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Emerging Problems in Forensic Computing Peter Sommer

Emerging Problems in Forensic Computing Peter Sommer. Computer Evidence…. Computer Evidence: < 45 years Computer Forensics: < 15 years Data from computers can be reliably preserved and presented in court Deleted data can be recovered Events can be reconstructed

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Emerging Problems in Forensic Computing Peter Sommer

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  1. Emerging Problems in Forensic Computing Peter Sommer

  2. Computer Evidence…. Computer Evidence: < 45 years Computer Forensics: < 15 years • Data from computers can be reliably preserved and presented in court • Deleted data can be recovered • Events can be reconstructed • Intentions can be inferred Lots of good products and procedures to support …. Apparently quite a success story

  3. hacking fraud paedophiliac rings defamation immigration fraud narcotics trafficking credit card cloning software piracy terrorism electoral law obscene publication perjury forgery murder sexual harassment data theft – industrial espionage divorce Computer Forensics ….deployed in:

  4. Computer Evidence... ...is like any other evidence, it must be: • admissible • authentic • accurate • complete • convincing to juries

  5. Computer Evidence... ...is different from other evidence - computer data: • can change from moment to moment within a computer and along a transmission line • can be easily altered without trace • can be changed during evidence collection

  6. Computer Evidence... ...is different from other evidence: • much immediate computer evidence cannot be read by humans • many exhibits are print-out derived from primary electronic material • computers create evidence as well as record it • rate of change of technology

  7. Computer Evidence... ...creates as many opportunities as it provides threats: • many more commercial transactions are recorded • it is much easier to trace a person’s history and activities • computer-assisted investigation methods become possible...

  8. Mainframes PCs LANs Internet Solid State Memory Brief History of Computer Evidence

  9. Mainframes Controlled print-out Early problem of admissibility How do we test reliability? Brief History of Computer Evidence

  10. PCs Can be seized Disks can be “imaged” and then analysed “Real” evidence can we trust the “imaging”? Quality of inferences Brief History of Computer Evidence

  11. LANs Too complex to seize How do we ensure completeness? How do we ensure reliability? Brief History of Computer Evidence

  12. Internet We can seize individual PCs, Internet History and caches Use of newsgroups, IRC, P2P Email Deleted material may be recoverable Brief History of Computer Evidence

  13. Internet we may also rely on: evidence from remote computers evidence from investigators’ computers intercepts Brief History of Computer Evidence But the Internet crosses national boundaries – and different policing and legal systems …

  14. Solid State Memory Cameras, PDAs, MP3 players, mobile phones How do you recover data without altering it? Brief History of Computer Evidence

  15. Getting hold of the Evidence • Warrants for law enforcement • Disclosure / Discovery for defence (and in civil proceedings) • Most of these are jurisdiction-specific (ie one country at a time) • Many cyber-crimes are international • CyberCrime Treaty • Detection of crime / terrorism vs national sovereignty

  16. Getting hold of the Evidence • What happens when law enforcement is afraid that disclosure of methods might impact • Current investigations? • Future investigations, where criminals may take evasive action? • But can we allow evidence we can’t test? • Defendant should be allowed “parity of arms”

  17. Forensic procedures.. • Freezing the scene • a formal process • imaging • Maintaining continuity of evidence • controlled copying • controlled print-out • Contemporaneous notes > witness statements

  18. Forensic procedures.. authenticity, accuracy, completeness, admissibility • repeatability • independent checking / auditing • well-defined procedures • check-lists • anticipation of criticism • novel scientific methods?

