Biblio

Threats, posed by ransomware, are rapidly increasing, and its cost on both national and global scales is becoming significantly high as evidenced by the recent events. Ransomware carries out an irreversible process, where it encrypts victims' digital assets to seek financial compensations. Adversaries utilize different means to gain initial access to the target machines, such as phishing emails, vulnerable public-facing software, Remote Desktop Protocol (RDP), brute-force attacks, and stolen accounts. To combat these threats of ransomware, this paper aims to help researchers gain a better understanding of ransomware application profiles through static analysis, where we identify a list of suspicious indicators and similarities among 727 active ran-somware samples. We start with generating portable executable (PE) metadata for all the studied samples. With our domain knowledge and exploratory data analysis tasks, we introduce some of the suspicious indicators of the structure of ransomware files. We reduce the dimensionality of the generated dataset by using the Principal Component Analysis (PCA) technique and discover clusters by applying the KMeans algorithm. This motivates us to utilize the one-class classification algorithms on the generated dataset. As a result, the algorithms learn the common data boundary in the structure of our studied ransomware samples, and thereby, we achieve the data-driven similarities. We use the findings to evaluate the trained classifiers with the test samples and observe that the Local Outlier Factor (LoF) performs better on all the selected feature spaces compared to the One-Class SVM and the Isolation Forest algorithms.

Network covert channels are used in various cyberattacks, including disclosure of sensitive information and enabling stealth tunnels for botnet commands. With time and technology, covert channels are becoming more prevalent, complex, and difficult to detect. The current methods for detection are protocol and pattern specific. This requires the investment of significant time and resources into application of various techniques to catch the different types of covert channels. This paper reviews several patterns of network storage covert channels, describes generation of network traffic dataset with covert channels, and proposes a generic, protocol-independent approach for the detection of network storage covert channels using a supervised machine learning technique. The implementation of the proposed generic detection model can lead to a reduction of necessary techniques to prevent covert channel communication in network traffic. The datasets we have generated for experimentation represent storage covert channels in the IP, TCP, and DNS protocols and are available upon request for future research in this area.