult with cell phones, smartphones, personal notebooks, and tablet computers Bring your own device (BYOD) environment Some companies state that if you connect a personal device to the business network, it falls under the same rules as company property
- #25 Maintaining Professional Conduct Professional conduct - includes ethics, morals, and standards of behavior An investigator must exhibit the highest level of professional behavior at all times Maintain objectivity Maintain credibility by maintaining confidentiality Investigators should also attend training to stay current with the latest technical changes in computer hardware and software, networking, and forensic tools
- #26 Preparing a Digital Forensics Investigation The role of digital forensics professional is to gather evidence to prove that a suspect committed a crime or violated a company policy Collect evidence that can be offered in court or at a corporate inquiry Investigate the suspect’s computer Preserve the evidence on a different computer Chain of custody Route the evidence takes from the time you find it until the case is closed or goes to court
- #27 An Overview of a Computer Crime Computers can contain information that helps law enforcement determine: Chain of events leading to a crime Evidence that can lead to a conviction Law enforcement officers should follow proper procedure when acquiring the evidence Digital evidence can be easily altered by an overeager investigator A potential challenge: information on hard disks might be password protected so forensics tools may be need to be used in your investigation
- #28 An Overview of a Company Policy Violation Employees misusing resources can cost companies millions of dollars Misuse includes: Surfing the Internet Sending personal e-mails Using company computers for personal tasks
- #29 Taking a Systematic Approach Steps for problem solving Make an initial assessment about the type of case you are investigating Determine a preliminary design or approach to the case Create a detailed checklist Determine the resources you need Obtain and copy an evidence drive
- #30 Taking a Systematic Approach Steps for problem solving (cont’d) Identify the risks Mitigate or minimize the risks Test the design Analyze and recover the digital evidence Investigate the data you recover Complete the case report Critique the case
- #31 Assessing the Case Systematically outline the case details Situation Nature of the case Specifics of the case Type of evidence Known disk format Location of evidence Based on these details, you can determine the case requirements
- #32 Planning Your Investigation A basic investigation plan should include the following activities: Acquire the evidence Complete an evidence form and establish a chain of custody Transport the evidence to a computer forensics lab Secure evidence in an approved secure container
- #33 Planning Your Investigation A basic investigation plan (cont’d): Prepare your forensics workstation Retrieve the evidence from the secure container Make a forensic copy of the evidence Return the evidence to the secure container Process the copied evidence with computer forensics tools
- #34 Planning Your Investigation An evidence custody form helps you document what has been done with the original evidence and its forensics copies Also called a chain-of-evidence form Two types Single-evidence form Lists each piece of evidence on a separate page Multi-evidence form
- #35 Planning Your Investigation Figure 1-10 A sample multi-evidence from used on a private-sector environment
- #36 Planning Your Investigation Figure 1-11 A single-evidence form
- #37 Securing Your Evidence Use evidence bags to secure and catalog the evidence Use computer safe products when collecting computer evidence Antistatic bags Antistatic pads Use well padded containers Use evidence tape to seal all openings CD drive bays Insertion slots for power supply electrical cords and USB cables
- #38 Securing Your Evidence Write your initials on tape to prove that evidence has not been tampered with Consider computer specific temperature and humidity ranges Make sure you have a safe environment for transporting and storing it until a secure evidence container is available
- #39 Procedures for Private-Sector High-Tech Investigations As an investigator, you need to develop formal procedures and informal checklists To cover all issues important to high-tech investigations Ensures that correct techniques are used in an investigation
- #40 Employee Termination Cases The majority of investigative work for termination cases involves employee abuse of corporate assets Incidents that create a hostile work environment are the predominant types of cases investigated Viewing pornography in the workplace Sending inappropriate e-mails Organizations must have appropriate policies in place
- #41 Internet Abuse Investigations To conduct an investigation you need: Organization’s Internet proxy server logs Suspect computer’s IP address Suspect computer’s disk drive Your preferred computer forensics analysis tool
- #42 Internet Abuse Investigations Recommended steps Use standard forensic analysis techniques and procedures Use appropriate tools to extract all Web page URL information Contact the network firewall administrator and request a proxy server log Compare the data recovered from forensic analysis to the proxy server log Continue analyzing the computer’s disk drive data
- #43 E-mail Abuse Investigations To conduct an investigation you need: An electronic copy of the offending e-mail that contains message header data If available, e-mail server log records For e-mail systems that store users’ messages on a central server, access to the server Access to the computer so that you can perform a forensic analysis on it Your preferred computer forensics analysis tool
