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2007

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Articles 3391 - 3420 of 6758

Full-Text Articles in Physical Sciences and Mathematics

Rapid Volume Loss From Two East Greenland Outlet Glaciers Quantified Using Repeat Stereo Satellite Imagery, Leigh A. Stearns, Gordon S. Hamilton Mar 2007

Rapid Volume Loss From Two East Greenland Outlet Glaciers Quantified Using Repeat Stereo Satellite Imagery, Leigh A. Stearns, Gordon S. Hamilton

Earth Science Faculty Scholarship

The coastal portions of Kangerdlugssuaq and Helheim glaciers in southeast Greenland lost at least 51 +/- 8 km(-3) yr(-1) of ice between 2001-2006 due to thinning and retreat, according to an analysis of sequential digital elevation models (DEMs) derived from stereo ASTER satellite imagery. The dominant contribution to this ice loss was dynamic thinning caused by the acceleration in flow of both glaciers. Peak rates of change, including thinning rates of similar to 90 m yr(-1), coincided with the rapid increases in flow speed. Extrapolation of the measured data to the ice divides yields an estimated combined catchment volume loss …

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Assessment Of The Impact Of Various Ionospheric Models On High Frequency Signal Raytracing, Joshua T. Werner Mar 2007

Assessment Of The Impact Of Various Ionospheric Models On High Frequency Signal Raytracing, Joshua T. Werner

Theses and Dissertations

An assessment of the impact of various ionospheric models on high-frequency (HF) signal raytracing is presented. Ionospheric refraction can strongly affect the propagation of HF signals. Consequently, Department of Defense missions such as over-the-horizon RADAR, HF communications, and geo-location all depend on an accurate specification of the ionosphere. Five case studies explore ionospheric conditions ranging from quiet conditions to solar flares and geomagnetic storms. It is shown that an E layer by itself can increase an HF signal’s ground range by over 100 km, stressing the importance of accurately specifying the lower ionosphere. It is also shown that the GPSII …

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Spacecraft Proximity Operations Used To Estimate The Dynamical & Physical Properties Of A Resident Space Object, Abraham F. Brunner Mar 2007

Spacecraft Proximity Operations Used To Estimate The Dynamical & Physical Properties Of A Resident Space Object, Abraham F. Brunner

Theses and Dissertations

When conducting a space proximity operation, developing high-fidelity estimates of the dynamical and physical properties of a Resident Space Object (RSO) based on post-rendezvous observational data acquired, is imperative for the understanding of the RSO itself and the operating environment. This research investigates the estimation of relative motion dynamics, rotational dynamics, and the feasibility of estimating the moments of inertia of a RSO. Using the Hill-Clohessy-Wiltshire equations, rigid-body dynamics, and estimation theory, a nonlinear least squares estimation algorithm is implemented in the processing of range data from tracked observation points on the RSO body. Through simulation, it was determined that …

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Anisotropy In The South Atlantic Anomaly, Shaun M. Easley Mar 2007

Anisotropy In The South Atlantic Anomaly, Shaun M. Easley

Theses and Dissertations

From June 2000 through July 2006, the TSX-5 satellite measured proton fluxes in the Earth’s magnetosphere using its CEASE instrument. A review of the satellite data by scientists at AFRL/VSBX revealed an unanticipated, recurring bi-modal structure in histograms of the proton counts. This research identified the bi-modal behavior as anisotropic in nature, and the result of two separate processes. At low altitudes the anisotropy was well described by the classic “East-West Effect.” Comparisons of the satellite data to simple analytical models are presented. At high altitudes, the anisotropy was the result of the detector measuring protons at different pitch angles …

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Practicable Enhancement Of Spontaneous Emission Using Surface Plasmons, Greg Sun, Jacob B. Khurgin, Richard A. Soref Mar 2007

Practicable Enhancement Of Spontaneous Emission Using Surface Plasmons, Greg Sun, Jacob B. Khurgin, Richard A. Soref

Physics Faculty Publications

The authors develop a rigorous theory of the enhancement of spontaneous emission from a light emitting device via coupling the radiant energy in and out of surface plasmon polaritons (SPPs) on the metal-dielectric interface. Using the GaN/Ag system as an example, the authors show that using SPP pays off only for emitters that have a low luminescence efficiency.

