1. Digital Forensics and Digital Detective Work

2. 2 Objectives Recognize the role e-evidence plays in physical, or violent, and digital item crimes Describe the basic steps in a digital forensics investigation Identify the legal and ethical issues affecting evidence search and seizure Identify the types of challenges to the admissibility of e-evidence

3. 3 Objectives (Cont.) Understand how criminals’ motives can help in crime detection and investigation Explain chain of custody Explain why acceptable methods for computer forensics investigations and e- discovery are still emerging

4. 4 Introduction Digital forensics investigators are “detectives of the digital world.” This ppt introduces you to the generally accepted methods used in digital forensics; computer architecture, the Internet, other digital devices, and the types of evidence these trails leave behind.

5. 5 E-Evidence Trails and Hidden Files Computers are routinely used to plan and coordinate many types of crimes Computer activities leave e-evidence trails  File-wiping software can be used to delete and overwrite data (i.e. Privacy Suite from CyberScrub)  File-wiping process takes time and expertise Many e-evidence traces can be found by showing hidden files on a computer

6. 6 Knowing What to Look For Technical knowledge of how data and metadata are stored will determine what e- evidence is found For this reason, technical knowledge of investigators must keep pace with evolving data storage devices

7. 7 Knowing What to Look for (Cont.) Three cases illustrate importance of technical knowledge:  Dr. Harold Shipman (serial killer responsible for at least 236 murders from 75 to 98) modified medical records to hide evidence of murder; date stamp revealed records were fraudulent  Employees made online purchases with customer credit cards; hidden HTML code revealed fraud  Neil Entwhistle killed his wife and child; cache showed Internet sites that described how to kill people

8. 8 The Five Ws Answering the 5 Ws helps in criminal investigations:  Who  What  Where  When  Why

9. 9 In Practice: PDA Forensics PDA forensics are being used frequently in homicide investigations and white collar crimes Examples:  Danielle van Dam murder, February 2002 (police examined four hard drives and a Palm Pilot PDA of a person who was then convicted)  Doctors found to be falsely billing for Medicaid and Medicare patients that were never seen

10. 10 Preserving Evidence Preserving evidence is critical in order to use the evidence in a legal defense or prosecution Scientific methods must be used in order to preserve the integrity of the evidence collected

11. 11 Digital Forensics Process Consistent with other scientific research, a digital forensics investigation is a process There are five stages to the process:  Preparation (investigator and tools, not the data)  Collection (the data)  Examination  Analysis  Reporting

12. 12 Admissibility of Evidence Goal of an investigation: collect evidence using accepted methods so that the evidence is accepted in the courtroom and admitted as evidence in the trial Judge’s acceptance of evidence is called admission of evidence

13. 13 Admissibility of Evidence (Cont.) Evidence admissibility requires legal search and seizure and chain of custody Chain of custody must include:  Where the evidence was stored  Who had access to the evidence  What was done to the evidence In some cases, it may be more important to protect operations than obtain admissible evidence

14. © Pearson Education Computer Forensics: Principles and Practices 14 In Practice: CD Universe Prosecution Failure Attempted extortion involving credit card numbers by “Maxim” Six months after the incident, Maxim still could not be found Evidence was compromised by FBI and security firms who may have used original data rather than a forensic copy (changed the last-access dates)

15. 15 Digital Signatures and Profiling Digital signature left by serial killer  Dennis L. Rader revealed as “BTK”  Hidden electronic code on disk led to church where he had access to a computer Digital profiling of crime suspects  E-evidence can supply patterns of behavior or imply motives  Evidence can include information stored on computers, e-mail, cell phone data, and wiretaps

16. 16 Crimes Solved Using Forensics CriminalType of CrimeType of E-Evidence Dennis RaderSerial killerDeleted files on a floppy disk used by the criminal at his church’s computer Lee Boyd Malvo, John Allen Muhammad SnipersDigital recordings on a device in suspects’ car Lisa MontgomeryMurder and fetus- kidnapping E-mail communication between the victim and criminal—tracing an IP address to a computer at criminal’s home (Continued)

17. 17 Crimes Solved Using Forensics (Cont.) CriminalType of CrimeType of E-Evidence David A. WesterfieldMurderFiles on four computer hard drives and a PDA Scott PetersonDouble murderGPS data from his car and cell phone; Internet history Alejandro AvilaRape and murderE-evidence of child pornography on his computer Zacarias MoussaouiTerrorismE-mail, files from his computers

18. 18 Forensics Investigation Methods  Protect the suspect system from any possible alteration, damage, data corruption, or virus introduction  Discover all files  Recover deleted files  Reveal contents of hidden files  Access protected or encrypted files  Use steganalysis to identify hidden data  Analyze data in unallocated and slack space  Print an analysis of the system  Provide an opinion of the system layout  Provide expert testimony or consultation Methods used by investigators must achieve these objectives:

19. 19 Unallocated Space and File Slack Unallocated space: space that is not currently used to store an active file but may have stored a file previously File slack: space that remains if a file does not take up an entire sector Unallocated space and slack space can contain important information for an investigator

20. © Pearson Education Computer Forensics: Principles and Practices 20 File System Most commonly used storage device: hard disk or CD- ROM Hard disk – see next two slides File – a digital document which has a file name and metadata File content, e.g. the text and figures in a Word document Metadata – data that describe data, e.g. size, time, user ID, access permission, etc.(useful in DF) Directory – folder that contains sub-directories and files File systems - Is a method of storing and organizing files and data to make it easy to find and access them FAT (for older versions of Windows), NTFS (for newer versions of Windows, ext2, ext3, ext4 (latest file system for Linux) FATNTFSext4

