abstract: The Web is one of the most exciting and dynamic areas of development in today’s technology. However, with such activity, innovation, and ubiquity have come a set of new challenges for digital forensic examiners, making their jobs even more difficult. For examiners to become as effective with evidence from the Web as they currently are with more traditional evidence, they need (1) methods that guide them to know how to approach this new type of evidence and (2) tools that accommodate web environments’ unique characteristics. In this dissertation, I present my research to alleviate the difficulties forensic examiners currently face with respect to evidence originating from web environments. First, I introduce a framework for web environment forensics, which elaborates on and addresses the key challenges examiners face and outlines a method for how to approach web-based evidence. Next, I describe my work to identify extensions installed on encrypted web thin clients using only a sound understanding of these systems’ inner workings and the metadata of the encrypted files. Finally, I discuss my approach to reconstructing the timeline of events on encrypted web thin clients by using service provider APIs as a proxy for directly analyzing the device. In each of these research areas, I also introduce structured formats that I customized to accommodate the unique features of the evidence sources while also facilitating tool interoperability and information sharing. / Dissertation/Thesis / Doctoral Dissertation Computer Science 2017

Då datorer i alla dess former har kommit att bära betydande mängder relevant information för diverse forensiska utredningar så krävs en ingående kunskap gällande hur denna data lämpligast infångas. En typ av klient som nyligen har gjort sitt kommersiella intåg på marknaden är den internetbaserade tunna klienten. Det existerar i dagsläget begränsat med underlag gällande huruvida en sådan klient bär information som är relevant för en IT-forensisk utredning. Inom denna uppsats har därför en internetbaserad tunn klient av typen Chromebook varit mål för undersökning. Syftet har varit att kartlägga vilka sårbarheter som existerar, samt om möjligt huruvida dessa kan brukas som underlag vid en forensisk utredning. För detta ändamål har klientens lagrings- samt kommunikationsmönster analyserats. För genomförandet av detta brukades experimentella metodiker i form av penetrationstest samt IT-forensisk undersökning. Det har även kartlagts huruvida programvaror avsedda för operativsystemet Linux kan exekveras på klienten. Ändamålet med detta var att fastställa om klientens volatila minne kan utvinnas med hjälp av verktyg för just Linux. Rapportens resultat påvisar att det inom en klient av denna typ finns forensiskt värdefull information att inhämta. Det påvisas även att Chrome OS från en användares perspektiv kan anses som säkert. / Computers in various forms have come to carry a significant amount of relevant information for various forensic investigations. Therefore, detailed knowledge is required regarding how this data is best acquired. One type of client that has recently made its entry onto the commercial market is the Web Thin Client. As it is today, only a limited amount of relevant information can be found regarding in what capacity such a client contains data that is relevant to an IT-forensic investigation. For this reason, a Web thin client of the model Google Chromebook has been evaluated in this paper. The purpose of this examination has been to identify the vulnerabilities that currently exist, and if possible whether these can be used as a basis for a forensic investigation. To achieve this, the client's storage and communication patterns have been analyzed by implementation of experimental methodologies. The methods used for the purpose are penetration testing and an IT forensic investigation. Tests have also been performed to evaluate whether software for the Linux operating system can be executed on the client. The purpose of this was to determine whether the client's volatile memory can be extracted using tools created for Linux. The results presented in this paper demonstrate the fact that within a client of this type, valuable forensic information can be located. It is also established that Chrome OS from a user's perspective can be considered as safe.