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The Origins Of Four Paterae Of Malea Planum, Mars, Susan K. Larson Mar 2007

The Origins Of Four Paterae Of Malea Planum, Mars, Susan K. Larson

Theses and Dissertations

Malea Planum is a volcanic plain on the southern rim of Hellas Planitia, the largest impact basin on Mars. Four large circular structures on Malea Planum have traditionally been identified as paterae, or low relief, central vent volcanoes (Plescia and Saunders, 1979). A geologic map was constructed and new crater counts made to explore the ages and origins of the paterae. Amphitrites and Peneus Paterae have radial patterns of wrinkle ridges on their flanks and distinct summit calderas (95 km and 130 km across) with arcuate bounding scarps. In contrast, Malea and Pityusa Paterae are broad depressions with diameters greater …

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Dynamics And Instabilities Of Defects In Two-Dimensional Crystals On Curved Backgrounds, Mark Bowick, Homin Shin, Alex Travesset Mar 2007

Dynamics And Instabilities Of Defects In Two-Dimensional Crystals On Curved Backgrounds, Mark Bowick, Homin Shin, Alex Travesset

Physics - All Scholarship

Point defects are ubiquitous in two dimensional crystals and play a fundamental role in determining their mechanical and thermodynamical properties. When crystals are formed on a curved background, finite length grain boundaries (scars) are generally needed to stabilize the crystal. We provide a continuum elasticity analysis of defect dynamics in curved crystals. By exploiting the fact that any point defect can be obtained as an appropriate combination of disclinations, we provide an analytical determination of the elastic spring constants of dislocations within scars and compare them with existing experimental measurements from optical microscopy. We further show that vacancies and interstitials, …

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Formation Of Single Crystalline Zno Nanotubes Without Catalysts And Templates, Samuel Mensah, Vijaya Kayastha, Ilia Ivanov, David Geohegan, Yoke Khin Yap Mar 2007

Formation Of Single Crystalline Zno Nanotubes Without Catalysts And Templates, Samuel Mensah, Vijaya Kayastha, Ilia Ivanov, David Geohegan, Yoke Khin Yap

Department of Physics Publications

Oxide and nitride nanotubes have gained attention for their large surface areas, wide energy band gaps, and hydrophilic natures for various innovative applications. These nanotubeswere either grown by templates or multistep processes with uncontrollable crystallinity. Here the authors show that single crystal ZnO nanotubes can be directly grown on planar substrates without using catalysts and templates. These results are guided by the theory of nucleation and the vapor-solid crystal growth mechanism, which is applicable for transforming other nanowires or nanorods into nanotubular structures.

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Large Seasonal Swings In Leaf Area Of Amazon Rainforests, Ranga B. Myneni, Wenze Yang, Ramakrishna R. Nemani, Alfredo R. Huete, Robert E. Dickinson, Yuri Knyazikhin, Kamel Didan, Rong Fu, Robinson I. Negron Juarez, Sasan S. Saatchi, Hirofumi Hashimoto, Kazuhito Ichii, Nikolay V. Shabanov, Bin Tan, Piyachat Ratana, Jeffrey L. Privette, Jeffrey T. Morisette, Eric F. Vermote, David P. Roy, Robert E. Wolfe, Mark A. Friedl, Steven W. Running, Petr Votava, Nazmi El-Saleous, Sadashiva Devadiga, Yin Su, Vincent V. Salomonson Mar 2007

Large Seasonal Swings In Leaf Area Of Amazon Rainforests, Ranga B. Myneni, Wenze Yang, Ramakrishna R. Nemani, Alfredo R. Huete, Robert E. Dickinson, Yuri Knyazikhin, Kamel Didan, Rong Fu, Robinson I. Negron Juarez, Sasan S. Saatchi, Hirofumi Hashimoto, Kazuhito Ichii, Nikolay V. Shabanov, Bin Tan, Piyachat Ratana, Jeffrey L. Privette, Jeffrey T. Morisette, Eric F. Vermote, David P. Roy, Robert E. Wolfe, Mark A. Friedl, Steven W. Running, Petr Votava, Nazmi El-Saleous, Sadashiva Devadiga, Yin Su, Vincent V. Salomonson

