DNSSEC -- authenticated denial of existence : understanding zone enumeration

Over the years DNS has proved to be an integral part of the internet infracstructure. For our purposes, DNS is simply a large scale distributed database that maps human-readable domain names to network recognizable IP addresses. Unfortunately, authenticity of responses was not integral to the initial DNS design. This lead to the possibility of a very practical forgery of responses as displayed by Kaminsky's cache poisoning attacks. DNSSEC is primarily designed as a security extension of DNS, that guarantees authenticity of DNS responses. To answer invalid queries in an authenticated manner, DNSSEC initially employed the NSEC records. To its credit, NSEC allowed nameservers to precompute signatures for such negative responses offline. As a result, NSEC is highly scalable while preserving the authenticity/correctness of responses. But, while doing so, NSEC leaks domains from nameserver's zone. This is called zone enumeration. To counter zone enumeration, NSEC3 was deployed. It is a hashed authenticated denial of existence of mechanism,i.e., it reveals the hashes of the zones in a domain. NSEC3 yet allows offline signatures, and is scalable like NSEC. Unfortunately, hashes are vulnerable to dictionary attacks a property exploited by conventional NSEC3 zone enumeration tool, e.g., nsec3walkertool. This leads us to investigate the possibility of constructing an authenticated denial of existence of mechanism which yet allows offline cryptography. To do so, we first define the security goals of a "secure" DNSSEC mechanism in terms of an Authenticated Database System (ADS) with additional goals of privacy, that we define. Any protocol that achieves these goals, maintains the integrity of DNSSEC responses and prevents zone enumeration. We then show that any protocol that achieves such security goals, can be used to construct weak signatures that prevent selective forgeries. This construction, though a strong indication, doesn't confirm the impossibility of generating proofs offline. To confirm that such proofs aren't possible offline, we show attacks of zone enumeration on two large classes of proofs. The provers/responders in this case either repeat proofs non-negligibly often or select proofs as subsets from a pre-computed set of proof elements. The attackers we present use a dictionary of all elements that are likely to occur in the database/zone. The attackers prune the said dictionary to obtain the set of all elements in the database (along with a few additional elements that are erroneously classified to be in the database). These attackers minimize the number of queries made to such responders and are loosely based on the paradigm of Probably Approximately Correct learning as introduced by Valiant

Deploying DNSSEC in islands of security

The Domain Name System (DNS), a name resolution protocol is one of the vulnerable network protocols that has been subjected to many security attacks such as cache poisoning, denial of service and the 'Kaminsky' spoofing attack. When DNS was designed, security was not incorporated into its design. The DNS Security Extensions (DNSSEC) provides security to the name resolution process by using public key cryptosystems. Although DNSSEC has backward compatibility with unsecured zones, it only offers security to clients when communicating with security aware zones. Widespread deployment of DNSSEC is therefore necessary to secure the name resolution process and provide security to the Internet. Only a few Top Level Domains (TLD's) have deployed DNSSEC, this inherently makes it difficult for their sub-domains to implement the security extensions to the DNS. This study analyses mechanisms that can be used by domains in islands of security to deploy DNSSEC so that the name resolution process can be secured in two specific cases where either the TLD is not signed or the domain registrar is not able to support signed domains. The DNS client side mechanisms evaluated in this study include web browser plug-ins, local validating resolvers and domain look-aside validation. The results of the study show that web browser plug-ins cannot work on their own without local validating resolvers. The web browser validators, however, proved to be useful in indicating to the user whether a domain has been validated or not. Local resolvers present a more secure option for Internet users who cannot trust the communication channel between their stub resolvers and remote name servers. However, they do not provide a way of showing the user whether a domain name has been correctly validated or not. Based on the results of the tests conducted, it is recommended that local validators be used with browser validators for visibility and improved security. On the DNS server side, Domain Look-aside Validation (DLV) presents a viable alternative for organizations in islands of security like most countries in Africa where only two country code Top Level Domains (ccTLD) have deployed DNSSEC. This research recommends use of DLV by corporates to provide DNS security to both internal and external users accessing their web based services.LaTeX with hyperref packagepdfTeX-1.40.1

How to Measure TLS, X.509 Certificates, and Web PKI: A Tutorial and Brief Survey

Transport Layer Security (TLS) is the base for many Internet applications and services to achieve end-to-end security. In this paper, we provide guidance on how to measure TLS deployments, including X.509 certificates and Web PKI. We introduce common data sources and tools, and systematically describe necessary steps to conduct sound measurements and data analysis. By surveying prior TLS measurement studies we find that diverging results are rather rooted in different setups instead of different deployments. To improve the situation, we identify common pitfalls and introduce a framework to describe TLS and Web PKI measurements. Where necessary, our insights are bolstered by a data-driven approach, in which we complement arguments by additional measurements

