Time synchronization is of paramount importance on the Internet, with the Network Time Protocol (NTP) serving as the primary synchronization protocol. The NTP Pool, a volunteer-driven initiative launched two decades ago, facilitates connections between clients and NTP servers. Our analysis of root DNS queries reveals that the NTP Pool has consistently been the most popular time service. We further investigate the DNS component (GeoDNS) of the NTP Pool, which is responsible for mapping clients to servers. Our findings indicate that the current algorithm is heavily skewed, leading to the emergence of time monopolies for entire countries. For instance, clients in the US are served by 551 NTP servers, while clients in Cameroon and Nigeria are served by only one and two servers, respectively, out of the 4k+ servers available in the NTP Pool. We examine the underlying assumption behind GeoDNS for these mappings and discover that time servers located far away can still provide accurate clock time information to clients. We have shared our findings with the NTP Pool operators, who acknowledge them and plan to revise their algorithm to enhance security.@en

hishing on the web is a model of social engineering and an attack vector for getting access to sensitive and financial data of individ- uals and corporations. Phishing has been identified as one of the prime cyber threats in recent years. With the goal to effectively identifying and combating phishing as early as possible, we present in this paper a longitudinal analysis of phishing attacks from the vantage point of three country-code top-level domain (ccTLD) reg- istries that manage more than 8 million active domains – namely the Netherlands’ .nl, Ireland’s .ie, and Belgium’s .be. We perform a longitudinal analysis on phishing attacks spanning up to 10 years, based on more than 28 thousand phishing domains. Our results show two major attack strategies: national companies and organi- zations are far more often impersonated using malicious registered domains under their country own ccTLD, which enables better mimicry of the impersonated company. In stark contrast, interna- tional companies are impersonated using whatever domains that can be compromised, reducing overall mimicry but bearing no reg- istration and financial costs. We show that 80% of phishing attacks in the studied ccTLDs employ compromised domain names and that most research works focus on detecting new domain names instead. We find banks, financial institutions, and high-tech giant compa- nies at the top of the most impersonated targets. We also show the impact of ccTLD’s registration and abuse handling policies on preventing and mitigating phishing attacks, and that mitigation is complex and performed at both web and DNS level at different intermediaries. Last, our results provide a unique opportunity for ccTLDs to compare and revisit their own policies and their impacts, with the goal to improve their own mitigation procedures. @en

Phishing on the web is a model of social engineering and an attack vector for getting access to sensitive and financial data of individuals and corporations. Phishing has been identified as one of the prime cyber threats in recent years. With the goal to effectively identifying and combating phishing as early as possible, we present in this paper a longitudinal analysis of phishing attacks from the vantage point of three country-code top-level domain (ccTLD) registries that manage more than 8 million active domains – namely the Netherlands’ .nl, Ireland’s .ie, and Belgium’s .be. We perform a longitudinal analysis on phishing attacks spanning up to 10 years, based on more than 28 thousand phishing domains. Our results show two major attack strategies: national companies and organizations are far more often impersonated using malicious registered domains under their country own ccTLD, which enables better mimicry of the impersonated company. In stark contrast, international companies are impersonated using whatever domains that can be compromised, reducing overall mimicry but bearing no registration and financial costs. We show that 80% of phishing attacks in the studied ccTLDs employ compromised domain names and that most research works focus on detecting new domain names instead. We find banks, financial institutions, and high-tech giant companies at the top of the most impersonated targets. We also show the impact of ccTLD’s registration and abuse handling policies on preventing and mitigating phishing attacks, and that mitigation is complex and performed at both web and DNS level at different intermediaries. Last, our results provide a unique opportunity for ccTLDs to compare and revisit their policies and impacts, with the goal of improving mitigation procedures. @en

