Forensic smartphone analysis using adhesives:Transplantation of Package on Package components

International audienceInvestigators routinely recover data from mobile devices. In many cases the target device is severely damaged. Events such as airplane crashes, accidents, terrorism or long submersion may bend or crack the device's main board and hence prevent using standard forensic tools. This paper shows how to salvage forensic information when NAND memory, SoC or cryptographic chips are still intact. We do not make any assumptions on the state of the other components. In usual forensic investigations, damaged phone components are analysed using a process called “forensic transplantation”. This procedure consists of unsoldering (or lapping) chips, re-soldering them on a functionnal donor board and rebooting.Package on Package (PoP) component packaging is a new technique allowing manufacturers to stack two silicon chips, e.g. memory, CPU or cryptographic processors. Currently, PoP is widely used by most device manufacturers and in particular by leading brands such as Apple, BlackBerry, Samsung, HTC and Huawei. Unfortunately, forensic transplantation destroys PoP components.This work overcomes this difficulty by introducing a new chip-off analysis method based on High Temperature Thixotropic Thermal Conductive Adhesive (HTTTCA) for gluing the PoP packages to prevent misalignment during the transplantation process. The HTTTCA process allows the investigator to safely unsolder PoP components, which is a crucial step for transplantation. To demonstrate feasibility, we describe in detail an experimental forensic transplantation of a secure mobile phone PoP CPU

Removing epoxy underfill between neighbouring components using acid for component chip-off

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Physical Fault Injection and Side-Channel Attacks on Mobile Devices:A Comprehensive Analysis

Today's mobile devices contain densely packaged system-on-chips (SoCs) with multi-core, high-frequency CPUs and complex pipelines. In parallel, sophisticated SoC-assisted security mechanisms have become commonplace for protecting device data, such as trusted execution environments, full-disk and file-based encryption. Both advancements have dramatically complicated the use of conventional physical attacks, requiring the development of specialised attacks. In this survey, we consolidate recent developments in physical fault injections and side-channel attacks on modern mobile devices. In total, we comprehensively survey over 50 fault injection and side-channel attack papers published between 2009-2021. We evaluate the prevailing methods, compare existing attacks using a common set of criteria, identify several challenges and shortcomings, and suggest future directions of research

Electrically conductive adhesives, thermally conductive adhesives and UV adhesives in data extraction forensics

International audienceRecent publications underline the interest of using polymers in microelectronics (Li and Wong, 2006a; Cui et al., 2014). Polymers are the ideal interconnect alternative to solder materials containing lead. Electrically Conductive Adhesives [ECAs] (Li and Wong, 2006b), Thermally Conductive Adhesives (TCAs) (Felba et al., 2011) and UV Adhesives (UVAs) (Asif et al., 2005) mainly consist of a polymeric resin (epoxy, silicon, polyurethane or polyimide) that provides physical and mechanical properties such as adhesion, mechanical strength while containing metal fillers (silver, gold, nickel or copper) that conduct electricity (Luo et al., 2016). Currently it is possible to find really cheap polymeric resin. Using these resins for digital forensic purposes is the focus of this paper, that we demonstrate in a hardware reverse engineering prototype case study.When considering new mobile devices, such as secure phones, it is often necessary to spy communication and perform numerous tests on the memory (e.g. by changing some bytes) to understand or modify the implemented security mechanisms (manipulate system time, locate password hashes, observe artefacts of implemented security algorithms, etc.). Traditional techniques use either laser attacks/probing (chip on) or soldering/read/re-soldering (chip off/on) (Heckmann et al., 2016, Jongh, 2014). These two techniques are unsuitable for repeated operations requiring many readings/changes/injections. This paper describes a concrete case study using adhesive properties complementary to chip on and chip off methods.We present the steps using different properties of adhesives (ECA, TCA, UVA) that we will lead to the realisation of a prototype particularly suitable for the repeating of the read phases/changes/injections necessary for reverse engineering secure mobile devices

P0131 - Electrically conductive adhesives, thermally conductive adhesives and UV adhesives in data extraction forensics

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Microfluidics and Nanofluidics Handbook

The Microfluidics and Nanofluidics Handbook: Two-Volume Set comprehensively captures the cross-disciplinary breadth of the fields of micro- and nanofluidics, which encompass the biological sciences, chemistry, physics and engineering applications. To fill the knowledge gap between engineering and the basic sciences, the editors pulled together key individuals, well known in their respective areas, to author chapters that help graduate students, scientists, and practicing engineers understand the overall area of microfluidics and nanofluidics. Topics covered include Finite Volume Method for Numerical Simulation Lattice Boltzmann Method and Its Applications in Microfluidics Microparticle and Nanoparticle Manipulation Methane Solubility Enhancement in Water Confined to Nanoscale Pores Volume Two: Fabrication, Implementation, and Applications focuses on topics related to experimental and numerical methods. It also covers fabrication and applications in a variety of areas, from aerospace to biological systems. Reflecting the inherent nature of microfluidics and nanofluidics, the book includes as much interdisciplinary knowledge as possible. It provides the fundamental science background for newcomers and advanced techniques and concepts for experienced researchers and professionals

