Addressing the challenges of modern DNS:a comprehensive tutorial

The Domain Name System (DNS) plays a crucial role in connecting services and users on the Internet. Since its first specification, DNS has been extended in numerous documents to keep it fit for today’s challenges and demands. And these challenges are many. Revelations of snooping on DNS traffic led to changes to guarantee confidentiality of DNS queries. Attacks to forge DNS traffic led to changes to shore up the integrity of the DNS. Finally, denial-of-service attack on DNS operations have led to new DNS operations architectures. All of these developments make DNS a highly interesting, but also highly challenging research topic. This tutorial – aimed at graduate students and early-career researchers – provides a overview of the modern DNS, its ongoing development and its open challenges. This tutorial has four major contributions. We first provide a comprehensive overview of the DNS protocol. Then, we explain how DNS is deployed in practice. This lays the foundation for the third contribution: a review of the biggest challenges the modern DNS faces today and how they can be addressed. These challenges are (i) protecting the confidentiality and (ii) guaranteeing the integrity of the information provided in the DNS, (iii) ensuring the availability of the DNS infrastructure, and (iv) detecting and preventing attacks that make use of the DNS. Last, we discuss which challenges remain open, pointing the reader towards new research areas

On The Impact of Internet Naming Evolution: Deployment, Performance, and Security Implications

As one of the most critical components of the Internet, the Domain Name System (DNS) provides naming services for Internet users, who rely on DNS to perform the translation between the domain names and network entities before establishing an In- ternet connection. In this dissertation, we present our studies on different aspects of the naming infrastructure in today’s Internet, including DNS itself and the network services based on the naming infrastructure such as Content Delivery Networks (CDNs). We first characterize the evolution and features of the DNS resolution in web ser- vices under the emergence of third-party hosting services and cloud platforms. at the bottom level of the DNS hierarchy, the authoritative DNS servers (ADNSes) maintain the actual mapping records and answer the DNS queries. The increasing use of upstream ADNS services (i.e., third-party ADNS-hosting services) and Infrastructure-as-a-Service (IaaS) clouds facilitates the deployment of web services, and has been fostering the evo- lution of the deployment of ADNS servers. to shed light on this trend, we conduct a large-scale measurement to investigate the ADNS deployment patterns of modern web services and examine the characteristics of different deployment styles, such as perfor- mance, life-cycle of servers, and availability. Furthermore, we specifically focus on the DNS deployment for subdomains hosted in IaaS clouds. Then, we examine a pervasive misuse of DNS names and explore a straightforward solution to mitigate the performance penalty in DNS cache. DNS cache plays a critical role in domain name resolution, providing (1) high scalability at Root and Top-level- domain nameservers with reduced workloads and (2) low response latency to clients when the resource records of the queried domains are cached. However, the pervasive misuses of domain names, e.g., the domain names of “one-time-use” pattern, have negative impact on the effectiveness of DNS caching as the cache has been filled with those entries that are highly unlikely to be retrieved. By leveraging the domain name based features that are explicitly available from a domain name itself, we propose simple policies for improving DNS cache performance and validate their efficacy using real traces. Finally, we investigate the security implications of a fundamental vulnerability in DNS- based CDNs. The success of CDNs relies on the mapping system that leverages the dynamically generated DNS records to distribute a client’s request to a proximal server for achieving optimal content delivery. However, the mapping system is vulnerable to malicious hijacks, as it is very difficult to provide pre-computed DNSSEC signatures for dynamically generated records in CDNs. We illustrate that an adversary can deliberately tamper with the resolvers to hijack CDN’s redirection by injecting crafted but legitimate mappings between end-users and edge servers, while remaining undetectable by exist- ing security practices, which can cause serious threats that nullify the benefits offered by CDNs, such as proximal access, load balancing, and DoS protection. We further demonstrate that DNSSEC is ineffective to address this problem, even with the newly adopted ECDSA that is capable of achieving live signing for dynamically generated DNS records. We then discuss countermeasures against this redirection hijacking

Evaluation of Dnssec in Microsoft Windows and Microsoft Windows Server 2008 R2

The Domain Name System (DNS) provides important name resolution services on the Internet. The DNS has been found to have security flaws which have the potential to undermine the reliability of many Internet-based systems. DNS Security Extensions (DNSSEC) offers a long-term solution these DNS security flaws. However, DNSSEC adoption has been slow because it is challenging to deploy and administer. DNSSEC has also been criticized for not being an end-toend solution. Microsoft included support for DNSSEC in its latest operating systems, Windows Server 2008 R2 and Windows 7. This thesis concluded that DNSSEC features in Windows Server 2008 R2 and Windows 7 are not fully developed and are unlikely to impact DNSSEC adoption rates

Library and Tools for Server-Side DNSSEC Implementation

Tato práce se zabývá analýzou současných open source řešení pro zabezpečení DNS zón pomocí technologie DNSSEC. Na základě provedené rešerše je navržena a implementována nová knihovna pro použití na autoritativních DNS serverech. Cílem knihovny je zachovat výhody stávajících řešení a vyřešit jejich nedostatky. Součástí návrhu je i sada nástrojů pro správu politiky a klíčů. Funkčnost vytvořené knihovny je ukázána na jejím použití v serveru Knot DNS.This thesis deals with currently available open-source solutions for securing DNS zones using the DNSSEC mechanism. Based on the findings, a new DNSSEC library for an authoritative name server is designed and implemented. The aim of the library is to keep the benefits of existing solutions and to eliminate their drawbacks. Also a set of utilities to manage keys and signing policy is proposed. The functionality of the library is demonstrated by it's use in the Knot DNS server.

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

Short Paper: On Deployment of DNS-based Security Enhancements

Although the Domain Name System (DNS) was designed as a naming system, its features have made it appealing to repurpose it for the deployment of novel systems. One important class of such systems are security enhancements, and this work sheds light on their deployment. We show the characteristics of these solutions and measure reliability of DNS in these applications. We investigate the compatibility of these solutions with the Tor network, signal necessary changes, and report on surprising drawbacks in Tor's DNS resolution.Comment: Financial Cryptography and Data Security (FC) 201

Hijacking DNS Subdomains via Subzone Registration: A Case for Signed Zones

We investigate how the widespread absence of signatures in DNS (Domain Name System) delegations, in combination with a common misunderstanding with regards to the DNS specification, has led to insecure deployments of authoritative DNS servers which allow for hijacking of subdomains without the domain owner's consent. This, in turn, enables the attacker to perform effective man-in-the-middle attacks on the victim's online services, including TLS (Transport Layer Security) secured connections, without having to touch the victim's DNS zone or leaving a trace on the machine providing the compromised service, such as the web or mail server. Following the practice of responsible disclosure, we present examples of such insecure deployments and suggest remedies for the problem. Most prominently, DNSSEC (Domain Name System Security Extensions) can be used to turn the problem from an integrity breach into a denial-of-service issue, while more thorough user management resolves the issue completely