The Impact of DNSSEC on the Internet Landscape

In this dissertation we investigate the security deficiencies of the Domain Name System (DNS) and assess the impact of the DNSSEC security extensions. DNS spoofing attacks divert an application to the wrong server, but are also used routinely for blocking access to websites. We provide evidence for systematic DNS spoofing in China and Iran with measurement-based analyses, which allow us to examine the DNS spoofing filters from vantage points outside of the affected networks. Third-parties in other countries can be affected inadvertently by spoofing-based domain filtering, which could be averted with DNSSEC. The security goals of DNSSEC are data integrity and authenticity. A point solution called NSEC3 adds a privacy assertion to DNSSEC, which is supposed to prevent disclosure of the domain namespace as a whole. We present GPU-based attacks on the NSEC3 privacy assertion, which allow efficient recovery of the namespace contents. We demonstrate with active measurements that DNSSEC has found wide adoption after initial hesitation. At server-side, there are more than five million domains signed with DNSSEC. A portion of them is insecure due to insufficient cryptographic key lengths or broken due to maintenance failures. At client-side, we have observed a worldwide increase of DNSSEC validation over the last three years, though not necessarily on the last mile. Deployment of DNSSEC validation on end hosts is impaired by intermediate caching components, which degrade the availability of DNSSEC. However, intermediate caches contribute to the performance and scalability of the Domain Name System, as we show with trace-driven simulations. We suggest that validating end hosts utilize intermediate caches by default but fall back to autonomous name resolution in case of DNSSEC failures.In dieser Dissertation werden die Sicherheitsdefizite des Domain Name Systems (DNS) untersucht und die Auswirkungen der DNSSEC-Sicherheitserweiterungen bewertet. DNS-Spoofing hat den Zweck eine Anwendung zum falschen Server umzuleiten, wird aber auch regelmäßig eingesetzt, um den Zugang zu Websites zu sperren. Durch messbasierte Analysen wird in dieser Arbeit die systematische Durchführung von DNS-Spoofing-Angriffen in China und im Iran belegt, wobei sich die Messpunkte außerhalb der von den Sperrfiltern betroffenen Netzwerke befinden. Es wird gezeigt, dass Dritte in anderen Ländern durch die Spoofing-basierten Sperrfilter unbeabsichtigt beeinträchtigt werden können, was mit DNSSEC verhindert werden kann. Die Sicherheitsziele von DNSSEC sind Datenintegrität und Authentizität. Die NSEC3-Erweiterung sichert zudem die Privatheit des Domainnamensraums, damit die Inhalte eines DNSSEC-Servers nicht in Gänze ausgelesen werden können. In dieser Arbeit werden GPU-basierte Angriffsmethoden auf die von NSEC3 zugesicherte Privatheit vorgestellt, die eine effiziente Wiederherstellung des Domainnamensraums ermöglichen. Ferner wird mit aktiven Messmethoden die Verbreitung von DNSSEC untersucht, die nach anfänglicher Zurückhaltung deutlich zugenommen hat. Auf der Serverseite gibt es mehr als fünf Millionen mit DNSSEC signierte Domainnamen. Ein Teil davon ist aufgrund von unzureichenden kryptographischen Schlüssellängen unsicher, ein weiterer Teil zudem aufgrund von Wartungsfehlern nicht mit DNSSEC erreichbar. Auf der Clientseite ist der Anteil der DNSSEC-Validierung in den letzten drei Jahren weltweit gestiegen. Allerdings ist hierbei offen, ob die Validierung nahe bei den Endgeräten stattfindet, um unvertraute Kommunikationspfade vollständig abzusichern. Der Einsatz von DNSSEC-Validierung auf Endgeräten wird durch zwischengeschaltete DNS-Cache-Komponenten erschwert, da hierdurch die Verfügbarkeit von DNSSEC beeinträchtigt wird. Allerdings tragen zwischengeschaltete Caches zur Performance und Skalierbarkeit des Domain Name Systems bei, wie in dieser Arbeit mit messbasierten Simulationen gezeigt wird. Daher sollten Endgeräte standardmäßig die vorhandene DNS-Infrastruktur nutzen, bei Validierungsfehlern jedoch selbständig die DNSSEC-Zielserver anfragen, um im Cache gespeicherte, fehlerhafte DNS-Antworten zu umgehen

Lowering Legal Barriers to RPKI Adoption

Across the Internet, mistaken and malicious routing announcements impose significant costs on users and network operators. To make routing announcements more reliable and secure, Internet coordination bodies have encouraged network operators to adopt the Resource Public Key Infrastructure (“RPKI”) framework. Despite this encouragement, RPKI’s adoption rates are low, especially in North America.This report presents the results of a year-long investigation into the hypothesis—widespread within the network operator community—that legal issues pose barriers to RPKI adoption and are one cause of the disparities between North America and other regions of the world. On the basis of interviews and analysis of the legal framework governing RPKI, the report evaluates the issues raised by community members and proposes a number of strategies to reduce or circumvent the barriers that are material. The report also describes substantial action taken this year by the American Registry for Internet Numbers (“ARIN”) and other private organizations in light of public dialogue about RPKI