DNS is a protocol responsible for translating human-readable domain names into IP addresses. Despite being essential for many Internet services to work properly, it is inherently vulnerable to manipulation. In November 2021, users from Mexico received bogus DNS responses when resolving whatsapp.net. It appeared that a BGP route leak diverged DNS queries to the local instance of the k-root located in China. Those queries, in turn, encountered middleboxes that injected fake DNS responses. In this paper, we analyze that event from the RIPE Atlas point of view and observe that its impact was more significant than initially thought—the Chinese root server instance was reachable from at least 15 countries several months before being reported. We then launch a nine-month longitudinal measurement campaign using RIPE Atlas probes and locate 11 probes outside China reaching the same instance, although this time over IPv6. More broadly, motivated by the November 2021 event, we study the extent of DNS response injection when contacting root servers. While only less than 1% of queries are impacted, they originate from 7% of RIPE Atlas probes in 66 countries. We conclude by discussing several countermeasures that limit the probability of DNS manipulation.@en

Time synchronization is crucial on the Internet, and the Network Time Protocol (NTP) serves as the primary synchronization protocol. The NTP Pool, a volunteer-driven project introduced 20 years ago, connects clients with NTP servers. Our analysis of Root DNS queries reveals the NTP Pool's widespread use as the most popular time service. Despite its popularity, there has been limited scrutiny of how NTP servers are assigned to clients. In this paper, we investigate the NTP Pool's DNS component (GeoDNS), which maps clients to servers, and find that the current algorithm is overly strict, creating unnecessary risks. We have shared our findings with the NTP Pool operators, who acknowledge them and plan to revise their algorithm to enhance security.@en

DNS latency is a concern for many service operators: CDNs exist to reduce service latency to end-users but must rely on global DNS for reachability and load-balancing. Today, DNS latency is monitored by active probing from distributed platforms like RIPE Atlas, with Verfploeter, or with commercial services. While Atlas coverage is wide, its 10k sites see only a fraction of the Internet. In this paper we show that passive observation of TCP handshakes can measure live DNS latency, continuously, providing good coverage of current clients of the service. Estimating RTT from TCP is an old idea, but its application to DNS has not previously been studied carefully. We show that there is sufficient TCP DNS traffic today to provide good operational coverage (particularly of IPv6), and very good temporal coverage (better than existing approaches), enabling near-real time evaluation of DNS latency from real clients. We also show that DNS servers can optionally solicit TCP to broaden coverage. We quantify coverage and show that estimates of DNS latency from TCP is consistent with UDP latency. Our approach finds previously unknown, real problems: DNS polarization is a new problem where a hypergiant sends global traffic to one anycast site rather than taking advantage of the global anycast deployment. Correcting polarization in Google DNS cut its latency from 100 ms to 10 ms; and from Microsoft Azure cut latency from 90 ms to 20 ms. We also show other instances of routing problems that add 100–200 ms latency. Finally, real-time use of our approach for a European country-level domain has helped detect and correct a BGP routing misconfiguration that detoured European traffic to Australia. We have integrated our approach into several open source tools: ENTRADA, our open source data warehouse for DNS, a monitoring tool (Anteater), which has been operational for the last 2 years on a country-level top-level domain, and a DNS anonymization tool in use at a root server since March 2021.

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Logos give a website a familiar feel and promote trust. Scammers take advantage of that by using well-known organizations’ logos on malicious websites. Unsuspecting Internet users see these logos and think they are looking at a government website or legitimate webshop, when it is a phishing site, a counterfeit webshop, or a site set up to spread misinformation. We present the largest logo detection study on websites to date. We analyze 6.2M domain names from the Netherlands ’ country-code top-level domain.nl, in two case studies to detect logo misuse for two organizations: the Dutch national government and Thuiswinkel Waarborg, an organization that issues certified webshop trust marks. We show how we can detect phishing, spear phishing, dormant phishing attacks, and brand misuse. To that end, we developed LogoMotive, an application that crawls domain names, generates screenshots, and detects logos using supervised machine learning. LogoMotive is operational in the.nl registry, and it is generalizable to detect any other logo in any DNS zone to help identify abuse.

