ANALYZING TEMPORAL PATTERNS IN PHISHING EMAIL TOPICS

In 2020, the Federal Bureau of Investigation (FBI) found phishing to be the most common cybercrime, with a record number of complaints from Americans reporting losses exceeding $4.1 billion. Various phishing prevention methods exist; however, these methods are usually reactionary in nature as they activate only after a phishing campaign has been launched. Priming people ahead of time with the knowledge of which phishing topic is more likely to occur could be an effective proactive phishing prevention strategy. It has been noted that the volume of phishing emails tended to increase around key calendar dates and during times of uncertainty. This thesis aimed to create a classifier to predict which phishing topics have an increased likelihood of occurring in reference to an external event. After distilling around 1.2 million phishes until only meaningful words remained, a Latent Dirichlet allocation (LDA) topic model uncovered 90 latent phishing topics. On average, human evaluators agreed with the composition of a topic 74% of the time in one of the phishing topic evaluation tasks, showing an accordance of human judgment to the topics produced by the LDA model. Each topic was turned into a timeseries by creating a frequency count over the dataset’s two-year timespan. This time-series was changed into an intensity count to highlight the days of increased phishing activity. All phishing topics were analyzed and reviewed for influencing events. After the review, ten topics were identified to have external events that could have possibly influenced their respective intensities. After performing the intervention analysis, none of the selected topics were found to correlate with the identified external event. The analysis stopped here, and no predictive classifiers were pursued. With this dataset, temporal patterns coupled with external events were not able to predict the likelihood of a phishing attack

TOPIC MODELING FOR EMAIL SUBJECT LINE ANALYSIS

Email processing is an emerging area in natural language processing and machine learning. Archivists often must make judgements about the relevance and record status of email messages. This study is an attempt to streamline that process by testing subject line and message body analysis using topic modeling. Specifically, using the Enron Corpus and Latent Dirichlet Allocation, this study investigates the extent to which email subject lines can be used to predict the content of email messages to support efficient archival processing.Master of Science in Information Scienc

A unified formal framework for factorial and probabilistic topic modelling

Topic modelling has become a highly popular technique for extracting knowledge from texts. It encompasses various method families, including Factorial methods, Probabilistic methods, and Natural Language Processing methods. This paper introduces a unified conceptual framework for Factorial and Probabilistic methods by identifying shared elements and representing them using a homogeneous notation. The paper presents 12 different methods within this framework, enabling easy comparative analysis to assess the flexibility and how realistic the assumptions of each approach are. This establishes the initial stage of a broader analysis aimed at relating all method families to this common framework, comprehensively understanding their strengths and weaknesses, and establishing general application guidelines. Also, an experimental setup reinforces the convenience of having harmonized notational schema. The paper concludes with a discussion on the presented methods and outlines future research directions.Peer ReviewedPostprint (published version

Document-level sentiment analysis of email data

Sisi Liu investigated machine learning methods for Email document sentiment analysis. She developed a systematic framework that has been qualitatively and quantitatively proved to be effective and efficient in identifying sentiment from massive amount of Email data. Analytical results obtained from the document-level Email sentiment analysis framework are beneficial for better decision making in various business settings

Nonnegative Matrix Factorization for Signal and Data Analytics: Identifiability, Algorithms, and Applications

Nonnegative matrix factorization (NMF) has become a workhorse for signal and data analytics, triggered by its model parsimony and interpretability. Perhaps a bit surprisingly, the understanding to its model identifiability---the major reason behind the interpretability in many applications such as topic mining and hyperspectral imaging---had been rather limited until recent years. Beginning from the 2010s, the identifiability research of NMF has progressed considerably: Many interesting and important results have been discovered by the signal processing (SP) and machine learning (ML) communities. NMF identifiability has a great impact on many aspects in practice, such as ill-posed formulation avoidance and performance-guaranteed algorithm design. On the other hand, there is no tutorial paper that introduces NMF from an identifiability viewpoint. In this paper, we aim at filling this gap by offering a comprehensive and deep tutorial on model identifiability of NMF as well as the connections to algorithms and applications. This tutorial will help researchers and graduate students grasp the essence and insights of NMF, thereby avoiding typical `pitfalls' that are often times due to unidentifiable NMF formulations. This paper will also help practitioners pick/design suitable factorization tools for their own problems.Comment: accepted version, IEEE Signal Processing Magazine; supplementary materials added. Some minor revisions implemente