The Web SSO Standard OpenID Connect: In-Depth Formal Security Analysis and Security Guidelines

Web-based single sign-on (SSO) services such as Google Sign-In and Log In with Paypal are based on the OpenID Connect protocol. This protocol enables so-called relying parties to delegate user authentication to so-called identity providers. OpenID Connect is one of the newest and most widely deployed single sign-on protocols on the web. Despite its importance, it has not received much attention from security researchers so far, and in particular, has not undergone any rigorous security analysis. In this paper, we carry out the first in-depth security analysis of OpenID Connect. To this end, we use a comprehensive generic model of the web to develop a detailed formal model of OpenID Connect. Based on this model, we then precisely formalize and prove central security properties for OpenID Connect, including authentication, authorization, and session integrity properties. In our modeling of OpenID Connect, we employ security measures in order to avoid attacks on OpenID Connect that have been discovered previously and new attack variants that we document for the first time in this paper. Based on these security measures, we propose security guidelines for implementors of OpenID Connect. Our formal analysis demonstrates that these guidelines are in fact effective and sufficient.Comment: An abridged version appears in CSF 2017. Parts of this work extend the web model presented in arXiv:1411.7210, arXiv:1403.1866, arXiv:1508.01719, and arXiv:1601.0122

Analyzing the BrowserID SSO System with Primary Identity Providers Using an Expressive Model of the Web

BrowserID is a complex, real-world Single Sign-On (SSO) System for web applications recently developed by Mozilla. It employs new HTML5 features (such as web messaging and web storage) and cryptographic assertions to provide decentralized login, with the intent to respect users' privacy. It can operate in a primary and a secondary identity provider mode. While in the primary mode BrowserID runs with arbitrary identity providers (IdPs), in the secondary mode there is one IdP only, namely Mozilla's default IdP. We recently proposed an expressive general model for the web infrastructure and, based on this web model, analyzed the security of the secondary IdP mode of BrowserID. The analysis revealed several severe vulnerabilities. In this paper, we complement our prior work by analyzing the even more complex primary IdP mode of BrowserID. We do not only study authentication properties as before, but also privacy properties. During our analysis we discovered new and practical attacks that do not apply to the secondary mode: an identity injection attack, which violates a central authentication property of SSO systems, and attacks that break an important privacy promise of BrowserID and which do not seem to be fixable without a major redesign of the system. Some of our attacks on privacy make use of a browser side channel that has not gained a lot of attention so far. For the authentication bug, we propose a fix and formally prove in a slight extension of our general web model that the fixed system satisfies all the requirements we consider. This constitutes the most complex formal analysis of a web application based on an expressive model of the web infrastructure so far. As another contribution, we identify and prove important security properties of generic web features in the extended web model to facilitate future analysis efforts of web standards and web applications.Comment: arXiv admin note: substantial text overlap with arXiv:1403.186

An Expressive Model for the Web Infrastructure: Definition and Application to the BrowserID SSO System

The web constitutes a complex infrastructure and as demonstrated by numerous attacks, rigorous analysis of standards and web applications is indispensable. Inspired by successful prior work, in particular the work by Akhawe et al. as well as Bansal et al., in this work we propose a formal model for the web infrastructure. While unlike prior works, which aim at automatic analysis, our model so far is not directly amenable to automation, it is much more comprehensive and accurate with respect to the standards and specifications. As such, it can serve as a solid basis for the analysis of a broad range of standards and applications. As a case study and another important contribution of our work, we use our model to carry out the first rigorous analysis of the BrowserID system (a.k.a. Mozilla Persona), a recently developed complex real-world single sign-on system that employs technologies such as AJAX, cross-document messaging, and HTML5 web storage. Our analysis revealed a number of very critical flaws that could not have been captured in prior models. We propose fixes for the flaws, formally state relevant security properties, and prove that the fixed system in a setting with a so-called secondary identity provider satisfies these security properties in our model. The fixes for the most critical flaws have already been adopted by Mozilla and our findings have been rewarded by the Mozilla Security Bug Bounty Program.Comment: An abridged version appears in S&P 201

Use of a plant-based polysaccharide hemostat for the treatment of sternal bleeding after median sternotomy

Background: In cardiac surgery profuse or persistent sternal bleeding after sternotomy is routinely controlled with bone wax. However, bone wax should be avoided, especially in high-risk patients for nonunion of the sternum and infections. Purpose of this study was to evaluate an alternative technique to control bleeding after medium sternotomy using a plant based absorbable polysaccharide hemostat. Methods: A consecutive series of 38 patients requiring median sternotomy for coronary artery bypass surgery (21 OPCAB, 17 CABG) had sternal bleeding control with the polysaccharide hemostat, STARSIL (R) HEMOSTAT. This hemostat is a hydrophilic powder, which achieves hemostasis after topical application at the surgical wound site. Initially it dehydrates blood rapidly, thus accelerating aggregation of platelets and blood solids. Thereafter, it forms a gelled adhesive matrix, which serves as a mechanical barrier against further bleeding. The polysaccharide is completely resorbed within 48 to 72 hours. Results: Satisfactory control of sternal bleeding was observed in 37 patients (97%). No product-related complications were observed or any other major adverse events in an observation period of 3 months. Conclusion: Polysaccharide hemostats appear to be safe and effective for bleeding control of the sternum