- #44 E-mail Abuse Investigations Recommended steps Use the standard forensic analysis techniques Obtain an electronic copy of the suspect’s and victim’s e-mail folder or data For Web-based e-mail investigations, use tools such as FTK’s Internet Keyword Search option to extract all related e-mail address information Examine header data of all messages of interest to the investigation
- #45 Attorney-Client Privilege Investigations Under attorney-client privilege (ACP) rules for an attorney You must keep all findings confidential Many attorneys like to have printouts of the data you have recovered You need to persuade and educate many attorneys on how digital evidence can be viewed electronically You can also encounter problems if you find data in the form of binary files
- #46 Attorney-Client Privilege Investigations Steps for conducting an ACP case Request a memorandum from the attorney directing you to start the investigation Request a list of keywords of interest to the investigation Initiate the investigation and analysis For disk drive examinations, make two bit-stream images using different tools for each image Compare hash signatures on all files on the original and re-created disks
- #47 Attorney-Client Privilege Investigations Steps for conducting an ACP case (cont’d) Methodically examine every portion of the disk drive and extract all data Run keyword searches on allocated and unallocated disk space For Windows OSs, use specialty tools to analyze and extract data from the Registry For binary data files such as CAD drawings, locate the correct software product For unallocated data recovery, use a tool that removes or replaces nonprintable data
- #48 Attorney-Client Privilege Investigations Steps for conducting an ACP case (cont’d) Consolidate all recovered data from the evidence bit-stream image into folders and subfolders Other guidelines Minimize written communications with the attorney Any documentation written to the attorney must contain a header stating that it’s “Privileged Legal Communication—Confidential Work Product” Assist the attorney and paralegal in analyzing data
- #49 Industrial Espionage Investigations All suspected industrial espionage cases should be treated as criminal investigations Staff needed Computing investigator who is responsible for disk forensic examinations Technology specialist who is knowledgeable of the suspected compromised technical data Network specialist who can perform log analysis and set up network sniffers Threat assessment specialist (typically an attorney)
- #50 Industrial Espionage Investigations Guidelines when initiating an investigation Determine whether this investigation involves a possible industrial espionage incident Consult with corporate attorneys and upper management Determine what information is needed to substantiate the allegation Generate a list of keywords for disk forensics and sniffer monitoring List and collect resources for the investigation
- #51 Industrial Espionage Investigations Guidelines (cont’d) Determine goal and scope of the investigation Initiate investigation after approval from management Planning considerations Examine all e-mail of suspected employees Search Internet newsgroups or message boards Initiate physical surveillance Examine facility physical access logs for sensitive areas
- #52 Industrial Espionage Investigations Planning considerations (cont’d) Determine suspect location in relation to the vulnerable asset Study the suspect’s work habits Collect all incoming and outgoing phone logs Steps to conducting an industrial espionage case Gather all personnel assigned to the investigation and brief them on the plan Gather resources to conduct the investigation
- #53 Industrial Espionage Investigations Steps (cont’d) Place surveillance systems at key locations Discreetly gather any additional evidence Collect all log data from networks and e-mail servers Report regularly to management and corporate attorneys Review the investigation’s scope with management and corporate attorneys
- #54 Interviews and Interrogations in High-Tech Investigations Becoming a skilled interviewer and interrogator can take many years of experience Interview Usually conducted to collect information from a witness or suspect About specific facts related to an investigation Interrogation Process of trying to get a suspect to confess
- #55 Interviews and Interrogations in High-Tech Investigations Role as a computing investigator To instruct the investigator conducting the interview on what questions to ask And what the answers should be Ingredients for a successful interview or interrogation Being patient throughout the session Repeating or rephrasing questions to zero in on specific facts from a reluctant witness or suspect Being tenacious
- #56 Understanding Data Recovery Workstations and Software Investigations are conducted on a computer forensics lab (or data-recovery lab) In data recovery, the customer or your company just wants the data back Computer forensics workstation A specially configured PC Loaded with additional bays and forensics software To avoid altering the evidence use: Write-blockers devices Enable you to boot to Windows without writing data to the evidence drive
- #57 Setting Up Your Workstation for Digital Forensics Basic requirements A workstation running Windows XP or later A write-blocker device Digital forensics acquisition tool Digital forensics analysis tool Target drive to receive the source or suspect disk data Spare PATA or SATA ports USB ports
- #58 Setting Up your Workstation for Digital Forensics Additional useful items Network interface card (NIC) Extra USB ports FireWire 400/800 ports SCSI card Disk editor tool Text editor tool Graphics viewer program Other specialized viewing tools
- #59 Conducting an Investigation Gather resources identified in investigation plan Items needed Original storage media Evidence custody form Evidence container for the storage media Bit-stream imaging tool Forensic workstation to copy and examine your evidence Securable evidence locker, cabinet, or safe
