Apple introduced the smartphone in June 2007. Since then, the mobile market has been dominated by this type of gadget. Smartphones have become the archives of our personal and professional lives as they have spread over the world. These gadgets contain the following:
- Our pictures
- Our text messages
- Our email messages
- Our search and Internet browsing history
- Our specialized applications
- Our location data tracking every move we make
The mobile device can give the forensic investigator a detailed image of the suspect's actions and thoughts, as this list suggests. Because of this, mobile device forensics might be the most crucial component of a forensic investigation. In the forensics sector, mobile forensic investigators are in great demand since almost all investigations include mobile devices, and many older, more experienced investigators lack the skills and resources necessary to carry out a successful mobile device investigation.
We will start with some basic ideas in this blog article and work our way up to more sophisticated extraction methods for encrypted devices.
Basics of Mobile Forensics
The principles of mobile device forensics include:
- the methodologies
- the processes and
- the best practices
utilized to get, store, examine, and document digital evidence from portable electronics like tablets and smartphones. For the study and report to be accepted in legal arenas like criminal proceedings, best practices are essential.
The integrity and admissibility of evidence in civil, criminal, and corporate investigations depend on these principles.
Scope of Mobile Forensics
In order to maintain the credibility and admissibility of evidence in court, mobile device forensics is a subfield of digital forensics that focuses on the forensically sound extraction and analysis of data from mobile devices. Smartphones, tablets, and other portable digital devices—which frequently hold location information, conversation logs, application files, and more—are among the devices that are analyzed.
The Mobile Forensics Process
Usually, the procedure consists of these four main steps:
1. Seizure (Preparation & Collection):
- Make sure the gadget is secure and record the chain of custody.
- Maintain the device's status (e.g., keep it turned on if you can, isolate it from networks using Faraday bags to stop remote wipes).
- Take pictures and make notes on the physical state, lock status, and device identifiers (IMEI, SIM info).
2. Acquisition:
- Using specified tool, create a forensic image of the device's data.
- To confirm the integrity of the obtained picture, use hashing.
- Depending on the kind of device and the circumstances, select the acquisition technique (logical, physical, or file system).
3. Analysis:
- Look for proof in the retrieved data, such as deleted files, SMS, call logs, app data, contacts, photographs, and GPS records.
- Utilize forensic tools to analyze logs, proprietary file formats, and databases (such SQLite), frequently handling data fragmentation and encryption.
- Reconstruct timelines and user behavior by correlating data from several sources.
4. Reporting:
- Make sure all procedures are repeatable and transparent for legal examination; document findings in a clear, organized report appropriate for both technical and non-technical audiences.
Types of Evidence Recovered
- Communication logs, including SMS, MMS, phone logs, and chat app data (such as WhatsApp and Signal).
- Metadata includes geographical information, sender/receiver details, and timestamps.
- Files: Documents, music, video, photos, logs, and application files
- SIM data: Network details, contacts, and subscriber identification
- Deleted data: Recoverable pieces from app caches or unallocated space
Currently Used Data Extraction Techniques from Encrypted Mobile Devices
This section introduces the main forensic data extraction methods now in use for contemporary mobile devices as well as the shortcomings of device security measures. Although there are certain real-world outliers where additional data extraction techniques are available, such as when the target device is already "rooted" or "jailbroken," those situations are not covered here.
- File system extraction
- Cloud data acquisition
- Manual/logical extraction
- Physical data extraction
- Bypassing Device lock/extracting lock-related Information
- Data acquisition with custom boot loaders
Emerging Techniques in Data Extraction Techniques For Encrypted Devices
The following approaches have been investigated as potential ways for forensic data extraction from contemporary mobile devices, in addition to the forensic data collecting techniques discussed in the preceding section.
Side-channel analysis
Current flow or electromagnetic (EM) emissions are two ways that information about integrated circuits (ICs) operating on a circuit board might escape. Internal secrets like cryptographic keys can occasionally be extracted using this knowledge. For smart cards and other security devices, this kind of study is known as side-channel analysis (SCA), a well-liked area of security research. Recent research has demonstrated that SCA may be used to extract a cryptographic key from a contemporary mobile device's application processor.
SCA is a potential method for obtaining cryptographic keys from contemporary mobile devices, but since each application processor is different, study is necessary. Bootloaders may be decrypted with the key after it has been obtained. To reduce SCA vulnerabilities, device makers are also reducing the size of their technologies and including features like voltage frequency optimization and heterogeneous operation.
Fault injection
Fault injection is a method that involves manipulating the controller device's inputs to cause the target system to behave illegally. Injecting optical beams, transmitting electromagnetic signals, and glitching or underfeeding the power supply are a few examples of fault injection techniques. Studies have previously been conducted to demonstrate the effectiveness of fault injection in targeting the boot stage and removing the most privileged code from an Android device. Disabling the lock of debugging interfaces like JTAG on the target device may also be accomplished by fault injection.
