Digital forensics is the process of collecting, analyzing, and preserving digital evidence found on electronic devices such as computers, smartphones, and other digital storage media. The goal of digital forensics is to extract data and information that can serve as admissible evidence in a court of law or legal proceedings.
What is the purpose of digital forensics?
The main purposes of digital forensics include:
- Gathering evidence from digital devices and storage media that can be presented in a court of law or legal proceedings
- Reconstructing timelines and events leading up to cybercrimes or information security incidents
- Identifying the perpetrators of cybercrimes and attributing their actions
- Recovering deleted, hidden, encrypted or corrupted files and data
- Supporting the claims and arguments of parties in legal disputes involving digital evidence
- Investigating IP theft, corporate espionage and misconduct within organizations
Overall, the goal is to leverage specialized forensic tools and techniques to find digital artifacts and uncover the truth about cyber incidents.
What are the principles of digital forensics?
Digital forensics investigations are guided by fundamental principles such as:
- Minimal handling of evidence – Original evidence should be accessed and handled as little as possible to avoid tampering or alterations.
- Accounting for any change – Any access, duplication or processing of digital evidence must be properly documented.
- Comply with chain of custody – There should be a verifiable trail documenting the collection, custody, control and transfer of evidence.
- Apply validated tools and techniques – Forensic tools and examination techniques should be scientifically validated, tested and peer-reviewed.
- Ensure compatibility – Forensic tools should be compatible with the evidence being examined to avoid alterations.
- Independence from external influences – Examinations should be impartial and unaffected by external or personal influences.
What are the different types of digital forensics?
Digital forensics can be categorized into different sub-disciplines based on the type of evidence handled:
- Computer forensics – Recovery of data and forensic examination of computers, laptops and other digital devices.
- Network forensics – Monitoring, capturing and analyzing incoming and outgoing network traffic for investigation purposes.
- Mobile device forensics – Extraction and analysis of data from mobile devices such as smartphones, tablets and GPS devices.
- Database forensics – Retrieval and presentation of digital information from database management systems used in corporate and government environments.
- Cloud forensics – Collection and analysis of forensic data in public or private cloud computing environments.
- Digital video forensics – Analysis and authentication of digital video files and streams using scientific techniques.
What are the steps involved in a digital forensics investigation?
A typical digital forensics investigation involves several stages:
- Planning – Define the scope and objectives of the investigation based on the specifics of the case.
- Evidence collection – Identify, label, record and acquire digital evidence from all potential sources while maintaining integrity.
- Examination and analysis – Extract and analyze data using appropriate tools while following chain of custody requirements.
- Documentation and reporting – Document the procedures used along with the observations and results from the examination.
- Data presentation – Prepare collected digital evidence and results to share with internal stakeholders or for legal proceedings.
What are some examples of digital evidence?
Common examples of digital evidence that investigators look for include:
- Files such as documents, photos, audio and video files
- Emails and instant messaging chats and attachments
- System and application logs
- Internet browsing history and bookmarks
- Network packet captures
- Operating system and application metadata
- Hidden, encrypted and deleted files
Essentially any data stored or transmitted digitally can serve as useful evidence. The more data collected and examined, the more complete the reconstructed picture of events.
What are some key forensic artifact locations on Windows and Apple devices?
Some key places that investigators look for forensic artifacts on Windows systems include:
- Registry hives such as SYSTEM, SAM, SECURITY and SOFTWARE
- Swap files, memory dumps and cached files
- Windows event logs
- Recycle Bin and hidden partitions
- Shortcut (LNK) files
- Prefetch files and jump lists
- Shadow copy backups
On Apple devices, some important forensic artifact locations are:
- Plists containing app data, bookmarks and iOS settings
- SQLite databases storing app data and iOS metadata
- Log files recording device events and network activity
- PurpleRestore files showing iTunes backup history
- Keyboard caches with timestamps
- Mobile Safari and Chrome browser histories
What tools are used for digital forensics?
Some common digital forensic tools include:
- EnCase – Comprehensive forensics platform for evidence acquisition, preservation, analysis and reporting.
- FTK – AccessData’s forensic toolkit for examination of computer and mobile evidence.
- X-Ways Forensics – Integrated computer forensics tool for data recovery and analysis.
- ProDiscover Forensic – Computer forensics tool supporting law enforcement and organizations.
- Cellebrite UFED – Extracts and decodes data from seized mobile devices.
- Oxygen Forensic Detective – Mobile device examination suite for iOS, Android, Cloud services, and IoT devices.
- Volatility – Open-source memory forensics framework for analysis of memory dumps.
