Navigating the Complexities of Mobile Forensics: Understanding the Process in Depth

By Jeffrey Gaor | 27 November 2023

Introduction:

The widespread use of mobile devices poses numerous challenges for digital forensics professionals. As individuals increasingly rely on smartphones for communication, work, and personal activities, the importance of effective mobile forensics becomes evident. This article explores the multifaceted challenges faced by forensic examiners in this domain and offers insights into potential solutions. In the current era dominated by mobile phones, their significance in both lawful and unlawful activities has dramatically increased. This piece delves into the obstacles, tools, and considerations within mobile phone forensics, highlighting the continuous evolution of mobile phone technologies.

Process of Digital Evidence Analysis:

It is crucial to distinguish digital forensics from mobile phone forensics. While digital forensics covers a broad spectrum of hardware and software, mobile device forensics grapples with a multitude of hardware and software standards, making the creation of a universally accepted standard instrument nearly impossible.

Figure1: Illustration of the various steps in the digital forensic life cycle.

While both Computer Forensics and Mobile Phone Forensics aim for precise data collection and analysis, they encounter distinct challenges. Mobile forensics deals with frequent operating system upgrades, necessitating vigilant monitoring for updates. The perpetual connectivity of mobile devices underscores the need for meticulous evidence processing to prevent data contamination, especially when remotely instructed to erase stored data.

The Mobile Forensics Process: Steps and Types

The term "mobile devices" encompasses a wide array of gadgets, from mobile phones and smartphones to tablets, wearables, and GPS units. These devices play a crucial role in our lives and store vast amounts of user information. In the context of digital forensics, the importance of mobile devices cannot be overstated. The prevalence of mobile technology has given rise to significant trends such as the Internet of Things, Cloud Computing, and Big Data.

Information stored on mobile devices may include:

•   Call history (incoming, outgoing, missed)
•   Phonebook or contact lists
•   SMS text, application-based, and multimedia messaging content
•   Multimedia files (pictures, videos, audio)
•   Internet browsing history
•   To-do lists, notes, calendar entries
•   User credentials (passwords, passcodes, swipe codes)
•   Geolocation data and Wi-Fi connection information
•   Data from various installed apps
•   System files, usage logs, error messages
•   Deleted data from all of the above

Understanding the Mobile Forensics Process:

Many individuals underestimate the intricacies of mobile forensics, particularly as mobile devices play a pivotal role in the convergence of professional and personal activities. To put this complexity into perspective, consider that the storage capacity of today's smartphones -typically 64 gigabytes - equals a staggering 33,500 reams of paper when printed. The mobile forensics process aims to recover digital evidence from mobile devices while ensuring the preservation of this evidence in a forensically sound condition.

The mobile forensics process mirrors procedures in other branches of digital forensics but possesses unique elements that demand adherence to specific methodologies and guidelines. Following the correct approach is crucial for the examination of mobile devices to yield accurate and reliable results. Forensic Examiners, Incident Responders, and Corporate Investigators are key figures entrusted with the responsibility of executing the mobile forensics process. In inquiries related to crimes involving mobile technology, these individuals play a critical role in acquiring essential information, such as device passwords, pattern locks, or PIN codes.

Navigating the Key Steps in the Mobile Forensics Process

1. Collection and Preservation

Digital forensics operates on the principle that evidence must be adequately preserved, processed, and made admissible in a court of law. Legal considerations come into play during the seizure of mobile devices, with risks including lock activation and network/cellular connections. To mitigate these risks, network isolation is advised, achievable through methods like activating Airplane Mode, disabling Wi-Fi and Hotspots or cloning the device SIM card.

Equipment such as Faraday bags and external power supplies are commonly included in the mobile forensics toolkit, ensuring the isolation of devices during transportation to the laboratory. Investigators must also exercise caution regarding mobile devices potentially connected to unknown incendiary devices or other traps set to cause harm at the crime scene.

2. Acquisition and Extraction

The objective of this phase is to retrieve data from the mobile device, a task that involves unlocking a locked screen using the correct PIN, password, pattern, or biometrics. It is noteworthy that, despite the convenience of biometric approaches, their reliability may not be guaranteed in certain legal contexts. Managing data on mobile devices poses challenges due to their inherent mobility.

Data synchronisation, whether conducted directly or via the cloud, introduces complexity to the acquisition process. Investigators must remain vigilant for signs that data may extend beyond the mobile device as a physical object, influencing the collection and preservation process. The identification of data sources precedes proper information collection, presenting unique challenges in the realm of mobile technology. Various protocols for data collection may be necessary based on design specifications. Forensic examiners can utilise SIM Card imaging, creating a replica image of the SIM Card content while preserving the original evidence, ensuring data accuracy and integrity.

3. Examination and Analysis

The forensic expert initiates every digital investigation involving mobile devices by identifying crucial details, including the type of mobile device(s), network type, carrier, and service provider. Numerous forensic tools may be employed for data acquisition and analysis, with popular choices including AccessData, Sleuthkit, and EnCase.

Timeline and link analysis available in these tools help correlate significant events together from a forensic analyst's perspective. Information, evidence, and findings extracted must be presented clearly, concisely, and comprehensively to other forensic examiners or a court.