DETERMINING THE INFLUENCE OF THE NETWORK TIME PROTOCOL (NTP) ON THE DOMAIN NAME SERVICE SECURITY EXTENSION (DNSSEC) PROTOCOL

Recent hacking events against Sony Entertainment, Target, Home Depot, and bank Automated Teller Machines (ATMs) fosters a growing perception that the Internet is an insecure environment. While Internet Privacy Concerns (IPCs) continue to grow out of a general concern for personal privacy, the availability of inexpensive Internet-capable mobile devices increases the Internet of Things (IoT), a network of everyday items embedded with the ability to connect and exchange data. Domain Name Services (DNS) has been integral part of the Internet for name resolution since the beginning. Domain Name Services has several documented vulnerabilities; for example, cache poisoning. The solution adopted by the Internet Engineering Task Force (IETF) to strengthen DNS is DNS Security Extensions (DNSSEC). DNS Security Extensions uses support for cryptographically signed name resolution responses. The cryptography used by DNSSEC is the Public Key Infrastructure (PKI). Some researchers have suggested that the time stamp used in the public certificate of the name resolution response influences DNSSEC vulnerability to a Man-in-the-Middle (MiTM) attack. This quantitative study determined the efficacy of using the default relative Unix epoch time stamp versus an absolute time stamp provided by the Network Time Protocol (NTP). Both a two-proportion test and Fisher’s exact test were used on a large sample size to show that there is a statistically significant better performance in security behavior when using NTP absolute time instead of the traditional relative Unix epoch time with DNSSEC

Network Access Control : single computer viewpoint

The purpose of the thesis was to develop an entirely new ideology and technique which is called a client’s NAC (Client’s Network Access Control). The objectives of the thesis were to discover methods how a single computer could make conclusions about the connected network and validate if the network is trusted or not. This is an entirely new ideology, which has not been published on the commercial markets or in academic research. In a nutshell, the philosophy of the Network Access Control is that all devices requesting access to network’s resources are untrusted until they are otherwise proved. The objective was to discover if it is possible to conduct same kind of philosophy to a single computer. A computer does not trust the network before it has done specific validations from the network and depending on the outcome of the validations; network traffic to network is allowed or denied. The discovery in the thesis was that almost every LAN protocol has different kinds of security issues. Usually these threats are blocked in the network’s outer perimeter with firewalls in such a way that the outside of the network cannot exploit these threats. This does not prevent from exploiting these security threats from inside the network. These findings supported the idea of client’s NAC implementation, because if the network is trusted, the devices in the network are also trusted. The goal was to develop methods and techniques how a single computer could execute the conclusion about the connected network. This included developing the basic architecture of the client’s NAC solution and discovering different authentication methods for authenticating the network. These authentication methods were analyzed with security and implementation analysis and based on these analyzes the thesis recommends certain authentication methods for client to authenticate the connected network.Työn tavoitteena oli kehittää uutta ideologiaa ja tekniikoita (client’s NAC), jossa perinteinen verkkolähtöinen näkökulma pääsynhallinnassa suunnataan yksittäiselle tietokoneelle. Tämän kaltaista tutkimusta tai konseptia ei ollut olemassa, joten kyseessä oli aivan uusi tutkimuksen aihe. Kehittämisessä lähtökohtana oli löytää malli, jonka mukaan yksittäinen tietokone pystyy päättelemään, onko verkko, johon se on kytketty, luotettu vai ei. Työssä sovellettiin ja analysointiin eri autentikointivaihtoehtoja, joiden perusteella esitettiin tiettyjä autentikointitekniikoita client’s NAC -sovelluksen toteuttamiseen. Työ osoitti, että yleisimmissä LAN-protokollissa on merkittäviä uhkia ja haavoittuvuuksia. Jos yksittäinen tietokone kykenee päättelemään verkon luottavuuden, näiden uhkien toteutumista voidaan lieventää, sillä luotettava verkko sisältää vain luotettuja laitteita. Tämä vahvisti, että client’s NAC -konseptin avulla voidaan suojautua epäluotettavien laitteiden haitalliselta tietoliikenteeltä. Eri autentikointimallit jaettiin työssä kahteen eri kategoriaan tulevan kohdeympäristön perusteella. Korkean tietoturvallisuuden ympäristöissä tietoturva ja osapuolten luottavuus on tärkein tekijä suunniteltaessa autentikointimalleja, kun taas matalamman tietoturvaluokan ympäristöihin toteutuksen helppous ja käytettävyys ratkaisee valinnassa. Analysointi eri autentikointimallien välillä suoritettiin tietoturva-analyysillä, joka perustui tietoturvaprotokollissa oleviin yleisimpiin haavoittuvuuksiin, ja toteutusanalyysillä, jossa pyrittiin tekemään päätelmiä toteutuksen toimivuudesta ja vaikeudesta. Näiden analyysien perusteella työ esittää eri vaihtoehtoja eri ympäristöihin toteutettavaksi autentikointitavaksi client’s NAC -sovellukseen