GSCE Faculty Publications

Despite early speculation to the contrary, all tropical forests studied to date display seasonal variations in the presence of new leaves, flowers, and fruits. Past studies were focused on the timing of phenological events and their cues but not on the accompanying changes in leaf area that regulate vegetation–atmosphere exchanges of energy, momentum, and mass. Here we report, from analysis of 5 years of recent satellite data, seasonal swings in green leaf area of ~25% in a majority of the Amazon rainforests. This seasonal cycle is timed to the seasonality of solar radiation in a manner that is suggestive of …

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Portable Diode Pumped Femtosecond Laser, David A. Jones Mar 2007

Portable Diode Pumped Femtosecond Laser, David A. Jones

Theses and Dissertations

This thesis discusses the work to make ultrashort pulsed lasers smaller and more economical. While sharing many of the basic properties of normal beam optics there are some specific properties in both creating and exploiting those pulses that must be understood. The discussion will focus on mode locking as the primary way of producing ultrashort pulses. Particular attention will be paid to intracavity group velocity dispersion and how to correct it inside the cavity. The discussion then turns to the basis of our work including initial cavity design and component selection with focus on the specific crystals used in the …

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Development Of A Screening Model For Design And Costing Of An Innovative Tailored Granular Activated Carbon Technology To Treat Perchlorate-Contaminated Water, William C. Powell Mar 2007

Development Of A Screening Model For Design And Costing Of An Innovative Tailored Granular Activated Carbon Technology To Treat Perchlorate-Contaminated Water, William C. Powell

Theses and Dissertations

Perchlorate contamination of drinking water is a problem that has recently gained national attention. The purpose of this research was to develop a tool to predict the cost and performance of tailored granular activated carbon (T-GAC), an innovative technology to treat perchlorate-contaminated water. The ability to predict cost and performance is essential to promote transfer and commercialization of innovative technologies. This study investigated how data obtained from small-scale laboratory tests could be applied to predict cost and performance of a full-scale T-GAC system to treat perchlorate-contaminated water. A technology model was developed using GAC design principles and using a multi-component …

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Use Of Tabu Search In A Solver To Map Complex Networks Onto Emulab Testbeds, Jason E. Macdonald Mar 2007

Use Of Tabu Search In A Solver To Map Complex Networks Onto Emulab Testbeds, Jason E. Macdonald

Theses and Dissertations

The University of Utah's solver for the testbed mapping problem uses a simulated annealing metaheuristic algorithm to map a researcher's experimental network topology onto available testbed resources. This research uses tabu search to find near-optimal physical topology solutions to user experiments consisting of scale-free complex networks. While simulated annealing arrives at solutions almost exclusively by chance, tabu search incorporates the use of memory and other techniques to guide the search towards good solutions. Both search algorithms are compared to determine whether tabu search can produce equal or higher quality solutions than simulated annealing in a shorter amount of time. It …

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Hydrodynamic And Rheology Of Active Polar Filaments, Tanniemola B. Liverpool, M. Cristina Marchetti Mar 2007

Hydrodynamic And Rheology Of Active Polar Filaments, Tanniemola B. Liverpool, M. Cristina Marchetti

Physics - All Scholarship

The cytoskeleton provides eukaryotic cells with mechanical support and helps them perform their biological functions. It is a network of semiflexible polar protein filaments and many accessory proteins that bind to these filaments, regulate their assembly, link them to organelles and continuously remodel the network. Here we review recent theoretical work that aims to describe the cytoskeleton as a polar continuum driven out of equilibrium by internal chemical reactions. This work uses methods from soft condensed matter physics and has led to the formulation of a general framework for the description of the structure and rheology of active suspension of …

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An Approach In Identifying And Tracing Back Spoofed Ip Packets To Their Sources, Krishnun Sansurooah Mar 2007

An Approach In Identifying And Tracing Back Spoofed Ip Packets To Their Sources, Krishnun Sansurooah