  19. Disk Forensics • First products appear end 1980s • Disk “imaging” / bit-copy • Subsequent analysis • Report Creation • “Tool-box” / “Integrated” • DIBS / Safeback / Maresware / NTI Authentec / EnCase / AccessData FTK/ ILOOK • ACPO Good Practice Guidelines

  20. Direct Results UK Court of Appeal re-interpretations of “making” in s 1(1)(a) Protection of Children Act, 1978 – Bowden, Atkins, Goodland, Smith, Jayston • depends on accurate forensic examination of computer hard-disks • to determine deliberate copying, deliberate searching, deliberate downloading, • inferring states of mind and intention

  21. PDAs, Cameras, Solid State Memory How do we preserve Evidence?

  22. Computer Forensics …. But this has been mostly about DISK forensics, specifically disks in PCs What about: • evidence from large systems? • evidence from remote sites? • evidence from networks? • evidence from data eavesdropped in transmission?

  23. Controlled print-out from large mainframes eg from banks, larger companies, government organisations …. • we can’t “image” a clearing bank • how do demonstrate the system is working properly? • what forms might “improper working” take? • is the evidence complete? • how can the other side test?

  24. Controlled print-out from large complex systems • how do demonstrate the system is working properly? • what forms might “improper working” take? • is the evidence complete? • how can the other side test?

  25. File from remote computer to show: fraudulent offer, incitement, defamation, obscene publication Incriminating file Investigator PC Dial-up, leased line, network, Internet

  26. File from remote computer • But how do you demonstrate that the download is “reliable”? • admissible • authentic • accurate • complete • What happens if you are downloading from a www site? • caches - local and at ISP • dynamic pages, etc etc, XML etc

  27. Customer information from ISPs/CSPs • customer identity • time and duration of connection • ?? IP address assigned ?? (RADIUS logs) • reliability / testing ??

  28. Interception • material comes from ISPs/CSPs, whose technical co-operation is needed • conditions of warrant issue must be met • communications data (who is connected to what, when and for how long) plus content (what is said or transmitted) can both be collected • reliability / testing / disclosure ??

  29. Network Forensics • Evidence collected “in normal operations” • logs • IDS outputs • Evidence collected under specific surveillance • extended logs • “sniffers” etc

  30. Network Forensics How much of this is forensically reliable? How does defence test? (parity of arms) Problems of disclosure • specific methods • network topology / configuration • proprietary tools

  31. Target logs,files Pryce’s HDD ISP Info, logs Unix logs, Monitoring progs Target logs,files Phone Logs Target logs,files Network Monitor Logs

  32. Computer Intrusion • covers covert entry into computers • installation of keystroke monitors, etc • legally tricky because relatively untried - Scarfo • evidence from suspect’s computers has been compromised and may therefore be questioned

  33. “Remote Management Tools” Back Orifice Sub Seven Hack’a’Tack D.I.R.T Magic Lantern SpectorSoft Pro Computer Intrusion But investigator has the opportunity, covertly to alter data – or may be doing so inadvertently

  34. Conclusions The high standards in disk forensics are not matched in other areas: • Records from big computers and networks • Records of web activity • Integrity of log files • Solid State Memory • Integrity of products of interception / surveillance activities

  35. Conclusions Forensic Computing / Computer Forensics has developed outside the main traditions of “Forensic Science” Speed of change makes “peer reviewed” testing of methods difficult • do we ignore new modes of crime because we haven’t tested our forensic tools? • do we expose juries to lengthy technical disputes between experts?

  36. Conclusions Constant novelty: • Forensic computing tracks all changes in technology – and social structures and conventions • Insufficient time for usual cycle of peer-reviewed publication of new and tested forensic techniques and discoveries • The greater the novelty, the greater the need for testability

  37. Conclusions Problems of expert evidence: • How do we explain accurately difficult stuff to lay audiences? • Specialist juries? • Pre-trial meetings between experts? • Certification of experts? • Single Court-appointed experts? All of these have problems…

  38. Peeking into the Future … • 3G mobile phones • Mobile high-speed terminals – currently we have no equivalent of disk forensics for these • New Microsoft Operating Systems • Encryption only under the control of the user – a branch of Digital Rights Management • Storage spread over multiple remote locations – how will law enforcement get warrants to seize?

  39. Emerging Problems in Forensic Computing Peter Sommer

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