Social networks are popular platforms that simplify user interaction and encourage collaboration. They collect large amounts of media from their users, often reported from mobile devices. The value and impact of social media makes it however an attractive attack target. In this thesis, we focus on the following social media vulnerabilities. First, review centered social networks such as Yelp and Google Play have been shown to be the targets of significant search rank and malware proliferation attacks. Detecting fraudulent behaviors is thus paramount to prevent not only public opinion bias, but also to curb the distribution of malware. Second, the increasing use of mobile visual data in news networks, authentication and banking applications, raises questions of its integrity and credibility. Third, through proof-of- concept implementations, we show that data reported from wearable personal trackers is vulnerable to a wide range of security and privacy attacks, while off-the-shelves security solutions do not port gracefully to the constraints introduced by trackers. In this thesis we propose novel solutions to address these problems. First, we introduce Marco, a system that leverages the wealth of spatial, temporal and network information gleaned from Yelp, to detect venues whose ratings are impacted by fraudulent reviews. Second, we propose FairPlay, a system that correlates review activities, linguistic and behavioral signals gleaned from longitudinal app data, to identify not only search rank fraud but also malware in Google Play, the most popular Android app market. Third, we describe Movee, a motion sensor based video liveness verification system, that analyzes the consistency between the motion inferred from the simultaneously and independently captured camera and inertial sensor streams. Finally, we devise SensCrypt, an efficient and secure data storage and communication protocol for affordable and lightweight personal trackers. We provide the correctness and efficacy of our solutions through a detailed theoretic and experimental analysis.

Aujourd’hui, il n’est pas rare qu’une personne se trouve en position de faiblesse lorsqu’elle contracte. Une entreprise en situation de dépendance économique, un consommateur face à un professionnel, l’utilisation de plus en plus fréquente de contrats d’adhésion, sont autant de facteurs pouvant conduire à la vulnérabilité d’un contractant. Le risque est alors que la partie dite « forte » abuse de sa position pour pousser l’autre à s’engager dans une convention fortement déséquilibrée, profitant essentiellement à l’auteur de l’abus. Ce type blâmable de comportement se manifestant lors de la formation des contrats, la partie lésée devrait pouvoir trouver une protection à travers la théorie des vices du consentement. Toutefois, cette théorie se révèle aujourd’hui inadaptée pour protéger efficacement les contractants victimes d’abus. Ce constat s’explique principalement par le fait qu’elle est restée inchangée depuis 1804. Basée sur une conception individualiste du contrat, les conditions d’admission propres à chaque vice, que sont l’erreur, la violence et le dol, sont trop restrictives. Or, les inégalités contractuelles étant à ce jour plus prononcées, elles entraînent nécessairement davantage d’abus, c’est pourquoi il convient de restaurer une telle théorie pour protéger comme il se doit les contractants. C’est à travers la notion de dol que nous proposons de le faire. Ce choix n’est pas le fruit du hasard. Il se justifie par le fait que le dol est un délit civil, avant même d’être un vice du consentement. Plus précisément, il est la manifestation de la déloyauté précontractuelle. Le consacrer comme un fait altérant la volonté engendre alors deux effets négatifs. Le premier tient au fait qu’il apparaît, en droit positif, comme une notion complexe, source de contradictions. Le second consiste à ne pouvoir réprimer la malhonnêteté perpétrée lors de la formation des contrats que de manière imparfaite et ce, en raison du champ d’application trop restreint du dol, celui-ci étant cantonné à une erreur provoquée. En lui redonnant sa véritable nature, celle de délit civil viciant le contrat, id est d’atteinte à la bonne foi précontractuelle, on remédierait à ces deux imperfections. / Professional, or the increasing use of adhesion contracts (“take it or leave it agreements”), all are factors that can lead to the contractor’s vulnerability. The risk is, for the so-called “strong” party, to abuse its position in order to force the other party into a strongly unbalanced agreement, mainly in its own benefit. Since such a reprehensible behavior occurs during the contract formation, the weakened party should be able to find protection through the use of the defects of consent theory. However, this theory has proven inadequate to effectively protect abused contractors today. A major explanation is due to the fact that this theory remains unchanged since 1804. Based on an individualistic conception of the contract, conditions of admission of each defects of consent, such as error, abuse and fraud, are too restrictive. However, the more contractual inequalities exist, the more they will turn into abuse. Therefore, this is why such a theory should be restored in order to protect contractors. It is through the notion of “dol” (willful misrepresentation or fraudulent concealment) that we propose to do so. This choice is not a coincidence. It is justified by the fact that “dol” is a tort, even before being a defect of consent. Specifically, it is the manifestation of pre-contractual disloyalty. Its recognition as a fact altering willpower will generate two negative effects. The first is linked to the fact that “dol” appears to be a complex notion and a source of contradiction in substantive law. The second is not permitting to properly penalize the dishonesty perpetrated during the contract formation due to a too narrow scope of the “dol”, the latter being understood as an induced error. Giving it back its real nature of a civil tort defecting the contract and undermining the pre-contractual good faith, our work aims at finding a remedy to these two shortcomings.