Australian Digital Forensics Conference

With internet expanding in every aspect of businesses infrastructure, it becomes more and more important to make these businesses infrastructures safe and secure to the numerous attacks perpetrated on them conspicuously when it comes to denial of service (DoS) attacks. A Dos attack can be summarized as an effort carried out by either a person or a group of individual to suppress a particular outline service. This can hence be achieved by using and manipulating packets which are sent out using the IP protocol included into the IP address of the sending party. However, one of the major drawbacks is …

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Mood 300 Iptv Decoder Forensics, An Hilven Mar 2007

Mood 300 Iptv Decoder Forensics, An Hilven

Australian Digital Forensics Conference

Since June 2005, viewers in Belgium can get access digital TV or IPTV available via ADSL through Belgacom, the largest telecommunications provider in the country. The decoders used to enjoy these services are the Mood 300 series from Tilgin (formerly i3 Micro Technology). As of the Mood 337, the decoders contain a hard disk to enable the viewer to record and pause TV programs. Although it is publicly known that the Mood’s hard disk is used to save recorded and paused TV programs, it was still unknown if it contains any data that could be of interest during a forensic …

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Tracing Usb Device Artefacts On Windows Xp Operating System For Forensic Purpose, Victor Chileshe Luo Mar 2007

Tracing Usb Device Artefacts On Windows Xp Operating System For Forensic Purpose, Victor Chileshe Luo

Australian Digital Forensics Conference

On Windows systems several identifiers are created when a USB device is plugged into a universal serial bus. Some of these artefacts or identifiers are unique to the device and consistent across different Windows platforms as well as other operating systems such as Linux. Another key factor that makes these identifiers forensically important is the fact that they are traceable even after the system has been shut down. Hence they can be used in forensic investigations to identify specific devices that have been connected to the system in question

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Introduction To Mobile Phone Flasher Devices And Considerations For Their Use In Mobile Phone Forensics, Marwan Al-Zarouni Mar 2007

Introduction To Mobile Phone Flasher Devices And Considerations For Their Use In Mobile Phone Forensics, Marwan Al-Zarouni

Australian Digital Forensics Conference

The paper gives an overview of mobile phone flasher devices and their use for servicing mobile phones, their illegitimate uses and their use in mobile phone forensics. It discusses the different varieties of flasher devices and the differences between them. It also discusses the shortcomings of conventional mobile forensics software and highlights the need for the use of flasher devices in mobile forensics to compensate for the shortcomings. The paper then discusses the issues with the use of flasher devices in mobile forensics and precautions and considerations of their use. The paper goes further to suggest means of testing the …

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The Effectiveness Of Investigative Tools For Secure Digital (Sd) Memory Card Forensics, Haitham Al-Hajri, Patricia Williams Mar 2007

The Effectiveness Of Investigative Tools For Secure Digital (Sd) Memory Card Forensics, Haitham Al-Hajri, Patricia Williams

Australian Digital Forensics Conference

There are many freeware based tools that can be downloaded from the World Wide Web. This paper reports the retrieval results of using these tools on digital images which have been deleted from Secure Digital (SD) cards. Since SD cards and USB flash drives are considered solid state technology, the tools selected are specifically for solid state drives. This research helps classify the selection of the most effective freeware tools that could be used to recover lost or deleted images. Further, it includes some of the issues that would face forensic examiners undertaking such investigations. The tools were tested using …

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Id Theft: A Computer Forensics' Investigation Framework, Olga Angelopoulou Mar 2007

Id Theft: A Computer Forensics' Investigation Framework, Olga Angelopoulou

Australian Digital Forensics Conference

The exposure of online identities grows rapidly nowadays and so does the threat of having even more impersonated identities. Internet users provide their private information on multiple web-based agents for a number of reasons, online shopping, memberships, social networking, and many others. However, the number of ID Theft victims grows as well, resulting to the growth of the number of incidents that require computer forensics investigation in order to resolve this type of crime. For this reason, it appears of value to provide a systematic approach for the computer forensics investigators aiming to resolve such type of computer based ID …

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Pocket Sdv With Sdguardian: A Secure & Forensically Safe Portable Execution Environment, Peter Hannay, Peter James Mar 2007

Pocket Sdv With Sdguardian: A Secure & Forensically Safe Portable Execution Environment, Peter Hannay, Peter James

