Deciphering Digital Forensics: Unraveling the Process of Evidence Collection

Research Wing
Research Wing
Innovation and Research
PUBLISHED ON
May 10, 2024
10

Introduction:

Welcome to the third edition of our blog on digital forensics series. In our previous blog we discussed the difference between copying, cloning, and imaging in the context of Digital Forensics, and found out why imaging is a better process. Today we will discuss the process of evidence collection in Digital Forensics. The whole process starts with making sure the evidence collection team has all necessary tools required for the task.

Investigating Tools and Equipment:

Below are some mentioned tools that the team should carry with them for a successful evidence collection:

  • Anti-static bags
  • Faraday bags
  • Toolkit having screwdrivers(nonmagnetic), scissors, pins, cutters, forceps, clips etc.
  • Rubber gloves
  • Incident response toolkit (Software)
  • Converter/Adapter: USB, SATA, IDE, SCSI
  • Imaging software
  • Volatile data collection tools (FTK Imager, Magnet Forensics RAM Capture)
  • Pens, permanent markers
  • Storage containers
  • Batteries
  • Video cameras
  • Note/sketch pads
  • Blank storage media
  • Write-Blocker device
  • Labels
  • Crime scene security tapes
  • Camera

What sources of Data are necessary for Digital Evidence?

  • Hard-Drive (Desktop, Laptop, External, Server)
  • Flash Drive
  • SD Cards
  • Floppy Disks
  • Optical Media (CD, DVD)
  • CCTV/DVR
  • Internal Storage of Mobile Device
  • GPS (Mobile/Car)
  • Call Site Track (Towers)
  • RAM

Evidence Collection

The investigators encounter two primary types of evidence during the course of gathering evidence: non-electronic and electronic evidence.

The following approaches could be used to gather non-electronic evidence:

  • In the course of looking into electronic crimes, recovering non-electronic evidence can be extremely important.  Be cautious to make sure that this kind of evidence is retrieved and kept safe. Items that may be relevant to a later review of electronic evidence include passwords, papers or printouts, calendars, literature, hardware and software manuals, text or graphical computer printouts, and photos.  These items should be secured and kept for further examination.
  • They are frequently found close to the computer or other related hardware.  Locating, securing, and preserving all evidence is required by departmental procedures.

Three scenarios arise for the collection of digital evidence from computers: 

Situation 1: The desktop is visible, and the monitor is on.

  • Take a picture of the screen and note the data that is visible. 
  • Utilize tools for memory capturing to gather volatile data.
  • Look for virtual disks. If so, gather mounted data's logical copies.
  • Give each port and connection a label.
  • Take a picture of them.
  • Turn off network access to stop remote access.
  • Cut off the power or turn it off.
  • Locate and disconnect the hard drive by opening the CPU chassis.
  • Take all evidence and place it in anti-magnetic (Faraday) bags.
  • Deliver the evidence to the forensic lab.
  • Keep the chain of custody intact.

Situation 2: The monitor is turned on, but it either has a blank screen (sleep mode) or an image for the screensaver.

  • Make a small mouse movement (without pressing buttons). The work product should appear on the screen, or it should ask for a password.
  • If moving the mouse does not result in a change to the screen, stop using the mouse and stop all keystrokes.
  • Take a picture of the screen and note the data that is visible.
  • Use memory capturing tools to gather volatile data (always use a write blocker to prevent manipulation during data collection).
  • Proceed further in accordance with Situation 1.

Situation 3: The Monitor Is Off

  • Write down the "off" status.
  • After turning on the monitor, check to see if its status matches that of situations 1 or 2 above, and then take the appropriate action.
  • Using a phone modem, cable, confirm that you are connected to the outside world. Try to find the phone number if there is a connection to the phone.
  • To protect evidence, take out the floppy disks that might be there, package each disk separately, and label the evidence.  Put in a blank floppy disk or a seizure disk, if one is available. Avoid touching the CD drive or taking out CDs.
  • Cover the power connector and every drive slot with tape.
  • Note the serial number, make, and model.
  • Take a picture of the computer's connections and make a diagram with the relevant cables.
  • To enable precise reassembly at a later date, label all connectors and cable ends, including connections to peripheral devices. Put "unused" on any connection ports that are not in use.  Recognize docking stations for laptop computers in an attempt to locate additional storage media.
  • All evidence should be seized and placed in anti-magnetic (Faraday) bags.
  • All evidence should be seized and placed in anti-magnetic (Faraday) bags.
  • Put a tag or label on every bag.
  • Deliver the evidence to the forensic lab.
  • Keep the chain of custody intact. 

Following the effective gathering of data, the following steps in the process are crucial: data packaging, data transportation, and data storage.

The following are the steps involved in data packaging, transportation, and storage:

Packaging:

  • Label every computer system that is gathered so that it can be put back together exactly as it was found

When gathering evidence at a scene of crime,

  • Before packing, make sure that every piece of evidence has been appropriately  labeled and documented.
  • Latent or trace evidence requires particular attention, and steps should be taken to preserve it.
  • Use paper or antistatic plastic bags for packing magnetic media to prevent static electricity. Do not use materials like regular plastic bags (instead use faraday bags) that can cause static electricity. 
  • Be careful not to bend, fold, computer media like tapes, or CD-ROM.
  • Make sure that the labels on every container used to store evidence are correct.

Transporting

  • Make sure devices are not packed in containers and are safely fastened inside the car to avoid shock and excessive vibrations. Computers could be positioned on the floor of the car,and monitors could be mounted on the seat with the screen down .

When transporting evidence—

  • Any electronic evidence should be kept away from magnetic sources.  Radiation transmitters, speaker magnets, and heated seats are a few examples of items that can contaminate electronic evidence.
  • Avoid leaving electronic evidence in your car for longer than necessary. Electronic devices can be harmed by extremes in temperature, humidity.
  • Maintain the integrity of the chain of custody while transporting any evidence.

Storing

  • Evidence should be kept safe and away from extremes in humidity and temperature. Keep it away from dust, moisture, magnetic devices, and other dangerous impurities.  Be advised that extended storage may cause important evidence—like dates, times, and system configurations—to disappear. Because batteries have a finite lifespan, data loss may occur if they malfunction. Whenever the battery operated device needs immediate attention, it should be informed to the relevant authority (eg., the chief of laboratory, the forensic examiner, and the custodian of the evidence). 

CONCLUSION:

Thus, securing the crime scene to packaging, transportation and storage of data are the important steps in the process of collecting digital evidence in forensic investigations. Keeping the authenticity during the process along with their provenance is critical during this phase. It is also important to ensure the admissibility of evidence in legal proceedings. This systematic approach is essential for effectively investigating and prosecuting digital crimes.

PUBLISHED ON
May 10, 2024
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