The ability to identify the author responsible for a given software object is critical for many research studies and for enhancing software transparency and accountability. However, as opposed to other application markets like Apple's iOS App Store, attribution in the Android ecosystem is known to be hard. Prior research has leveraged market metadata and signing certificates to identify software authors without questioning the validity and accuracy of these attribution signals. However, Android application (app) authors can, either intentionally or by mistake, hide their true identity due to: (1) the lack of policy enforcement by markets to ensure the accuracy and correctness of the information disclosed by developers in their market profiles during the app release process, and (2) the use of self-signed certificates for signing apps instead of certificates issued by trusted CAs. In this paper, we perform the first empirical analysis of the availability, volatility and overall aptness of publicly available market and app metadata for author attribution in Android markets. To that end, we analyze a dataset of over 2.5 million market entries and apps extracted from five Android markets for over two years. Our results show that widely used attribution signals are often missing from market profiles and that they change over time. We also invalidate the general belief about the validity of signing certificates for author attribution. For instance, we find that apps from different authors share signing certificates due to the proliferation of app building frameworks and software factories. Finally, we introduce the concept of anattribution graphand we apply it to evaluate the validity of existing attribution signals on the Google Play Store. Our results confirm that the lack of control over publicly available signals can confuse automatic attribution processes.

Network traffic that is not preceded by any Domain Name System (DNS) resolutions is referred to as unnamed traffic. Any DNS-based security system is ineffective against malicious content distributed through this traffic. In this paper, we introduce a novel method for identifying unnamed traffic based on the correlation of flows and DNS responses extracted from raw network traces. We describe two challenges that affect the validity of our method, and how to handle them. By applying our method to a one-week trace of network traffic, we illustrate that unnamed traffic is ubiquitous in a university network across nearly all client systems, destination IP addresses, and destination services. We conclude by presenting several open problems that prevent us from blocking unnamed traffic for security reasons.

The current supply of a highly specialized cyber security professionals cannot meet the demands for societies seeking digitization. To close the skill gap, there is a need for introducing students in higher education to cyber security, and to combine theoretical knowledge with practical skills. This paper presents how the cyber security training platform Haaukins, initially developed to increase interest and knowledge of cyber security among high school students, was further developed to support the need for training in higher education. Based on the differences between the existing and new target audiences, a set of design principles were derived which shaped the technical adjustments required to provide a suitable platform - mainly related to dynamic tooling, centralized access to exercises, and scalability of the platform to support courses running over longer periods of time. The implementation of these adjustments has led to a series of teaching sessions in various institutions of higher education, demonstrating the viability for Haaukins for the new target audience.

This paper investigates the potential of using digital certificates for the detection of phishing domains. This i motivated by phishing domains that have started to abuse the (erroneous) trust of the public in browser padloc symbols, and by the large-scale adoption of the Certificate Transparency (CT) framework. This publicl accessible evidence trail of Transport Layer Security (TLS) certificates has made the TLS landscape mor transparent than ever. By comparing samples of phishing, popular benign, and non-popular benign domains we provide insight into the TLS certificates issuance behavior for phishing domains, focusing on the selectio of the certificate authority, the validation level of the certificates, and the phenomenon of certificate sharin among phishing domains. Our results show that phishing domains gravitate to a relatively small selection o certificate authorities, and disproportionally to cPanel, and tend to rely on certificates with a low, and cheap validation level. Additionally, we demonstrate that the vast majority of certificates issued for phishing domain cover more than only phishing domains. These results suggest that a more pro-active role of CAs and puttin more emphasis on certificate revocation can have a crucial impact in the defense against phishing attacks.

Education of IT security can include a tedious and frustrating experience for novice students and organizers. We have sought out to create an education platform that improves upon this experience, through automation, and individualized learning labs. These learning labs hosts are isolated clusters of virtual computer instances, representing real and insecure computer networks. The platform, named Haaukins, improves upon typical accessibility issues of students and cumbersome configuration management for organizers. In order make the platform accessible for other organizations, it has been open sourced.

The domain name system (DNS) is a core Internet infrastructure that translates names to machine-readable information, such as IP addresses. Security flaws in DNS led to a major overhaul, with the introduction of the DNS security (DNSSEC) extensions. DNSSEC adds integrity and authenticity to the DNS using digital signatures. DNSSEC, however, has its own concerns. It suffers from availability problems due to packet fragmentation and is a potent source of distributed denial-of-service attacks. In earlier work, we argued that many issues with DNSSEC stem from the choice of RSA as default signature algorithm. A switch to alternatives based on elliptic curve cryptography (ECC) can resolve these issues. Yet switching to ECC introduces a new problem: ECC signature validation is much slower than RSA validation. Thus, switching DNSSEC to ECC imposes a significant additional burden on DNS resolvers, pushing load toward the edges of the network. Therefore, in this paper, we study the question: will switching DNSSEC to ECC lead to problems for DNS resolvers, or can they handle the extra load? To answer this question, we developed a model that accurately predicts how many signature validations DNS resolvers have to perform. This allows us to calculate the additional CPU load ECC imposes on a resolver. Using real-world measurements from four DNS resolvers and with two open-source DNS implementations, we evaluate future scenarios where DNSSEC is universally deployed. Our results conclusively show that switching DNSSEC to ECC signature schemes does not impose an insurmountable load on DNS resolvers, even in worst case scenarios.