- #60 Gathering the Evidence Avoid damaging the evidence Steps Meet the IT manager to interview him Fill out the evidence form, have the IT manager sign Place the evidence in a secure container Carry the evidence to the computer forensics lab Complete the evidence custody form Secure evidence by locking the container
- #61 Understanding Bit-Stream Copies Bit-stream copy Bit-by-bit copy of the original storage medium Exact copy of the original disk Different from a simple backup copy Backup software only copy known files Backup software cannot copy deleted files, e-mail messages or recover file fragments Bit-stream image File containing the bit-stream copy of all data on a disk or partition Also known as “image” or “image file”
- #62 Understanding Bit-stream Copies Copy image file to a target disk that matches the original disk’s manufacturer, size and model Figure 1-12 Transfer of data from original to image to target
- #63 Acquiring an Image of Evidence Media First rule of computer forensics Preserve the original evidence Conduct your analysis only on a copy of the data Several vendors provide MS-DOS, Linux, and Windows acquisition tools Windows tools require a write-blocking device when acquiring data from FAT or NTFS file systems
- #64 Using ProDiscover Basic to Acquire a USB Drive Create a work folder for data storage Steps to perform an acquisition on a USB drive: On the USB drive locate the write-protect switch and place the drive in write-protect mode Start ProDiscover Basic In the main window, click Action, Capture Image from the menu Click the Source Drive drop-down list, and select the thumb drive
- #65 Using ProDiscover Basic to Acquire a USB Drive Figure 1-14 The Capture Image dialog box
- #66 Using ProDiscover Basic to Acquire a USB Drive Steps (cont’d) Click the >> button next to the Destination text box Type your name in the Technician Name text box ProDiscover Basic then acquires an image of the USB thumb drive Click OK in the completion message box
- #67 Using ProDiscover Basic to Acquire a USB Drive Figure 1-15 The complement Capture Image dialog box
- #68 Analyzing Your Digital Evidence Your job is to recover data from: Deleted files File fragments Complete files Deleted files linger on the disk until new data is saved on the same physical location Tools can be used to retrieve deleted files ProDiscover Basic
- #69 Analyzing Your Digital Evidence Steps to analyze a USB drive Start ProDiscover Basic Create a new case Type the project number Add an Image File Steps to display the contents of the acquired data Click to expand Content View Click All Files under the image filename path
- #70 Analyzing Your Digital Evidence Steps to display the contents of the acquired data (cont’d) Click letter1 to view its contents in the data area In the data area, view contents of letter1 Analyze the data Search for information related to the complaint Data analysis can be most time-consuming task
- #71 Analyzing Your Digital Evidence Figure 1-19 Selecting a file in the work area and viewing its contents in the data area
- #72 Analyzing Your Digital Evidence With ProDiscover Basic you can: Search for keywords of interest in the case Display the results in a search results window Click each file in the search results window and examine its content in the data area Export the data to a folder of your choice Search for specific filenames Generate a report of your activities
- #73 Analyzing Your Digital Evidence Figure 1-20 Entering a keyboard in the Search dialog box
- #74 Analyzing Your Digital Evidence Figure 1-21 The search results pane
- #75 Analyzing Your Digital Evidence Figure 1-23 A ProDiscover report
- #76 Completing the Case You need to produce a final report State what you did and what you found Include ProDiscover report to document your work Repeatable findings Repeat the steps and produce the same result If required, use a report template Report should show conclusive evidence Suspect did or did not commit a crime or violate a company policy
- #77 Completing the Case Keep a written journal of everything you do Your notes can be used in court Answer the six Ws: Who, what, when, where, why, and how You must also explain computer and network processes
- #78 Critiquing the Case Ask yourself the following questions: How could you improve your performance in the case? Did you expect the results you found? Did the case develop in ways you did not expect? Was the documentation as thorough as it could have been? What feedback has been received from the requesting source?
- #79 Critiquing the Case Ask yourself the following questions (cont’d): Did you discover any new problems? If so, what are they? Did you use new techniques during the case or during research?
- #80 Summary Digital forensics involves systematically accumulating and analyzing digital information for use as evidence in civil, criminal, and administrative cases Investigators need specialized workstations to examine digital evidence Public-sector and private-sector investigations differ; public-sector typically require search warrants before seizing digital evidence
- #81 Summary Always use a systematic approach to your investigations Always plan a case taking into account the nature of the case, case requirements, and gathering evidence techniques Both criminal cases and corporate-policy violations can go to court Plan for contingencies for any problems you might encounter Keep track of the chain of custody of your evidence
- #82 Summary Internet abuse investigations require examining server log data For attorney-client privilege cases, all written communication should remain confidential A bit-stream copy is a bit-by-bit duplicate of the original disk Always maintain a journal to keep notes on exactly what you did You should always critique your own work