21. 21 Structure of a Hard Disk (A) Track – circular path on the surface of a disk where information is magnetically recorded and read. (B) Geometrical sector – a subdivision of tracks

22. 22 Structure of a Hard Disk cont. (C) (Track) Sector – a sector on a track storing fixed amount of data (e.g. 512 bytes) (D) Cluster – the unit disk space allocation for files and directories. Cluster (not sector) is the smallest unit for file/directory allocation, and it contains contiguous groups of sectors, e.g. A 4 KB cluster contains 8 512-byte sectors.

23. 23 NYS Police Forensic Procedures StageToolsDiscussion Seizing the computer NoneComputer and technology are seized under the rules, evidence, and the warrant that they hold. Evidence is transported and secured at the Forensic Investigation Center (FIC). BackupSafeback, Expert Witness, Snapback Backup is done using one of the listed tools. A case file is created on an optical disk (CD). Evidence extraction Expert WitnessThe FIC is moving much of the investigative process to Expert Witness. Traditional searches are done currently to find and extract evidence. (Continued)

24. 24 NYS Police Forensic Procedures (Cont.) StageToolsDiscussion Case creationExpert WitnessThe case creation process allows the extracted information to be placed in a case file, on a floppy disk, hard disk, or removable media. Case analysisNoneInvestigators use experience and training to search the computer evidence for documents, deleted files, images, e-mail, slack space, etc., that will help in the case. Correlation of computer events NoneTimeline, order of events, related activities, and contradictory evidence are the components of this stage. (Continued)

25. 25 NYS Police Forensic Procedures (Cont.) StageToolsDiscussion Correlation of noncomputer events NonePhone records, credit card receipts, eyewitness testimony, etc. are manually sorted and correlated. Case presentation Standard OfficeFinally, the information that has been extracted, analyzed, and correlated is put together in a form ready for presentation to a judge or jury.

26. 26 Challenges to Evidence Criminal trials may be preceded by a suppression hearing  This hearing determines admissibility or suppression of evidence  Judge determines whether Fourth Amendment has been followed in search and seizure of evidence. The success of any investigation depends on proper and ethical investigative procedures

27. 27 Search Warrants Investigators generally need a search warrant to search and seize evidence Law officer must prepare an affidavit that describes the basis for probable cause—a reasonable belief that a person has committed a crime Search warrant gives an officer only a limited right to violate a citizen’s privacy

28. 28 Search Warrants (Cont.) Two reasons a search can take place without a search warrant:  The officer may search for and remove any weapons that the arrested person may use to escape or resist arrest  The officer may seize evidence in order to prevent its destruction or concealment

29. 29 In Practice: A Terrorist’s Trial FBI agents attempted to get permission to search Moussaoui’s laptop but permission was denied on grounds they had not proved probable cause Events on September 11 provided enough evidence for a search warrant, but by this time it was too late to access e-mail accounts that might have provided important data

30. 30 Motives for Cybercrimes Finding the motive—the “why” of the crime— can help in an investigation Possible motives:  Financial gain, including extortion and blackmail  Cover up a crime  Remove incriminating information or correspondence  Steal goods or services without having to pay for them  Industrial espionage

31. 31 Categories of Cybercrimes Computer is the crime target Computer is the crime instrument Computer is incidental to traditional crimes New crimes generated by the prevalence of computers

32. 32 Chain of Custody Procedures Handling of e-evidence must follow the three C’s of evidence: care, control, and chain of custody Chain of custody procedures  Keep an evidence log that shows when evidence was received and seized, and where it is located  Record dates if items are released to anyone  Restrict access to evidence  Place original hard drive in an evidence locker  Perform all forensics on a mirror-image copy, never on the original data

33. 33 Report Procedures All reports of the investigation should be prepared with the understanding that they will be read by others The investigator should never comment on the guilt or innocence of a suspect or suspects or their affiliations

34. 34 Digital Forensics Investigator’s Responsibilities Investigate and/or review current digital and digital- mediated crimes Maintain objectivity when seizing and investigating computers, suspects, and support staff Conduct all forensics investigations consistently with generally accepted procedures and federal rules of evidence and discovery Keep a log of activities undertaken to stay current in the search, seizure, and processing of e-evidence

35. 35 Summary Computers and the Internet have contributed to traditional and computer crimes Effective forensic investigation requires any technology that tracks what was done, who did it, and when Images or exact copies of the digital media being investigated need to be examined by trained professionals

36. 36 Summary (Cont.) There are several legal and ethical issues of evidence seizure, handling, and investigation New federal rules and laws regulate forensic investigations The need for e-evidence has led to a new area of criminal investigation, namely digital forensics This field is less than 20 years old

37. 37 Summary (Cont.) Digital forensics depends on an understanding of technical and legal issues Greatest legal issue in digital forensics is the admissibility of evidence in criminal cases Digital forensics investigators identify, gather, extract, protect, preserve, and document computer and other e-evidence using acceptable methods

38. 38 Summary (Cont.) Laws of search and seizure, as they relate to electronic equipment, must be followed Failure to follow proper legal procedure will result in evidence being ruled inadmissible in court