Incident handling, a fundamental activity of a cybersecurity incident response team, is a complex discipline that consumes a significant amount of personnel’s time and costs. There are continuous efforts to facilitate incident handling and response in terms of providing procedural or decision support and processing relevant data. In this paper, we survey the approaches towards (semi-)automated incident handling and response backed by recommender systems that are successful in other domains. We discuss which phases and tiers of incident handling can be automated and to what level while evaluating the maturity of proposed approaches and tools. While we did not find a full-scale recommender system that would guide the user through incident handling and suggest which steps to take, many of them aim at particular problems. The discussed issues are not resolved yet but seem to get the attention of researchers and will likely be investigated in the future.

Understanding the information in captured network traffic, extracting the necessary data, and performing incident investigations are principal tasks of network forensics. The analysis of such data is typically performed by tools allowing manual browsing, filtering, and aggregation or tools based on statistical analyses and visualizations facilitating data comprehension. However, the human brain is used to perceiving the data in associations, which these tools can provide only in a limited form. We introduce a GRANEF toolkit that demonstrates a new approach to exploratory network data analysis based on associations stored in a graph database. In this article, we describe data transformation principles, utilization of a scalable graph database, and data analysis techniques. We then discuss and evaluate our proposed approach using a realistic dataset. Although we are at the beginning of our research, the current results show the great potential of association-based analysis.

Adversary thinking is an essential skill for cybersecurity experts, enabling them to understand cyber attacks and set up effective defenses. While this skill is commonly exercised by Capture the Flag games and hands-on activities, we complement these approaches with a key innovation: undergraduate students learn methods of network attack and defense by creating educational games in a cyber range. In this paper, we present the design of two courses, instruction and assessment techniques, as well as our observations over the last three semesters. The students report they had a unique opportunity to deeply understand the topic and practice their soft skills, as they presented their results at a faculty open day event. Their peers, who played the created games, rated the quality and educational value of the games overwhelmingly positively. Moreover, the open day raised awareness about cybersecurity and research and development in this field at our faculty. We believe that sharing our teaching experience will be valuable for instructors planning to introduce active learning of cybersecurity and adversary thinking.

In this paper, we present a framework for graph-based representation of relation between sensors and alert types in a security alert sharing platform. Nodes in a graph represent either sensors or alert types, while edges represent various relations between them, such as common type of reported alerts or duplicated alerts. The graph is automatically updated, stored in a graph database, and visualized. The resulting graph will be used by network administrators and security analysts as a visual guide and situational awareness tool in a complex environment of security alert sharing.

The exchange of security alerts is a current trend in network security and incident response. Alerts from network intrusion detection systems are shared among organizations so that it is possible to see the “big picture” of current security situation. However, the quality and redundancy of the input data seem to be underrated. We present four use cases of aggregation of the alerts from network intrusion detection systems. Alerts from a sharing platform deployed in the Czech national research and education network were examined in a case study. Volumes of raw and aggregated data are presented and a rule of thumb is proposed: up to 85% of alerts can be aggregated. Finally, we discuss the practical implications of alert aggregation for the network intrusion detection system, such as (in)completeness of the alerts and optimal time windows for aggregation.

In this paper, we present a framework for the real-time generation of network traffic statistics on Apache Spark Streaming, a modern distributed stream processing system. Our previous results showed that stream processing systems provide enough throughput to process a large volume of NetFlow data and hence they are suitable for network traffic monitoring. This paper describes the integration of Apache Spark Streaming into a current network monitoring architecture. We prove that it is possible to implement the same basic methods for NetFlow data analysis in the stream processing framework as in the traditional ones. Moreover, our stream processing implementation discovers new information which is not available when using traditional network monitoring approaches.

Modern distributed stream processing systems can potentially be applied to real time network flow processing. However, differences in performance make some systems more suitable than others for being applied to this domain. We propose a novel performance benchmark, which is based on common security analysis algorithms of NetFlow data to determine the suitability of distributed stream processing systems. Three of the most used distributed stream processing systems are bench-marked and the results are compared with NetFlow data processing challenges and requirements. The benchmark results show that each system reached a sufficient data processing speed using a basic deployment scenario with little to no configuration tuning. Our benchmark, unlike any other, enables the performance of small structured messages to be processed on any stream processing system.

The encryption of network traffic complicates legitimate network monitoring, traffic analysis, and network forensics. In this paper, we present real-time lightweight identification of HTTPS clients based on network monitoring and SSL/TLS fingerprinting. Our experiment shows that it is possible to estimate the User-Agent of a client in HTTPS communication via the analysis of the SSL/TLS handshake. The fingerprints of SSL/TLS handshakes, including a list of supported cipher suites, differ among clients and correlate to User-Agent values from a HTTP header. We built up a dictionary of SSL/TLS cipher suite lists and HTTP User-Agents and assigned the User-Agents to the observed SSL/TLS connections to identify communicating clients. The dictionary was used to classify live HTTPS network traffic. We were able to retrieve client types from 95.4 % of HTTPS network traffic. Further, we discussed host-based and network-based methods of dictionary retrieval and estimated the quality of the data.

The growing share of encrypted network traffic complicates network traffic analysis and network forensics. In this paper, we present real-time lightweight identification of HTTPS clients based on network monitoring and SSL/TLS fingerprinting. Our experiment shows that it is possible to estimate the User-Agent of a client in HTTPS communication via the analysis of the SSL/TLS handshake. The fingerprints of SSL/TLS handshakes, including a list of supported cipher suites, differ among clients and correlate to User-Agent values from a HTTP header. We built up a dictionary of SSL/TLS cipher suite lists and HTTP User-Agents and assigned the User-Agents to the observed SSL/TLS connections to identify communicating clients. We discuss host-based and network-based methods of dictionary retrieval and estimate the quality of the data. The usability of the proposed method is demonstrated on two case studies of network forensics.