Micro- and Nano Engineering for Polymerase Chain Reaction

In the frame of this thesis, polymerase chain reaction (PCR) is analyzed from analogue to digital, from thermal cycling to a single temperature. An "analogue" measurement infers certain measurements based on the measured pattern, whereas a "digital" measurement method measures a variable quantitatively and discretely. First, an open system with a thermal gradient feature to optimize PCR is described. The gradient is measured through encapsulated aqueous beads of a temperaturedependent dye with volumes in the low microlitre range within slightly larger oil droplets, forming virtual reaction chambers (VRCs). VRCs exploit the advantages of microfluidics and droplets in a simple way while circumventing many practical problems. As the gradient feature allows for testing a range of annealing temperatures simultaneously, the optimal annealing temperature can be determined easily in a single run. Second, a microfluidics platform using capillaries was built to generate nanoscale droplets. Those monodisperse, isolated compartments are used as nano-reactors for isothermal PCR – recombinase polymerase amplification (RPA). By precise definition of the starting time of RPA, the method detects nucleic acid at the single molecule level by counting the presence or absence of the amplification of individual molecules confined to isolated compartments. Third, a biomimetic chip with a nanowell structure was duplex-imprinted from a natural insect, Cicada, to run digital PCR. The glassy wings of Cicada, which are abundant in nature, exhibit a strikingly highly organized nanopillar structure over its membrane on both sides. A duplex nanoimprint technique was proposed to fabricate the chip out of the cleanroom, which combines the top-down and bottomup nanofabrication technique to speed up the fabrication process and achieve higher throughput. Further experiments for digital PCR using the Cicada chip are II still ongoing. Additionally the Cicada nanowell chips has a potential to be employed in other applications, such as nanoparticles self-assembly, Matrix assisted laser desorption ionization (MALDI) etc.Im Rahmen dieser Arbeit wurde die Polymerase-Kettenreaktion (Polymerase chain reaction; PCR) untersucht, von Analog bis Digital als auch bei zyklisch wechselnden Temperaturen und festen Temperaturwerten. Eine „digitale“ Messung misst hierbei quantitativ und eigenständig eine bestimmte Variable, wohingegen „analoge“ Messungen bestimmte Messwerte extrapolieren, basierend auf einem gemessenen Muster. Zuerst wird ein offenes System mit einem Temperatur-Gradienten zur Optimierung der PCR beschrieben. Der Gradient wurde vermessen mittels verkapselter, wässriger Mikrobeads mit einem temperaturabhängigen Farbstoff mit Volumina im niedrigen Mikroliter-Bereich innerhalb leicht größerer Öltropfen, die hierbei eine Virtuelle Reaktionskammer (VRC) bilden. VRCs stellen einen simplen Weg zur Untersuchung der Vorteile der Mikrofluidik und Droplettechnologie dar, wobei viele praktische Probleme verhindert werden können. Durch die Eigenschaften des Gradienten war es möglich, eine große Breite von Temperaturen zu testen, um die optimale Annealing-Temperatur in einem einzelnen Experiment zu ermitteln. Zweitens wurde eine mikrofluidische Plattform hergestellt, um Tropfen in Nano- Größe zu generieren. Diese monodispersen, isolierten Kompartimente wurden als Nanoreaktoren für isothermale PCR-Rekombinase Polymerase Ampifikation (RPA) verwendet. Durch genaue Definition der Startzeit der RPA konnte die Methode verwendet werden, um Einzelmoleküle von Nucleinsäuren nachzuweisen über Präsents oder Absenz einer Amplifikation des jeweiligen Moleküls in den isolierten Kompartimenten. Drittens wurde ein bio-mimetischer Chip mit Nanowell-Strukturen für PCR als Duplex-Abdruck eines Insektes, Cicada, geformt. Die Glasflügel von Cicada, welche in großer Fülle in der Natur vorliegen, besitzen eine hoch-organisierte NanopillarIV Struktur, verteilt über die Membranen auf beiden Seiten. Eine Duplex- Nanoabdruck Technik wurde verwendet, um die Chips außerhalb eines Reinraums herstellen zu können, was sowohl die Top-Down- als auch die Bottom-Up- Nanoherstellungstechniken kombiniert, um somit den Fabrikationsprozess beschleunigen und einen höheren Durchsatz generieren zu können. Weitere Experimente mit dem Digital-PCD Cicada Chip sind in Vorbereitung. Des Weiteren hat der Cicada Nanowell-Chip großes Potential in unterschiedlichen Anwendungen weiter genutzt zu werden, wie beispielsweise selbstorganisierende Nanopartikel, Matrix-assisted laser desorption ionization MALDI etc.本论文从模拟到数字，从热循环到单一温度对聚合酶链式反应(PCR) 进行了分析。“数字”测量方法定量且离散地测量某个变量，而“模 拟”测量则是基于测量的模式推断某些测量结果。 首先，本文描述了一个开放的，用于优化PCR 的温度梯度系统。温度 梯度通过温度依赖性荧光染料的胶囊化水珠测量。水珠的体积在低微 升范围内，外面被体积稍大的油滴包裹起来，形成虚拟反应室(VRC)。 由于梯度特征允许同时测试一系列退火温度，所以可以在单个实验中 很容易地确定最佳退火温度，从而达到优化PCR 的目的。 其次，本文介绍了一个基于毛细管的微流体平台，用来产生纳米级的 液滴用于运行数字液滴PCR。这些单分散的液滴隔离室被用作等温 PCR – 重组酶聚合酶扩增 (RPA) 的纳米反应容器。通过精确定义RPA 的起始时间，该方法计数被限制在隔离液滴中的单个分子的扩增结果 的存在与否达到检测单分子水平核酸的目的。 最后，本文介绍了具有纳米孔结构的仿生芯片，用以运行数字PCR。 该创意是从天然昆虫 - 蝉(Cicada)得到灵感。蝉在自然界储藏丰富， 它的透明翅膀在膜的正反面上呈现出惊人的高度有序的纳米柱状结构。 本文的第六章提出了一种双面纳米压印技术，无需无尘室制造芯片， 将自上而下和自下而上的纳米加工技术结合起来，以加快制造过程并 实现更高的生产量。由于检测仪器的限制，使用Cicada 芯片的数字 PCR 实验仍在进行中。此外，蝉纳米芯片将用于其他应用，如纳米粒 子自组装，基质辅助激光解吸电离(MALDI)等