El presente informe aborda sobre dos controversias judiciales tanto en el ámbito privado como en el público, sobre la materia de otorgamiento de escritura pública y reposición por despido laboral, respectivamente. El Expediente N° 1969-2016-0-0401-JR-CI-09, expediente privado, abarca sobre una demanda de otorgamiento de escritura pública de un contrato de promesa de compraventa de un local comercial ubicado en la ciudad de Arequipa. La controversia principal corresponde a si el contrato celebrado entre la compradora primigenia y los demandados se trataría de un contrato de promesa de compraventa o un contrato definitivo, y como consecuencia, si la transferencia realizada por dicha compradora primigenia a la demandante se trataría de una cesión de posición contractual o de una cesión de derechos. El Noveno Juzgado Especializado en lo Civil y la Segunda Sala Civil, emitieron sentencias contradictorias, estando de acuerdo respecto a que el contrato de promesa de compraventa se trataría de un contrato definitivo; sin embargo, discrepan respecto al segundo punto, toda vez que la primera de las mencionadas señala que la transferencia del inmueble materia de litis se habría realizado a través de una cesión de posición contractual y no a través de una cesión de derechos como señala la Segunda Sala Civil. Por otro lado, el Expediente N° 03489-2014-0-1801-JR-LA-08 abarca sobre una demanda de reposición laboral, toda vez que la demandante alude que la despidieron fraudulentamente por “haber participado en una pelea de agresión mutua verbal y física”, considerado falta grave establecida en el inciso f) del artículo 25 del D.S. N° 093-97-TR, en contra de una trabajadora de otra empresa, mientras se encontraba de vacaciones y en un lugar distinto al de su lugar de trabajo. En ese sentido, la controversia principal del mencionado expediente es determinar si el despido se encontraba realmente justificado o no. Al respecto, el Octavo Juzgado Especializado Permanente de Trabajo y la Cuarta Sala Laboral Permanente de Lima emitieron sentencias contradictorias, donde la primera de las mencionadas señala que no se ha acreditado objetivamente la falta grave imputada a la demandante por lo que corresponde la reposición laboral; a diferencia de lo señalado por la Cuarta Sala Laboral Permanente de Lima quien establece que si se produjo la mencionada falta grave. Finalmente, la demandante interpone recurso de casación, la misma que es declarada improcedente toda vez que pretende una nueva valoración de hechos ya analizados en la Sentencia de Vista. / This report deals with two legal disputes, both in the private and public scope, about granting of a Public Deed and replenishing for labor dismissal, respectively. File No. 1969-2016-0-0401-JR-CI-09, private file, is about a demand for the granting of a Public Deed of a sale promise contract of a commercial property located in the city of Arequipa. The main controversy corresponds to whether the contract between the original purchaser and the defendants was a sale promise contract or a definitive contract, and therefore, whether the transfer made by the original purchaser to the plaintiff was an assignment of contractual position or an assignment of rights. The Ninth Specialized Civil Court and the Second Civil Chamber issued contradictory judgments, both agreeing that the sale promise contract is a definitive contract; however, they differ about the second point, in which the first one indicates that the transfer of the property subject to litis would have been carried out through a transfer of contractual position and not through the assignment of rights, as indicated by the Second Civil Chamber. On the other hand, File N° 03489-2014-0-1801-JR-LA-08 is about a demand for replenishing for labor dismissal, in which the