Investigators also employ other tools for network traffic capturing, password cracking, filesystem parsing and to reconstruct web activity and artifacts.
What are some common procedures and techniques in digital forensics?
Digital forensics experts use many techniques and procedures including:
- Disk imaging – Creating bit-for-bit forensic copies of hard drives or other digital storage media while preserving the original evidence.
- Data carving – Extracting files based on header and footer sequences without relying on the filesystem metadata.
- Deleted file recovery – Reconstructing deleted data residing in unallocated space on the disk.
- Decryption – Cracking or bypassing encryption used on files, hard drives and storage media.
- Timeline analysis – Creating a timeline of events from metadata like file timestamps and system logs.
- Data hashing – Generating cryptographic hashes for collected evidence data sets to validate their integrity.
- RAM analysis – Dumping and analyzing volatile data in the computer’s memory which is lost on shut down.
What are some characteristics of digital evidence?
Some key characteristics of digital evidence include:
- Easy to modify or destroy – Digital evidence can be easily edited, damaged, or deleted both intentionally and accidentally.
- Latency effect – Digital evidence tends to be temporary and can be lost through normal computer operations over time.
- Difficult to authenticate – Establishing a chain of custody and truly authenticating digital evidence presents challenges.
- Requires technical skills – Specialized tools and skills are required to acquire and interpret digital evidence appropriately.
- Coexistence of incriminating and exculpatory evidence – A device might contain evidence that both implicates and exonerates a subject under multiple charges.
- Possibly located across multiple devices or systems – Relevant evidence might be stored across several hard drives, devices or cloud-based systems.
What qualifications and certifications are available for digital forensics careers?
Some career qualifications and certifications in digital forensics include:
- Vendor neutral certifications such as GIAC Certified Forensic Analyst (GCFA) and GIAC Certified Forensic Examiner (GCFE) from the SANS institute.
- CompTIA Cybersecurity Analyst (CySA+) certification covering skills like threat management and vulnerability detection.
- Vendor specific certifications for popular tools such as EnCase Certified Examiner (EnCE), AccessData Certified Examiner (ACE), and Cellebrite Certified Logical Operator (CCLO).
- Certified Computer Examiner (CCE) from the International Society of Forensic Computer Examiners.
- Relevant computer and IT certifications like CompTIA A+, Network+, and Security+.
- Formal cybersecurity, information security, or digital forensics degree programs.
What are some examples of high profile digital forensic cases?
Some notable and public digital forensics cases include:
- The digital forensics investigation into Enron that uncovered extensive financial and accounting fraud.
- The use of forensic data extraction from automotive systems in the Toyota unintended acceleration investigation.
- Microsoft investigation of the 2001 “Code Red” worm that leveraged digital forensic techniques.
- FBI investigation of child pornography websites that employed extensive computer forensics.
- The crash of SilkAir Flight 185 where digital forensics found evidence of tampering with the flight data recorder.
- The Samantha Wright case where video forensics proved her death was not a suicide.
How are smartphones and IoT devices changing digital forensics?
The proliferation of smartphones and Internet of Things (IoT) devices is impacting digital forensics by:
- Introducing new sources of potential evidence via mobile apps, activity trackers, smart home tech etc.
- Increasing storage and encryption capabilities making evidence harder to access.
- Enabling faster evidence destruction with remote wipe capabilities.
- Increasing number of proprietary formats and platforms requiring more tools and skills.
- Generating vastly higher volumes of personal data belonging to victims and suspects.
- Requiring investigators to expand capabilities into mobile, IoT, cloud and big data realms.
What are some measures against digital evidence tampering?
Best practices to preserve integrity and prevent tampering of digital evidence include:
- Restricting access and handling only to authorized personnel.
- Following chain of custody procedures throughout the process.
- Using write-blocking tools and filesystem protection techniques.
- Cryptographically hashing evidence files to detect alterations.
- Storing evidence securely with limited physical and electronic access.
- Documenting all steps performed and any changes made during acquisition and handling.
- Using forensic disk images instead of original devices whenever possible.
Conclusion
In summary, digital forensics involves the collection, preservation, analysis and presentation of digital artifacts stored on electronic devices and systems. Leveraging specialized tools and techniques, investigators reconstruct cyber incidents while adhering to sound forensic principles. Digital evidence provides critical insights into cybercrimes, information security incidents and legal disputes. However, its delicate nature, complexity and proliferation across multiple devices and platforms poses challenges for evidence recovery and authentication. Understanding the fundamental concepts, procedures and legal considerations are important for utilizing digital forensics effectively in a wide range of situations and investigations.