Australian Digital Forensics Conference

Storage of sensitive and/or business critical data on portable USB attachable mass storage devices is a common practice. The ability to transport large volumes of data from the standard place of work and then access and process the data on an available PC at a different location provides both convenience and flexibility. However, use of such USB attachable mass storage devices presents two major security risks; the risk of loss of the portable storage device during transport and the risk of data remnants residing on a PC after accessing the data from the USB storage device. The latter risk is …

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Can Sdv Technology Be Utilised In A Smartphone To Prevent Forensic Analysis?, Peter James Mar 2007

Can Sdv Technology Be Utilised In A Smartphone To Prevent Forensic Analysis?, Peter James

Australian Digital Forensics Conference

Eliminating the opportunities to successfully acquire data from mobile devices is a critical security objective for certain organisations. In particular, Government agencies require assurance that classified data is secured against hostile forensic analysis. The Secure Systems Silicon Data Vault (SDV) is a hardware based data encryption and access control device that has been accredited by the Australian Government to secure classified information held on laptops and portable hard disk drives; hardware is recognised as a superior trusted platform to implement security mechanisms. The SDV’s 128bit Advanced Encryption Standard (AES) cryptography, sophisticated key management & access controls and total disk encryption …

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Anti-Forensics And The Digital Investigator, Gary C. Kessler Mar 2007

Anti-Forensics And The Digital Investigator, Gary C. Kessler

Australian Digital Forensics Conference

Viewed generically, anti-forensics (AF) is that set of tactics and measures taken by someone who wants to thwart the digital investigation process. This paper describes some of the many AF tools and methods, under the broad classifications of data hiding, artefact wiping, trail obfuscation, and attacks on the forensics tools themselves. The concept of AF is neither new nor solely intended to be used by the criminal class; it also has legitimate use by those who wish to protect their privacy. This paper also introduces the concept of time-sensitive anti-forensics, noting that AF procedures might be employed for the sole …

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Extracting Inter-Arrival Time Based Behaviour From Honeypot Traffic Using Cliques, Saleh Almotairi, Andrew Clark, Marc Dacier, Corrado Leita, George Mohay, Van Hau Pham, Olivier Thonnard, Jacob Zimmermann Mar 2007

Extracting Inter-Arrival Time Based Behaviour From Honeypot Traffic Using Cliques, Saleh Almotairi, Andrew Clark, Marc Dacier, Corrado Leita, George Mohay, Van Hau Pham, Olivier Thonnard, Jacob Zimmermann

Australian Digital Forensics Conference

The Leurre.com project is a worldwide network of honeypot environments that collect traces of malicious Internet traffic every day. Clustering techniques have been utilized to categorize and classify honeypot activities based on several traffic features. While such clusters of traffic provide useful information about different activities that are happening in the Internet, a new correlation approach is needed to automate the discovery of refined types of activities that share common features. This paper proposes the use of packet inter-arrival time (IAT) as a main feature in grouping clusters that exhibit commonalities in their IAT distributions. Our approach utilizes the cliquing …

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Multi-Step Scenario Matching Based On Unification, Soroto Panichprecha, George Mohay, Andrew Clark Mar 2007

Multi-Step Scenario Matching Based On Unification, Soroto Panichprecha, George Mohay, Andrew Clark

Australian Digital Forensics Conference

This paper presents an approach to multi-step scenario specification and matching, which aims to address some of the issues and problems inherent in to scenario specification and event correlation found in most previous work. Our approach builds upon the unification algorithm which we have adapted to provide a seamless, integrated mechanism and framework to handle event matching, filtering, and correlation. Scenario specifications using our framework need to contain only a definition of the misuse activity to be matched. This characteristic differentiates our work from most of the previous work which generally requires scenario specifications also to include additional information regarding …

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Steganalysis In Computer Forensics, Ahmed Ibrahim Mar 2007

Steganalysis In Computer Forensics, Ahmed Ibrahim

Australian Digital Forensics Conference

Steganography deals with secrecy and convert communication and today the techniques for countering this in the context of computer forensics has somewhat fallen behind. This paper will discuss on how steganography is used for information hiding and its implications on computer forensics. While this paper is not about recovering hidden information, tools that are used for both steganography and steganalysis is evaluated and identifies the shortcomings that the forensic analysts would face. In doing so this paper urges on what the stakeholders in the field of computer forensics needs to do to keep ahead of criminals who are using such …