plaintiff argues that she was fraudulently fired for “having participated in a fight of mutual verbal and physical aggression”, considered a serious misconduct according with paragraph f) of article 25 of the Supreme Decree N° 093-97-TR, against a worker from another company while she was on vacation in place different than her workplace. In that sense, the main controversy of the mentioned file is to clarify whether the dismissal was really justified or not. In this regard, the Eighth Permanent Specialized Labor Court and the Fourth Permanent Labor Chamber of Lima issued contradictory judgments as well, in which the first indicated that the serious misconduct charged to the plaintiff has not been objectively proved and therefore it corresponds the replenishing; unlike what was indicated by the Fourth Permanent Labor Chamber of Lima which established that the serious misconduct aforementioned occurred. Finally, the plaintiff filed a cassation appeal which was declared inadmissible since it pretended a new analysis of facts which was already done in the judgment issued by the second instance court. / Trabajo de suficiencia profesional

The dissertation thesis at large discusses the problems of unlawful conduct in the economic area, possibilities for its exposure and prevention issues. Every human conduct, apart from the legal viewpoint, may also be assessed from the moral viewpoint, whereas in this context, law is designated as the "moral minimum". From this relationship, we arrive at the conclusion that every instance of unlawful conduct is also immoral. On the contrary, conduct that complies with the law always need not be in compliance with the moral norms. In the Czech Republic, the New Criminal Code came into force on 1 January 2010, which also punishes the most severe forms of unlawful conduct and fundamentally affects performance of the accounting and auditing professions. Apart from some concept changes, this Codex also introduced, for instance, changes in the punishability of planning crimes. From the viewpoint of the auditor, tax adviser and accountant, barring of perpetration, whose commitment or planning authentically comes to the knowledge of the auditor, tax adviser or accountant seems to be fundamental. The issues of occupational fraud are mainly related to the problems of the auditing profession. These unlawful acts take various forms, which can be split into three basic groups, which are asset misappropriation, fraudulent statements and corruption. When exposing occupational fraud, as well as other forms of unlawful conduct, confidentiality issues are fundamental. In some cases, the law anticipates breaking through this confidentiality, mainly, for the purpose of exposing the most severe forms of unlawful conduct. Within the framework of prevention of occupational fraud, internal control systems play an essential role. It is possible to evaluate the existence of ethical codices, respectively, building of ethical corporate culture as very fundamental.

增長層級式自我組織映射網路(GHSOM)屬於一種非監督式類神經網路，為自我組織映射網路(SOM)的延伸，擅長於對樣本分群，以輔助分析樣本族群裡的共同特徵，並且可以透過族群間存在的空間關係假設來建立分類器，進而辨別出異常的資料。 因此本研究提出一個創新的對偶方法(即為一個建立決策支援系統架構的方法)分別對舞弊與非舞弊樣本分群，首先兩類別之群組會被配對，即辨識某一特定無弊群體的非舞弊群體對照組，針對這些配對族群，套用基於不同空間假設所設立的分類規則以檢測舞弊與非舞弊群體中是否有存在某種程度的空間關係，此外並對於舞弊樣本的分群結果加入特徵萃取機制。分類績效最好的分類規則會被用來偵測受測樣本是否有舞弊的嫌疑，萃取機制的結果則會用來標示有舞弊嫌疑之受測樣本的舞弊行為特徵以及相關的輸入變數，以做為後續的決策輔助。 更明確地說，本研究分別透過非舞弊樣本與舞弊樣本建立一個非舞弊GHSOM樹以及舞弊GHSOM樹，且針對每一對GHSOM群組建立分類規則，其相應的非舞弊/舞弊為中心規則會適應性地依循決策者的風險偏好最佳化調整規則界線，整體而言較優的規則會被決定為分類規則。非舞弊為中心的規則象徵絕大多數的舞弊樣本傾向分布於非舞弊樣本的周圍，而舞弊為中心的規則象徵絕大多數的非舞弊樣本傾向分布於舞弊樣本的周圍。 此外本研究加入了一個特徵萃取機制來發掘舞弊樣本分群結果中各群組之樣本資料的共同特質，其包含輸入變數的特徵以及舞弊行為模式，這些資訊將能輔助決策者(如資本提供者)評估受測樣本的誠實性，輔助決策者從分析結果裡做出更進一步的分析來達到審慎的信用決策。 本研究將所提出的方法套用至財報舞弊領域(屬於財務舞弊偵測的子領域)進行實證，實驗結果證實樣本之間存在特定的空間關係，且相較於其他方法如SVM、SOM+LDA和GHSOM+LDA皆具有更佳的分類績效。因此顯示本研究所提出的機制可輔助驗證財務相關數據的可靠性。