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Electronic government (e-gov) enables citizens and residents to digitally interact with their government via the Internet. Underpinning these services is the Internet Domain Name Systems (DNS), which maps e-gov domain names to Internet addresses. Structuring DNS with multiple levels of redundancy that can withstand stress events such as denial-of-service (DoS) attacks is a challenging task. While the operator community has established best practices to this end, adopting them all involves expert knowledge and resources. In this work, we obtain and study a list of e-gov domain names used by four countries (The Netherlands, Sweden, Switzerland, and the United States) and measure the DNS structuring of these domains. We show the adoption of best practices, inter-country differences such as the use of anycast, and provide recommendations to improve DNS service robustness.@en

The Internet Domain Naming System (DNS) is one of the pillars for the Internet and has been the subject of various Distributed Denial-of-Service (DDoS) attacks over the years. As a countermeasure, the DNS infrastructure has been engineered with a series of replication measures, such as relying on multiple authoritative name servers and using IP anycast. Even though these measures have been in place, we have seen that, when servers rely on third-party DNS providers for reliable services, there may be certain levels of infrastructure centralization. In this case, an attack against a DNS target might affect other authoritative DNS servers sharing part of the infrastructure with the intended victim. However, measuring such levels of infrastructure sharing is a daunting task, given that researchers typically do not have access to DNS provider internals. In this paper, we introduce a methodology and associated tool dnstracker that allows measuring, to various degrees, the level of both concentration and shared infrastructure using active DNS measurements. As a case study, we analyze the authoritative name servers of all domains of the Alexa Top 1 Million most visited websites. Our results show that, in some cases, up to 12.000 authoritative name servers share the same underlying infrastructure of a third-party DNS provider. As such, in the event of an attack, those authoritative DNS servers have increased the probability of suffering from collateral damage.

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Luxury goods such as sneakers and bags are in high demand. Many websites offer them at high discounts, which, in many cases, are simply cheap counterfeit versions of the original product. Online shoppers, however, may be unaware they are buying a counterfeit product and end up being scammed and having to deal with financial losses, as has been widely reported by various news outlets. This work presents a multiyear effort of The Netherlands’.nl country-code top-level domain (ccTLD) in detecting and removing counterfeit online shops from the.nl DNS zone. We have developed two detection systems and partnered with registrars and a large credit card issuer, which ultimately led to more than 4,400 counterfeit online shops being taken down.

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Policy makers in regions such as Europe are increasingly concerned about the trustworthiness and sovereignty of the foundations of their digital economy, because it often depends on systems operated or manufactured elsewhere. To help curb this problem, we propose the novel notion of a responsible Internet, which provides higher degrees of trust and sovereignty for critical service providers (e.g., power grids) and all kinds of other users by improving the transparency, accountability, and controllability of the Internet at the network-level. A responsible Internet accomplishes this through two new distributed and decentralized systems. The first is the Network Inspection Plane (NIP), which enables users to request measurement-based descriptions of the chains of network operators (e.g., ISPs and DNS and cloud providers) that handle their data flows or could potentially handle them, including the relationships between them and the properties of these operators. The second is the Network Control Plane (NCP), which allows users to specify how they expect the Internet infrastructure to handle their data (e.g., in terms of the security attributes that they expect chains of network operators to have) based on the insights they gained from the NIP. We discuss research directions and starting points to realize a responsible Internet by combining three currently largely disjoint research areas: large-scale measurements (for the NIP), open source-based programmable networks (for the NCP), and policy making (POL) based on the NIP and driving the NCP. We believe that a responsible Internet is the next stage in the evolution of the Internet and that the concept is useful for clean slate Internet systems as well.

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The Domain Name System (DNS) is thought of as having the simple-sounding task of resolving domains into IP addresses. With its stub resolvers, different layers of recursive resolvers, authoritative nameservers, a multitude of query types, and DNSSEC, the DNS ecosystem is actually quite complex. In this paper, we introduce DNS Observatory: a new stream analytics platform that provides a bird's-eye view on the DNS. As the data source, we leverage a large stream of passive DNS observations produced by hundreds of globally distributed probes, acquiring a peak of 200 k DNS queries per second between recursive resolvers and authoritative nameservers. For each observed DNS transaction, we extract traffic features, aggregate them, and track the top-k DNS objects, e.g., the top authoritative nameserver IP addresses or the top domains. We analyze 1.6 trillion DNS transactions over a four month period. This allows us to characterize DNS deployments and traffic patterns, evaluate its associated infrastructure and performance, as well as gain insight into the modern additions to the DNS and related Internet protocols. We find an alarming concentration of DNS traffic: roughly half of the observed traffic is handled by only 1 k authoritative nameservers and by 10 AS operators. By evaluating the median delay of DNS queries, we find that the top 10 k nameservers have indeed a shorter response time than less popular nameservers, which is correlated with less router hops. We also study how DNS TTL adjustments can impact query volumes, anticipate upcoming changes to DNS infrastructure, and how negative caching TTLs affect the Happy Eyeballs algorithm. We find some popular domains with a a share of up to 90 % of empty DNS responses due to short negative caching TTLs. We propose actionable measures to improve uncovered DNS shortcomings.