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Managing Digital Forensic Knowledge An Applied Approach, David P. Biros, Mark Weiser, John Witfield Mar 2007

Managing Digital Forensic Knowledge An Applied Approach, David P. Biros, Mark Weiser, John Witfield

Australian Digital Forensics Conference

The science of digital forensics is continually changing as technological advances are made and new digital devices are developed. This environment forces analysts to regularly extend their skills with training and frequent research to develop new and admissible techniques. Unfortunately, the same and similar methods are re-discovered by other analysts who are unaware of earlier peer efforts. The situation is aggravated by a nearly universal backlog in qualified digital forensics facilities. This leaves little time for communication between analysts even within a single agency. To address these issues and facilitate an increase in efficiency across all law enforcement agencies, we …

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Oops They Did It Again: The 2007 Australian Study Of Remnant Data Contained On 2nd Hand Hard Disks, Craig Valli, Andrew Woodward Mar 2007

Oops They Did It Again: The 2007 Australian Study Of Remnant Data Contained On 2nd Hand Hard Disks, Craig Valli, Andrew Woodward

Australian Digital Forensics Conference

The 2007 study used a biased selection process where the primary focus was the purchase of high-speed SCSI drives and drive packs, in addition 2.5 inch laptop drives were targeted. Conventional IDE based hard drives were also examined in the study. A total of 84 drives were examined this year, 23 yielded data that represented significant and in some cases profound exposure if data. Encouragingly more hard disks were erased in this study than in previous studies. However, there is still a significant gap in erasure procedures in organisations, which is particularly concerning given that the drives were from large …

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Adsl Router Forensics Part 1: An Introduction To A New Source Of Electronic Evidence, Patryk Szewczyk Mar 2007

Adsl Router Forensics Part 1: An Introduction To A New Source Of Electronic Evidence, Patryk Szewczyk

Australian Digital Forensics Conference

Currently there appears to be a lack of research in the area of developing tools, testing methodologies, and creating standards for ADSL router forensics. The paper examines a wide range of literature and introduces the concept of ADSL router forensics as a new and potential field of research for digital forensics investigators. It begins by examining why there is a need for router forensics by detailing some of the more common threats which consumers may experience while online. An outline will be provided discussing the feasibility, limitations and potential risks of router forensics. The paper will then examine one possible …

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An Examination Of The Asus Wl-Hdd 2.5 As A Nepenthes Malware Collector, Patryk Szewczyk Mar 2007

An Examination Of The Asus Wl-Hdd 2.5 As A Nepenthes Malware Collector, Patryk Szewczyk

Australian Digital Forensics Conference

The Linksys WRT54g has been used as a host for network forensics tools for instance Snort for a long period of time. Whilst large corporations are already utilising network forensic tools, this paper demonstrates that it is quite feasible for a non-security specialist to track and capture malicious network traffic. This paper introduces the Asus Wireless Hard disk as a replacement for the popular Linksys WRT54g. Firstly, the Linksys router will be introduced detailing some of the research that was undertaken on the device over the years amongst the security community. It then briefly discusses malicious software and the impact …

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Blogs: Anti-Forensics And Counter Anti-Forensics, Glenn S. Dardick, Claire R. La Roche, Mary A. Flanigan Mar 2007

Blogs: Anti-Forensics And Counter Anti-Forensics, Glenn S. Dardick, Claire R. La Roche, Mary A. Flanigan

Australian Digital Forensics Conference

Blogging gives an ordinary person the ability to have a conversation with a wide audience and has become one of the fastest growing uses of the Web. However, dozens of employee-bloggers have been terminated for exercising what they consider to be their First Amendment right to free speech and would-be consumer advocates face potential liability for voicing their opinions. To avoid identification and prevent retribution, bloggers have sought to maintain anonymity by taking advantage of various tools and procedures - anti-forensics. Unfortunately some anonymous bloggers also post content that is in violation of one or more laws. Some blogging content …

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