SoC Reverse Engineering
System on a Chip (SoC) die-level reverse engineering uses extremely sophisticated lab equipment to physically access the internal circuitry of SoCs on mobile devices. By examining internal circuit connections, SoC dielevel reverse engineering can reveal the topology of the system. A semiconductor die is made up of many linked layers. One can extract the overall architecture and attempt to study and comprehend how the target system functions by delayering each layer and converting the link into a circuit. SoC reverse-engineering has been done for a variety of purposes, including as piracy or counterfeiting. The retrieval of hardware-bound essential information, which is kept in a SoC's one-time programmable memory section, is a major driving force behind SoC dielevel reverse engineering for forensic applications.
New Mobile Forensic Model
As we've seen above, the methods used now to access user data on contemporary mobile devices differ significantly from those used in the past. Forensic data extraction methods have traditionally concentrated on obtaining physical data, which may then be processed to recover erased data. Because the data was kept in readable text on mobile devices' non-volatile memory, this method was previously successful. Consequently, the five-level data extraction approach has been adopted as a standard model.
However, merely obtaining raw data is no longer helpful in recovering user data due to the installation of encryption and other intricate security mechanisms. Even worse, harmful processes like chip-off might ruin essential elements required to decipher obtained data. Furthermore, data leftovers on the system may be efficiently erased by mobile devices' safe deletion functions, and it is becoming nearly difficult to recover deleted data from physical data. Furthermore, regardless of the acquisition level, obtaining user data—logical or physical—without user authentication credentials is becoming extremely difficult.
As a result, classifying the mobile data extraction technique according to the kind of extracted data is losing its effectiveness. The primary goal of forensic data extraction is now either retrieving the encryption key or the data in clear-text. This can only be accomplished by either finding and gaining access to the stored cryptographic keys or by taking advantage of system flaws on the target device in the absence of proper user authentication. However, before working on the target mobile device, both approaches need a significant amount of reverse-engineering. We suggest the following new mobile forensic data extraction model in light of the existing circumstances:
User secret based acquisition
The target smartphone may be physically handled and configured to allow data extraction through its user interfaces if an examiner can unlock the phone with the proper user credentials. Forcing the device owner to provide the password is not thought to be a suitable approach. However, acquisition could be possible via obtaining the device owner's biometric data. Once the device has been unlocked, an examiner can change its settings and root it to retrieve logical, file system, or physical data.
Reverse-engineering based acquisition
In forensic research, reverse-engineering contemporary mobile devices is crucial. Hardware and software may both be reverse-engineered. An examiner may be able to reconstitute the original user data once they have learned the internal workings of the target mobile device by reverse-engineering. Finding the encryption method and retrieving the encryption key are two examples. After obtaining such details, an examiner can use the proper techniques to obtain the physical data from the target smartphone and decrypt it off-device.
Vulnerability exploitation based acquisition
For data extraction, these features must be either deactivated or circumvented when the target device is encrypted and locked. It is typically necessary to take advantage of system flaws in order to get around or disable encryption, device locks, and other security mechanisms. It could be necessary to combine software and hardware attacks in order to exploit the vulnerability. Examiners have the option to get either whole or partial logical, file system, or physical data after circumventing such features. The use of open and unpatched vulnerabilities is justified from a legal standpoint, as covered in section 5. However, successful data extraction frequently requires zero-day vulnerabilities discovered through thorough reverse-engineering. The efficacy of vulnerability exploitation in the field of digital forensics has already been demonstrated by several studies.
Conclusion
Mobile forensics has evolved into one of the most critical branches of digital investigation, driven by the ever-increasing dependence on smartphones for personal, professional, and social activities. As modern devices integrate advanced encryption, secure hardware modules, and sophisticated deletion mechanisms, traditional forensic techniques are no longer sufficient. Investigators now face the dual challenge of preserving evidentiary integrity while overcoming complex security barriers.
Emerging techniques such as side-channel analysis, fault injection, and SoC reverse engineering highlight a shift from simple data extraction to deep technical exploitation and system-level understanding. At the same time, the proposed new forensic model—focused on user-secret acquisition, reverse-engineering-based acquisition, and vulnerability-exploitation-based acquisition—reflects the realities of today’s encrypted ecosystem.
Ultimately, the future of mobile forensics lies in continuous research, ethical vulnerability exploitation, and the development of advanced tools that keep pace with rapidly evolving device security. As smartphones continue to serve as comprehensive repositories of user activity, mastering these modern extraction techniques will be essential for investigators seeking accurate, admissible, and reliable digital evidence.