此外，根據SOM的特質，即任何受測樣本歸類到某特定族群時，該族群訓練樣本的舞弊行為特徵將可以代表此受測樣本的特徵推論。這樣的原則可以用來協助判斷受測樣本的可靠性，並可供持續累積成一個舞弊知識庫，做為進一步分析以及制定相關信用決策的參考。本研究所提出之基於對偶方法的決策支援系統架構可以被套用到其他使用財務數據為資料來源的財務舞弊偵測情境中，作為輔助決策的基礎。 / The Growing Hierarchical Self-Organizing Map (GHSOM) is extended from the Self-Organizing Map (SOM). The GHSOM’s unsupervised learning nature such as the adaptive group size as well as the hierarchy structure renders its availability to discover the statistical salient features from the clustered groups, and could be used to set up a classifier for distinguishing abnormal data from regular ones based on spatial relationships between them. Therefore, this study utilizes the advantage of the GHSOM and pioneers a novel dual approach (i.e., a proposal of a DSS architecture) with two GHSOMs, which starts from identifying the counterparts within the clustered groups. Then, the classification rules are formed based on a certain spatial hypothesis, and a feature extraction mechanism is applied to extract features from the fraud clustered groups. The dominant classification rule is adapted to identify suspected samples, and the results of feature extraction mechanism are used to pinpoint their relevant input variables and potential fraud activities for further decision aid. Specifically, for the financial fraud detection (FFD) domain, a non-fraud (fraud) GHSOM tree is constructed via clustering the non-fraud (fraud) samples, and a non-fraud-central (fraud-central) rule is then tuned via inputting all the training samples to determine the optimal discrimination boundary within each leaf node of the non-fraud (fraud) GHSOM tree. The optimization renders an adjustable and effective rule for classifying fraud and non-fraud samples. Following the implementation of the DSS architecture based on the proposed dual approach, the decision makers can objectively set their weightings of type I and type II errors. The classification rule that dominates another is adopted for analyzing samples. The dominance of the non-fraud-central rule leads to an implication that most of fraud samples cluster around the non-fraud counterpart, meanwhile the dominance of fraud-central rule leads to an implication that most of non-fraud samples cluster around the fraud counterpart. Besides, a feature extraction mechanism is developed to uncover the regularity of input variables and fraud categories based on the training samples of each leaf node of a fraud GHSOM tree. The feature extraction mechanism involves extracting the variable features and fraud patterns to explore the characteristics of fraud samples within the same leaf node. Thus can help decision makers such as the capital providers evaluate the integrity of the investigated samples, and facilitate further analysis to reach prudent credit decisions. The experimental results of detecting fraudulent financial reporting (FFR), a sub-field of FFD, confirm the spatial relationship among fraud and non-fraud samples. The outcomes given by the implemented DSS architecture based on the proposed dual approach have better classification performance than the SVM, SOM+LDA, GHSOM+LDA, SOM, BPNN and DT methods, and therefore show its applicability to evaluate the reliability of the financial numbers based decisions. Besides, following the SOM theories, the extracted relevant input variables and the fraud categories from the GHSOM are applicable to all samples classified into the same leaf nodes. This principle makes that the extracted pre-warning signal can be applied to assess the reliability of the investigated samples and to form a knowledge base for further analysis to reach a prudent decision. The DSS architecture based on the proposed dual approach could be applied to other FFD scenarios that rely on financial numbers as a basis for decision making.