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To enhance competition and choice in the domain name system, ICANN introduced the new gTLD program, which added hundreds of new gTLDs (e.g. .nyc, .io) to the root DNS zone. While the program arguably increased the range of domain names available to consumers, it might also have created new opportunities for cybercriminals. To investigate that, we present the first comparative study of abuse in the domains registered under the new gTLD program and legacy gTLDs (18 in total, such as .com, .org). We combine historical datasets from various sources, including DNS zone files, WHOIS records, passive and active DNS and HTTP measurements, and 11 reputable abuse feeds to study abuse across gTLDs. We find that the new gTLDs appear to have diverted abuse from the legacy gTLDs: while the total number of domains abused for spam remains stable across gTLDs, we observe a growing number of spam domains in new gTLDs which suggests a shift from legacy gTLDs to new gTLDs. Although legacy gTLDs had a rate of 56.9 spam domains per 10,000 registrations (Q4 2016), new gTLDs experienced a rate of 526.6 in the same period-which is almost one order of magnitude higher. In this study, we also analyze the relationship between DNS abuse, operator security indicators and the structural properties of new gTLDs. The results indicate that there is an inverse correlation between abuse and stricter registration policies. Our findings suggest that cybercriminals increasingly prefer to register, rather than hack, domain names and some new gTLDs have become a magnet for malicious actors. ICANN is currently using these results to review the existing anti-abuse safeguards, evaluate their joint effects and to introduce more effective safeguards before an upcoming new gTLD rollout.

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The 2013 National Security Agency revelations of pervasive monitoring have led to an "encryption rush" across the computer and Internet industry. To push back against massive surveillance and protect users' privacy, vendors, hosting and cloud providers have widely deployed encryption on their hardware, communication links, and applications. As a consequence, most web connections nowadays are encrypted. However, there is still a significant part of Internet traffic that is not encrypted. It has been argued that both costs and complexity associated with obtaining and deploying X.509 certificates are major barriers for widespread encryption, since these certificates are required to establish encrypted connections. To address these issues, the Electronic Frontier Foundation, Mozilla Foundation, the University of Michigan and a number of partners have set up Let's Encrypt (LE), a certificate authority that provides both free X.509 certificates and software that automates the deployment of these certificates. In this paper, we investigate if LE has been successful in democratizing encryption: we analyze certificate issuance in the first year of LE and show from various perspectives that LE adoption has an upward trend and it is in fact being successful in covering the lower-cost end of the hosting market.@en

This documents presents the final report of a two-year project to evaluate the impact of AbuseHUB, a Dutch clearinghouse for acquiring and processing abuse data on infected machines. The report was commissioned by the Netherlands Ministry of Economic Affairs, a co-funder of the development of AbuseHUB. AbuseHUB is the initiative of 9 Internet Service Providers, SIDN (the registry for the .nl top-level domain) and Surfnet (the national research and education network operator). The key objective of AbuseHUB is to improve the mitigation of botnets by its members. We set out to assess whether this objective is being reached by analyzing malware infection levels in the networks of AbuseHUB members and comparing them to those of other Internet Service Providers (ISPs). Since AbuseHUB members together comprise over 90 percent of the broadband market in the Netherlands, it also makes sense to compare how the country as a whole has performed compared to other countries. This report complements the baseline measurement report produced in December 2013 and the interim report from March 2015. We are using the same data sources as in the interim report, which is an expanded set compared to the earlier baseline report and to our 2011 study into botnet mitigation in the Netherlands.@en