E-commerce has become a self-evident part of our everyday life over the last few years, and its importance continues to grow. However, the success comes at a price: Not only has the volume of e-commerce transactions grown, but also the volume of fraudulent e-commerce transactions has increased in parallel too, at an even greater rate. Fraudsters are trying hard to emulate legitimate behaviour and behave like genuine customers, which tricks retailers and causes not only financial damage. The thesis at hand is focused on B2C e-commerce fraud. The relevance and impact of e-commerce fraud is highlighted, and indicators for fraudulent e-commerce transactions are determined. Moreover, e-commerce transactions are analysed, and their vulnerabilities and their susceptibility with regard to fraud attempts are investigated and evaluated. Measures to prevent and to detect e-commerce fraud are gathered and analysed as well. Interviews with investigators and experts in this field are conducted to gain practical insights, and to enhance the knowledge and discuss the results acquired from the literature research. Furthermore, legal aspects with regard to e-commerce fraud are examined. This comprises an analysis of the Austrian legislation as well as international endeavours against e-commerce fraud (with an impact on Austrian laws), as e-commerce (and, consequently, e-commerce fraud) is inherently cross-border. Another factor contributes to the rise of e-commerce fraud as well: Over the last few years, cybercriminals have advanced to profit- and service-oriented business models, leading to a phenomenon referred to as Crime-as-a-Service. Cybercriminals provide their goods and services to other criminals, which is why the entry barrier is diminished, making it easier for criminals to commit crimes like e-commerce fraud. An investigative research of the relevance and impact of Crime-as-a-Service on e-commerce fraud and its facilitating role is also included in the present thesis.