Levenshtein distance is well known for its use in comparing two strings for similarity. However, the set of considered edit operations used when comparing can be reduced in a number of situations. In such cases, the application of the generic Levenshtein distance can result in degraded detection and computational performance. Other metrics in the literature enable limiting the considered edit operations to a smaller subset. However, the possibility where a difference can only result from deleted bytes is not yet explored. To this end, we propose an insert-only variation of the Levenshtein distance to enable comparison of two strings for the case in which differences occur only because of missing bytes. The proposed distance metric is named slice distance and is formally presented and its computational complexity is discussed. We also provide a discussion of the potential security applications of the slice distance.

Firewalls are network security components that handle incoming and outgoing network traffic based on a set of rules. The process of correctly configuring a firewall is complicated and prone to error, and it worsens as the network complexity grows. A poorly configured firewall may result in major security threats; in the case of a network firewall, an organization’s security could be endangered, and in the case of a personal firewall, an individual computer’s security is threatened. A major reason for poorly configured firewalls, as pointed out in the literature, is usability issues. Our aim is to identify existing solutions that help professional and non-professional users to create and manage firewall configuration files, and to analyze the proposals in respect of usability. A systematic literature review with a focus on the usability of firewall configuration is presented in the article. Its main goal is to explore what has already been done in this field. In the primary selection procedure, 1,202 articles were retrieved and then screened. The secondary selection led us to 35 articles carefully chosen for further investigation, of which 14 articles were selected and summarized. As main contributions, we propose a taxonomy of existing solutions as well as a synthesis and in-depth discussion about the state of the art in firewall usability. Among the main findings, we perceived that there is a lack (or even an absence) of usability evaluation or user studies to validate the proposed models. Although all articles are related to the topic of usability, none of them clearly defines it, and only a few actually employ usability design principles and/or guidelines.

Arguably, one of the default solutions to many of today’s everyday errands is to install an app. In order to deliver a variety of convenient and user-centric services, apps need to access different types of information stored in mobile devices, much of which is personal information. In principle, access to such privacy sensitive data should be kept to a minimum. In this study, we focus on privilege utilization patterns by apps installed on Android devices. Though explicit consent is required prior to first time access to the resource, the unavailability of usage information makes it unclear when trying to reassess the users initial decision. On the other hand, if granted privilege with little or no usage, it would suggest the likely violation of the principle of least privilege. Our findings illustrate a plausible requirement for visualising resource usage to aid the user in their decision- making and finer access control mechanisms. 

Firewalls are network security components that allow administrators to handle incoming and outgoing traffic based on a set of rules. Such security appliances are typically the first line of defense, creating a barrier between organization’s internal network and the outside network (e.g., Internet). The process of correctly configuring a firewall is complex and error prone, and it only gets worse as the complexity of the network grows. A vulnerable firewall configuration will very likely result in major threats to the organization’s security. In this report we aim to investigate how to make administrator task of planning and implementing firewall solutions easier, from the stand points of usability and visualization. Our scientific investigation starts with the understanding of the state-of-the-art on this specific field. To do so, we conducted a Systematic Literature Review (SLR), a strict methodology to plan a literature review, to gather relevant information, to synthesize and compare approaches, and to report findings. During the initial search process thousands of papers were screened, leading us to 125 papers carefully selected for further readings. In the secondary study, ten relevant works were identified and assessed, in which authors tackled the issues of usability and visualization for Firewalls and Personal Firewalls. Among the main findings, we perceive that there is a lack (or even absence) of user studies to validate the proposed models. This leads us to a series of unwarranted solutions, that need to be prototyped and tested with real users. We also see an huge opportunity for integrative approaches, that could combine firewall research areas, such as automatic anomaly detection, advisory systems, and varying visualization schemes.

Signature-based intrusion detection systems (IDSs) are commonly utilized in enterprise networks to detect and possibly block a wide variety of attacks. Their application in industrial control systems (ICSs) is also growing rapidly as modem ICSs increasingly use open standard protocols instead of proprietary. Due to an ever changing threat landscape, the rulesets used by these IDSs have grown large and there is no way to verify their precision or accuracy. Such broad and non-optimized rulesets lead to false positives and an unnecessary burden on the IDS, resulting in possible degradation of the security. This work proposes a methodology consisting of a set of tools to help optimize the IDS rulesets and make rule management easier. The work also provides attack traffic data that is expected to benefit the task of IDS assessment.

Today's computer logs are like smoking guns and treasure maps in case of suspicious system activities: they document intrusions, and log crucial information such as failed system updates and crashed services. An adversary thus has a clear motive to observe, alter, and delete log entries, considering that she could (i) start by using the log's content to identify new security vulnerabilities, and (ii) exploit them without ever being detected. With this in mind we consider syslog standards and open source projects that safeguard events during the storage and transit phases, and examine how data compression effects security. We conclude that there are syslog standards in place that satisfy security on a hop-by-hop basis, that there are no such standards for secure storage, and that message compression is not recommended during transit.

Multipath TCP (MPTCP) is an extension to traditionalTCP that enables a number of performance advantages,which were not offered before. While the protocol specificationis close to being finalized, there still remain some concernsregarding deployability and security. This paper describes theon going work to develop a solution that will facilitate thedeployment of MPTCP. The solution will not only allow non-MPTCP capable end-hosts to benefit from MPTCP performancegains, but also help ease the network security concerns that manymiddleboxes face due to the possibility of data stream beingfragmented across multiple subflows.

As technology becomes ubiquitous, new vulnerabilities are being discovered at a rapid rate. Security experts continuously find ways to detect attempts to exploit those vulnerabilities. The outcome is an extremely large and complex rule set used by Intrusion Detection Systems (IDSs) to detect and prevent the vulnerabilities. The rule sets have become so large that it seems infeasible to verify their precision or identify overlapping rules. This work proposes a methodology consisting of a set of tools that will make rule management easier.

The existing network security infrastructure is not ready for future protocols such as Multipath TCP (MPTCP). The outcome is that middleboxes are configured to block such protocols. This paper studies the security risk that arises if future protocols are used over unaware infrastructures. In particular, the practicality and severity of cross-path fragmentation attacks utilizing MPTCP against the signature-matching capability of the Snort intrusion detection system (IDS) is investigated. Results reveal that the attack is realistic and opens the possibility to evade any signature-based IDS. To mitigate the attack, a solution is also proposed in the form of the MPTCP Linker tool. The work outlines the importance of MPTCP support in future network security middleboxes.