Exploitation and exploration of PCR in microfluidic systems with gradient temperature environments

The main goal of the work was to establish a wholesome picture off all relevant processes for a sample-in, answer out genetic system and to integrate the whole process on a one step device from sample collection to final result. The genetic analysis process consists of ideally three steps: sample preparation, chemical reaction, and analysis. Each of the steps is different and requires a specific environment, where sample preparation might use additives, they might later interfere with the reaction itself or lead to misleading results in the analysis phase. It was found to be quite a challenging process to synchronize the three without compromising each other efficiency. The design of the devices was a gradual process with an iterative approach. The initial trials were focused on enabling on-chip PCR with spatial melting analysis. In the later work, sample preparation was embedded into the process, though at the cost of reaching the used fabrication method limitations. Apart from the challenges of integrating the process into one complete entity, the gradual enhancement of the system in respect to size and performance consistency was pursued. A range of applications and variations to the devices were fabricated each representing a unique solution to many modern-day problems

Aqueous solvent-gel cleaning of poly (methyl methacrylate) surfaces in museum collections

This research explores the use of aqueous solvent-gel systems for cleaning transparent and highly polished poly(methyl methacrylate) (PMMA) surfaces found in historical, technological, art and design museum collections. Surface transparency and glossiness were identified as conservators’ priorities when cleaning plastics, in a survey conducted for the purposes of this research. The absence of established conservation cleaning treatments for plastics has led to the inappropriate use of methods employed on other materials. Gels are used here as solvent carriers for their potential to optimise cleaning with their purported abilities to control solvent diffusion and limit mechanical stresses. Factors affecting cleaning are investigated through a series of statistically designed laboratory-based experiments on unaged and accelerated light-aged PMMA samples. A range of polar and nonpolar solvents, and natural as well as synthetic polymeric matrices are tested independently and in combination. Artificial oily dirt and pressure-sensitive adhesive are applied to surfaces to respectively simulate human fingerprints and labels/packaging tape remains. PMMA is mechanically and chemically characterised with Dynamic Mechanical Analysis, tensile testing and pyrolysis-Gas Chromatography/Mass Spectrometry. Macroscopic observation, stereomicroscopy and Scanning Electron Microscopy imaging are used to evaluate visual change. Weight and gloss measurements offer quantitative evidence of post-treatment changes. Surface chemical modifications are detected with Attenuated Total Reflection Fourier Transform Infrared spectroscopy and bulk mechanical changes are monitored with Nuclear Magnetic Resonance Mobile Universal Surface Explorer. Finally, three PMMA museum objects with a user life are treated with the successful gels to test the validity of lab-based results. The research has shown that direct application of deionised water, ethanol, isopropanol and petroleum ether with cotton swabs causes dissolution of PMMA components and is to be avoided. Solvents dispersed in Agar, Gellan, Pemulen TR2/triethanolamine and 80 % Poly(vinyl acetate)/borax gels regulate the damaging solvent effect and reduce visual damage. Carbopol EZ2/Ethomeen C-25 is unsuitable due to inducing numerous scratches and leaving gel residues. Pemulen performed the best; with isopropanol being the most efficient at oily dirt removal and petroleum ether at adhesive removal. Repeated gel applications are recommended for improved results. This research recommends the use of Poly(vinyl acetate)/borax ethanol and Pemulen TR2/triethanolamine gels/emulsions with isopropanol or petroleum ether for cleaning transparent and glossy PMMA in museum collections