arXiv subjects

Angelos Stavrou

Publications and source records attributed to Angelos Stavrou.

22 records · Page 2Linked to original sources

arXiv2019

20 Years of DDoS: a Call to Action

Botnet Distributed Denial of Service (DDoS) attacks are now 20 years old; what has changed in that time? Their disruptive presence, their volume, distribution across the globe, and the relative ease of launching them have all been trending in favor of attackers. Our increases in network capacity and our architectural design principles are making our online world richer, but are favoring attackers at least as much as Internet services. The DDoS mitigation techniques have been evolving but they are losing ground to the increasing sophistication and diversification of the attacks that have moved from the network to the application level, and we are operationally falling behind attackers. It is time to ask fundamental questions: are there core design issues in our network architecture that fundamentally enable DDoS attacks? How can our network infrastructure be enhanced to address the principles that enable the DDoS problem? How can we incentivize the development and deployment of the necessary changes? In this article, we want to sound an alarm and issue a call to action to the research community. We propose that basic research and principled analyses are badly needed, because the status quo does not paint a pretty picture for the future.

cs.NI↗

arXiv2018

Moving-target Defense against Botnet Reconnaissance and an Adversarial Coupon-Collection Model

We consider a cloud based multiserver system consisting of a set of replica application servers behind a set of proxy (indirection) servers which interact directly with clients over the Internet. We study a proactive moving-target defense to thwart a DDoS attacker's reconnaissance phase and consequently reduce the attack's impact. The defense is effectively a moving-target (motag) technique in which the proxies dynamically change. The system is evaluated using an AWS prototype of HTTP redirection and by numerical evaluations of an adversarial coupon-collector mathematical model, the latter allowing larger-scale extrapolations.

cs.CR↗

arXiv2017

Numerical Evaluation of Cloud-Side Shuffling Defenses against DDoS Attacks on Proxied Multiserver Systems

We consider a cloud based multiserver system, that may be cloud based, consisting of a set of replica application servers behind a set of proxy (indirection) servers which interact directly with clients over the Internet. We address cloud-side proactive and reactive defenses to combat DDoS attacks that may target this system. DDoS attacks are endemic with some notable attacks occurring just this past fall. Volumetric attacks may target proxies while "low volume" attacks may target replicas. After reviewing existing and proposed defenses, such as changing proxy IP addresses (a "moving target" technique to combat the reconnaissance phase of the botnet) and fission of overloaded servers, we focus on evaluation of defenses based on shuffling client-to-server assignments that can be both proactive and reactive to a DDoS attack. Our evaluations are based on a binomial distribution model that well agrees with simulations and preliminary experiments on a prototype that is also described.

cs.CR↗

arXiv2011

Decryptable to Your Eyes: Visualization of Security Protocols at the User Interface

The design of authentication protocols, for online banking services in particular and any service that is of sensitive nature in general, is quite challenging. Indeed, enforcing security guarantees has overhead thus imposing additional computation and design considerations that do not always meet usability and user requirements. On the other hand, relaxing assumptions and rigorous security design to improve the user experience can lead to security breaches that can harm the users' trust in the system. In this paper, we demonstrate how careful visualization design can enhance not only the security but also the usability of the authentication process. To that end, we propose a family of visualized authentication protocols, a visualized transaction verification, and a "decryptable to your eyes only" protocol. Through rigorous analysis, we verify that our protocols are immune to many of the challenging authentication attacks applicable in the literature. Furthermore, using an extensive case study on a prototype of our protocols, we highlight the potential of our approach for real-world deployment: we were able to achieve a high level of usability while satisfying stringent security requirements.

cs.CR↗