Use of a plant-based polysaccharide hemostat for the treatment of sternal bleeding after median sternotomy

Background: In cardiac surgery profuse or persistent sternal bleeding after sternotomy is routinely controlled with bone wax. However, bone wax should be avoided, especially in high-risk patients for nonunion of the sternum and infections. Purpose of this study was to evaluate an alternative technique to control bleeding after medium sternotomy using a plant based absorbable polysaccharide hemostat. Methods: A consecutive series of 38 patients requiring median sternotomy for coronary artery bypass surgery (21 OPCAB, 17 CABG) had sternal bleeding control with the polysaccharide hemostat, STARSIL (R) HEMOSTAT. This hemostat is a hydrophilic powder, which achieves hemostasis after topical application at the surgical wound site. Initially it dehydrates blood rapidly, thus accelerating aggregation of platelets and blood solids. Thereafter, it forms a gelled adhesive matrix, which serves as a mechanical barrier against further bleeding. The polysaccharide is completely resorbed within 48 to 72 hours. Results: Satisfactory control of sternal bleeding was observed in 37 patients (97%). No product-related complications were observed or any other major adverse events in an observation period of 3 months. Conclusion: Polysaccharide hemostats appear to be safe and effective for bleeding control of the sternum

Advanced Transport Protocols for Wireless and Mobile Ad Hoc Networks

This thesis comprises transport protocols in the following different areas of research: Fast Handover allows mobile IP end-devices to roam between wireless access routers without interruptions while communicating to devices in an infrastructure (e.g., in the Internet). This work optimizes the Fast Handover algorithm and evaluates the performance of the transport protocols UDP and TCP during fast handovers via measurements. The following part of the thesis focuses on vehicular ad hoc networks. The thesis designs and evaluates through simulations a point-to-point transport protocol for vehicular ad hoc networks and an algorithm to facilitate the reliable and efficient distribution of information in a geographically scoped target area. Finally, the thesis evaluates the impact of wireless radio fluctuations on the performance of an Ad Hoc Network. Measurements quantify the wireless radio fluctuations. Based on these results, the thesis develops a simple but realistic radio model that evaluates by means of simulations the impact on the performance of an ad hoc network. As a result, the work provides guidelines for future ad hoc protocol design

Interdisciplinary three-step strategy to treat aortic stenosis and coronary artery disease in a patient with end-stage chronic obstructive pulmonary disease

Background: Valvular aortic stenosis is a common disease in the elderly, often in multimorbid patients. It is often associated with coronary artery disease and peripheral artery disease. In this situation, the risk of conventional open-heart surgery is too high, and other treatment strategies have to be evaluated. Case report: A 79-year-old female patient with severe aortic stenosis, coronary artery disease and end-stage chronic obstructive pulmonary disease suffering from dyspnea at rest and permanently dependent on oxygen was treated in three steps. Firstly, her pulmonary infection was treated with antibiotics for 7 days. Then, the left anterior descending artery was stented (bare-metal stent). In the same session, valvuloplasty of the aortic valve was performed. She was sent to rehabilitation to improve her pulmonary condition and took clopidogrel for 4 weeks. Finally, she underwent transapical aortic valve replacement. She was released to rehabilitation on postoperative day 12. Conclusion: A combination of modern interventional and minimally invasive surgical techniques to treat aortic stenosis and coronary heart disease can be a viable option for multimorbid patients with extremely high risk in conventional open-heart surgery

Solutions for IPv6-based mobility in the EU project MobyDick

Proceedings of the WTC 2002, 18th World Telecommunications Congress, Paris, France, 22 -27 September, 2002.Mobile Internet technology is moving towards a packet-based or, more precisely, IPv6-based network. Current solutions on Mobile IPv6 and other related QoS and AAA matters do not offer the security and quality users have come to take for granted. The EU IST project Moby Dick has taken on the challenge of providing a solution that integrates QoS, mobility and AAA in a heterogeneous access environment. This paper focuses on the mobility part of the project, describes and justifies the handover approach taken, shows how QoS-aware and secure handover is achieved, and introduces the project's paging concept. It shows that a transition to a fully integrated IP-RAN and IP-Backbone has become a distinct option for the future.Publicad