ROVER: a DNS-based method to detect and prevent IP hijacks

2013 Fall.Includes bibliographical references.The Border Gateway Protocol (BGP) is critical to the global internet infrastructure. Unfortunately BGP routing was designed with limited regard for security. As a result, IP route hijacking has been observed for more than 16 years. Well known incidents include a 2008 hijack of YouTube, loss of connectivity for Australia in February 2012, and an event that partially crippled Google in November 2012. Concern has been escalating as critical national infrastructure is reliant on a secure foundation for the Internet. Disruptions to military, banking, utilities, industry, and commerce can be catastrophic. In this dissertation we propose ROVER (Route Origin VERification System), a novel and practical solution for detecting and preventing origin and sub-prefix hijacks. ROVER exploits the reverse DNS for storing route origin data and provides a fail-safe, best effort approach to authentication. This approach can be used with a variety of operational models including fully dynamic in-line BGP filtering, periodically updated authenticated route filters, and real-time notifications for network operators. Our thesis is that ROVER systems can be deployed by a small number of institutions in an incremental fashion and still effectively thwart origin and sub-prefix IP hijacking despite non-participation by the majority of Autonomous System owners. We then present research results supporting this statement. We evaluate the effectiveness of ROVER using simulations on an Internet scale topology as well as with tests on real operational systems. Analyses include a study of IP hijack propagation patterns, effectiveness of various deployment models, critical mass requirements, and an examination of ROVER resilience and scalability

Simulated penetration testing and mitigation analysis

Da Unternehmensnetzwerke und Internetdienste stetig komplexer werden, wird es immer schwieriger, installierte Programme, Schwachstellen und Sicherheitsprotokolle zu überblicken. Die Idee hinter simuliertem Penetrationstesten ist es, Informationen über ein Netzwerk in ein formales Modell zu transferiern und darin einen Angreifer zu simulieren. Diesem Modell fügen wir einen Verteidiger hinzu, der mittels eigener Aktionen versucht, die Fähigkeiten des Angreifers zu minimieren. Dieses zwei-Spieler Handlungsplanungsproblem nennen wir Stackelberg planning. Ziel ist es, Administratoren, Penetrationstestern und der Führungsebene dabei zu helfen, die Schwachstellen großer Netzwerke zu identifizieren und kosteneffiziente Gegenmaßnahmen vorzuschlagen. Wir schaffen in dieser Dissertation erstens die formalen und algorithmischen Grundlagen von Stackelberg planning. Indem wir dabei auf klassischen Planungsproblemen aufbauen, können wir von gut erforschten Heuristiken und anderen Techniken zur Analysebeschleunigung, z.B. symbolischer Suche, profitieren. Zweitens entwerfen wir einen Formalismus für Privilegien-Eskalation und demonstrieren die Anwendbarkeit unserer Simulation auf lokale Computernetzwerke. Drittens wenden wir unsere Simulation auf internetweite Szenarien an und untersuchen die Robustheit sowohl der E-Mail-Infrastruktur als auch von Webseiten. Viertens ermöglichen wir mittels webbasierter Benutzeroberflächen den leichten Zugang zu unseren Tools und Analyseergebnissen.As corporate networks and Internet services are becoming increasingly more complex, it is hard to keep an overview over all deployed software, their potential vulnerabilities, and all existing security protocols. Simulated penetration testing was proposed to extend regular penetration testing by transferring gathered information about a network into a formal model and simulate an attacker in this model. Having a formal model of a network enables us to add a defender trying to mitigate the capabilities of the attacker with their own actions. We name this two-player planning task Stackelberg planning. The goal behind this is to help administrators, penetration testing consultants, and the management level at finding weak spots of large computer infrastructure and suggesting cost-effective mitigations to lower the security risk. In this thesis, we first lay the formal and algorithmic foundations for Stackelberg planning tasks. By building it in a classical planning framework, we can benefit from well-studied heuristics, pruning techniques, and other approaches to speed up the search, for example symbolic search. Second, we design a theory for privilege escalation and demonstrate the applicability of our framework to local computer networks. Third, we apply our framework to Internet-wide scenarios by investigating the robustness of both the email infrastructure and the web. Fourth, we make our findings and our toolchain easily accessible via web-based user interfaces