Betrügerisches Verhalten bei geschlossenen Fonds ist in Deutschland Statistiken zufolge für jährliche Kapitalverluste im mittleren dreistelligen Millionenbereich verantwortlich. Der Gesetzgeber hat sich in der Vergangenheit wiederholt dem Problem angenommen und eine Vielzahl von zivil-, straf- und öffentlich-rechtlichen Maßnahmen zur Verbesserung des Anlegerschutzes auf den Weg gebracht, die mit dem Inkrafttreten des Kapitalanlagegesetzbuchs (KAGB) im Jahr 2013 ihren bisherigen Höhepunkt erreicht haben. Die Zweckdienlichkeit dieser Maßnahmen wird von Kritikern indes bezweifelt, darüber hinaus scheint sich in jüngerer Zeit ein neuartiges Phänomen des „sanktionslosen Betrugs“ auf dem Kapitalmarkt zu etablieren, bei dem es den Tätern gelingt entweder ohne, oder ohne nennenswerte Sanktionen – insbesondere in strafrechtlicher Hinsicht – davonzukommen. Als Beispiele seien hier die Debi Select Fonds aus Landshut sowie die POC-Fonds aus Berlin genannt, bei denen die im Hintergrund agierenden „Strippenzieher“ trotz millionenschwerer Anlegerschädigung weder in zivil- noch in strafrechtlicher Hinsicht zur Rechenschaft gezogen werden konnten. Die vorliegende Arbeit widmet sich der systematischen Erkundung dieses Phänomens, indem sie die Themenkomplexe „(sanktionslose) betrügerische geschlossene Fonds“ und „Anlegerschutz“ aus ökonomischer und rechtlicher Perspektive theoretisch analysiert und hieraus Verbesserungsvorschläge ableitet, die anschließend durch eine explorativ-empirische Expertenbefragung abgesichert und ergänzt werden. Konkret beantwortet die Arbeit folgende zentrale Forschungsfrage: „Was ist betrügerisches Verhalten bei geschlossenen Fonds und warum ist dies zum Teil sanktionslos?“ sowie vier ergänzende Forschungsfragen: (1) „Wie sieht die Anatomie betrügerischer geschlossener Fonds aus?“ (2) „Was sind die Ursachen und Anreizstrukturen, die betrügerisches Verhalten bei geschlossenen Fonds begünstigen?“ (3) „Welche Maßnahmen eignen sich zur Abwehr bzw. zur Eindämmung des betrügerischen Verhaltens bei geschlossenen Fonds?“ (4) „Bieten die zivil-, straf- und öffentlich-rechtlichen Maßnahmen des Gesetzgebers, insbesondere das KAGB einen ausreichenden Schutz vor betrügerischen geschlossenen Fonds?“ / Fraudulent behavior in closed-end funds is, according to statistics, responsible for annual capital losses in the mid-triple-digit millions. Legislators have repeatedly addressed the problem in the past and initiated a large number of civil, criminal and public-law measures to improve investor protection, which reached their peak in 2013 with the entry into force of the so-called “Kapitalanlagegesetzbuch” (KAGB). The usefulness of these measures are doubted by critics, moreover it appears that a new phenomenon of 'unsanctioned fraud' on the capital market appears to be established recently, where the perpetrators succeed either without or without significant sanctions, especially in criminal matters. Examples include the Debi Select funds from Landshut and the POC funds from Berlin, in which the 'stripping pullers' operating in the background could be held accountable neither in civil nor in criminal law despite millions in damage to investors. The present work is devoted to the systematic investigation of this phenomenon by theoretically analyzing the topics '(non-sanctioned) fraudulent closed-end funds' and 'investor protection' from an economic and legal perspective and deriving recommendations for improvement, which are then confirmed and supplemented by an explorative-empirical expert survey become. Specifically, the paper answers the following central research question: 'What is fraudulent behavior in closed-end funds and why is this partially sanctionless?' And four complementary research questions: (1) 'What is the anatomy of fraudulent closed-end funds?' (2) 'What are the causes and incentive structures that favor fraudulent behavior in closed-end funds? (3)'What measures are appropriate for the prevention or the containment of fraudulent behavior in closed-end funds?' (4) 'Do civil, criminal and public legislative measures, in particular the KAGB, provide sufficient protection against fraudulent closed-end funds?'