3.1 Non-Invasive vs. Invasive Forensics

Irrespective of the chosen mobile forensic method, it is imperative to create a well-defined policy or plan for execution and to meticulously adhere to its steps to avoid grave consequences.

Commencing with non-invasive forensic techniques is recommended due to their lower impact on a device's integrity. Built-in security features must be approached with caution, considering potential risks such as data loss through improper procedures.

3.2 Non-Invasive Methods

Non-invasive methods encompass tasks such as unlocking SIM and operator locks, conducting operating system updates, and modifying International Mobile Equipment Identity (IMEI) number. These techniques may be unsuitable for severely physically damaged devices. Examples of non-invasive mobile forensic methods include manual extraction, logical extraction, Joint Test Action Group (JTAG) method, and Hex dump.

3.3 Invasive Methods

Invasive methods, typically longer and more complex, may be necessary for entirely non-functional or severely damaged devices. The chip-off method involves obtaining data directly from the mobile device's memory chip. This technically challenging process requires specific hardware and expertise to prevent data loss.

The micro read method, reserved for serious national security crises, involves a meticulous analysis of physical gates on the memory chip using an electron microscope. This highly specialised and resource-intensive approach is used sparingly due to its complexity and cost.

Challenges in Mobile Forensics

Investigators must adhere to particular guidelines to ensure the acceptance of evidence in a court of law. The following outlines the steps involved in the process of mobile forensics:

1. Data Accessibility Across Devices

The ability of data to be accessed, stored, and synchronised across multiple devices poses a significant challenge. The volatile nature of this data, coupled with the risk of remote manipulation or deletion, necessitates heightened efforts for its preservation.

2. Hardware Differences

The multitude of mobile phone models from various manufacturers presents a significant challenge for forensic examiners. Differences in size, hardware, features, and operating systems demand constant adaptation to new challenges and staying updated on mobile device forensic techniques.

3. Mobile Operating Systems

Unlike the dominance of Windows in personal computers, mobile devices utilise a variety of operating systems, each with multiple versions. This diversity adds a layer of complexity for forensic investigators seeking to extract digital evidence.

4. Mobile Platform Security Features

Modern mobile platforms come equipped with robust security features, including encryption mechanisms from hardware to software layers. Breaking through these security measures becomes a hurdle for forensic examiners during data extraction.

5. Lack of Resources

The growing number of mobile devices requires an expanding toolkit for forensic examiners. USB cables, batteries, and chargers for various devices must be maintained to facilitate the acquisition of diverse mobile phones.

6. Preventing Data Modification

Preserving the integrity of data during forensic examinations is a fundamental rule, yet it proves challenging with mobile devices. Background processes running even in apparent "off" states can lead to unintended data modifications.

7. Anti-Forensic Techniques

Techniques like data hiding, obfuscation, forgery, and secure wiping make digital media investigations more intricate, requiring forensic examiners to navigate through deceptive practices.

8. Dynamic Nature of Evidence

Digital evidence can be easily altered, intentionally or unintentionally. Actions as simple as browsing an application on a phone can result in modifications to the stored data.

9. Accidental Reset

Mobile phones offer features to reset everything, and accidental resets during examinations can lead to irreversible data loss.

10. Passcode Recovery

Accessing a device protected by a passcode without damaging data presents a challenge, as bypass techniques may not work universally across all versions.

11. Communication Shielding

Mobile devices communicate through various networks, and the potential for communication altering device data requires careful consideration after seizing a device.

12. Lack of Tool Availability

The diverse range of mobile devices necessitates a combination of tools, as a single tool may not support all devices or functions. Selecting the right tool for a specific phone adds an additional layer of complexity.

13. Malicious Programs

The presence of malware or other malicious software on a device introduces the risk of spreading to other devices, requiring careful handling during forensic examinations.

14. Legal Issues

Mobile devices often play a role in crimes that transcend geographical boundaries, requiring forensic examiners to navigate complex multijurisdictional legal issues.

Conclusion

The realm of mobile forensics presents an intricate and continually evolving landscape, demanding that forensic professionals possess both comprehensive understanding and adaptability. The escalating ubiquity of mobile devices, combined with ongoing technological progress, emphasises the critical nature of a thorough comprehension of the mobile forensics process. Challenges such as diverse hardware, operating systems, security features, and anti-forensic techniques necessitate a nuanced and well-defined approach, highlighting the differentiation between non-invasive and invasive methods. Forensic examiners and investigators, guiding the mobile forensics journey from seizure to extraction, play a pivotal role in ensuring the accurate preservation of digital evidence.

The identified challenges, encompassing issues like data accessibility, legal complexities, and the dynamic nature of evidence, underscore the ongoing requirement for education and adaptation within the field. Collaboration among forensic experts, technology developers, and legal entities is crucial for establishing universal standards and protocols, thereby enhancing the reliability of digital evidence. In the pursuit of justice, the mobile forensics community must remain resilient, innovative, and committed to adapting methodologies in harmony with rapid technological advancements, ensuring the integrity of digital evidence.