Efficient and Secure Cross-Realm Client-to-Client Password-Authenticated Key Exchange

[[conferencetype]]國際[[conferencedate]]20120326~20120329[[iscallforpapers]]Y[[conferencelocation]]Fukuoka, Japa

Mitigating Botnet-based DDoS Attacks against Web Servers

Distributed denial-of-service (DDoS) attacks have become wide-spread on the Internet. They continuously target retail merchants, financial companies and government institutions, disrupting the availability of their online resources and causing millions of dollars of financial losses. Software vulnerabilities and proliferation of malware have helped create a class of application-level DDoS attacks using networks of compromised hosts (botnets). In a botnet-based DDoS attack, an attacker orders large numbers of bots to send seemingly regular HTTP and HTTPS requests to a web server, so as to deplete the server's CPU, disk, or memory capacity. Researchers have proposed client authentication mechanisms, such as CAPTCHA puzzles, to distinguish bot traffic from legitimate client activity and discard bot-originated packets. However, CAPTCHA authentication is vulnerable to denial-of-service and artificial intelligence attacks. This dissertation proposes that clients instead use hardware tokens to authenticate in a federated authentication environment. The federated authentication solution must resist both man-in-the-middle and denial-of-service attacks. The proposed system architecture uses the Kerberos protocol to satisfy both requirements. This work proposes novel extensions to Kerberos to make it more suitable for generic web authentication. A server could verify client credentials and blacklist repeated offenders. Traffic from blacklisted clients, however, still traverses the server's network stack and consumes server resources. This work proposes Sentinel, a dedicated front-end network device that intercepts server-bound traffic, verifies authentication credentials and filters blacklisted traffic before it reaches the server. Using a front-end device also allows transparently deploying hardware acceleration using network co-processors. Network co-processors can discard blacklisted traffic at the hardware level before it wastes front-end host resources. We implement the proposed system architecture by integrating existing software applications and libraries. We validate the system implementation by evaluating its performance under DDoS attacks consisting of floods of HTTP and HTTPS requests

Analysis of two pairing-based three-party password authenticated key exchange protocols

Password-Authenticated Key Exchange (PAKE) protocols allow parties to share secret keys in an authentic manner based on an easily memorizable password. Recently, Nam et al. showed that a provably secure three-party password-based authenticated key exchange protocol using Weil pairing by Wen et al. is vulnerable to a man-in-the-middle attack. In doing so, Nam et al. showed the flaws in the proof of Wen et al. and described how to fix the problem so that their attack no longer works. In this paper, we show that both Wen et al. and Nam et al. variants fall to key compromise impersonation by any adversary. Our results underline the fact that although the provable security approach is necessary to designing PAKEs, gaps still exist between what can be proven and what are really secure in practice

Performance Test Suite for MIT Kerberos

Tato práce se zaměřuje na vyvinutí nástrojů pro výkonnostní testování, které umožní otestovat infrastrukturu systému MIT Kerberos, zjistit její výkonnostní charakteristiky a detekovat potenciální problémy. Práce shrnuje teoretické základy protokolu Kerberos a analyzuje potenciální výkonnostní problémy v různých konfiguracích MIT Kerberosu. Dále práce obsahuje popis návrhu a implementace sady nástrojů pro distribuované testování. Pomocí implementovaných nástrojů bylo odhaleno několik výkonnostních problémů, které jsou v práci popsány spolu s návrhem jejich řešení.The aim of this thesis is to develop performance test suite, which will enable to test MIT Kerberos system infrastructure, assess gained performance characteristics and detect potential bottlenecks. This thesis summarizes necessary theoretical background of Kerberos protocol. Potential performance problems are analyzed on different MIT Kerberos configurations. This thesis describes distributed test suite design and implementation. Several performance problems were discovered using this test suite. These problems are described and some solutions are proposed.

Flexible and Scalable Public Key Security for SSH

A standard tool for secure remote access, the SSH protocol uses public-key cryptography to establish an encrypted and integrity-protected channel with a remote server. However, widely-deployed implementations of the protocol are vulnerable to man-in-the-middle attacks, where an adversary substitutes her public key for the server\u27s. This danger particularly threatens a traveling user Bob borrowing a client machine. Imposing a traditional X.509 PKI on all SSH servers and clients is neither flexible nor scalable nor (in the foreseeable future) practical. Requiring extensive work or an SSL server at Bob\u27s site is also not practical for many users. This paper presents our experiences designing and implementing an alternative scheme that solves the public-key security problem in SSH without requiring such an a priori universal trust structure or extensive sysadmin work--although it does require a modified SSH client. (The code is available for public download.

OpenID Connect Client Registration API for Federated Cloud Platforms

Nowadays, information technology is a key driver in our world. Big cloud federations are aiming to increase their computing power and achieve better results while being scalable. This huge IT systems are managed by multiple users having different roles and at the same time, new services deployment automation is needed to be able to cope with the rising need of resources. This flexibility in deployment has created concerns on the security and the main- tainability of these extensive systems. These requisites have led to start CYCLONE platform, a project focused to provide authentication and authorization services towards services running under control of federated unions of users. CYCLONE, at the moment working as a proof of concept, now allows to authenticate and authorize access to users using one-click-deployment applications against their federation’s credentials. However, actual SSO systems require registration of the services against their Identity Providers in order to provide user validation. In this master thesis, we present two the components of CYCLONE. The first one is a service registration for clients of the OpenID Connect Single Sign-On protocol that allows newly deployed services to be registered automatically against CYCLONE’s SSO component, using RedHat’s Keycloak authentication solution. Based on the real world scenarios that defined the CYCLONE platform, we have designed and implemented a solution alternative to the ones provided by Keycloak, and to evaluate it we have compared it to Keycloak’s alternatives. As a result we have created a simple API implementation from where it’s possible to track who is executing this registrations of new clients, in comparison to the anonymous ones provided by other solutions. The second one is a module that allows easy SSH authorization through the use of CYCLONE’s SSO backend as identity provider and that has been evaluated and tested by one of CYCLONE’s use cases