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Maciej Korczyński

Publications and source records attributed to Maciej Korczyński.

18 recordsLinked to original sources

INFERMAL: Inferential analysis of maliciously registered domains

Cybercriminals have long depended on domain names for phishing, spam, malware distribution, and botnet operation. To facilitate the malicious activities, they continually register new domain names for exploitation. Previous work revealed an abnormally high concentration of malicious registrations in a handful of domain name registrars and top-level domains (TLDs). Anecdotal evidence suggests that low registration prices attract cybercriminals, implying that higher costs may potentially discourage them. However, no existing study has systematically analyzed the factors driving abuse, leaving a critical gap in understanding how different variables influence malicious registrations. In this report, we carefully distill the inclinations and aversions of malicious actors during the registration of new phishing domain names. We compile a comprehensive list of 73 features encompassing three main latent factors: registration attributes, proactive verification, and reactive security practices. Through a GLM regression analysis, we find that each dollar reduction in registration fees corresponds to a 49% increase in malicious domains. The availability of free services, such as web hosting, drives an 88% surge in phishing activities. Conversely, stringent restrictions cut down abuse by 63%, while registrars providing API access for domain registration or account creation experience a staggering 401% rise in malicious domains. This exploration may assist intermediaries involved in domain registration to develop tailored anti-abuse practices, yet aligning them with their economic incentives.

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Day in the Life of RIPE Atlas: Operational Insights and Applications in Network Measurements

Network measurement platforms are increasingly popular among researchers and operators alike due to their distributed nature, simplifying measuring the remote parts of the Internet. RIPE Atlas boasts over 12.9K vantage points in 178 countries worldwide and serves as a vital tool for analyzing anycast deployment, network latency, and topology, to name a few. Despite generating over a terabyte of measurement results per day, there is limited understanding of the underlying processes. This paper delves into one day in the life of RIPE Atlas, encompassing 50.9K unique measurements and over 1.3 billion results. While most daily measurements are user-defined, it is built-ins and anchor meshes that account for 89% of produced results. We extensively examine how different probes and measurements contribute to the daily operations of RIPE Atlas and consider any bias they may introduce. Furthermore, we demonstrate how existing measurements can be leveraged to investigate censorship, traceroute symmetry, and the usage of reserved address blocks, among others. Finally, we curate a set of recommendations for researchers using the RIPE Atlas platform to foster transparency, reproducibility, and ethics.

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Looking AT the Blue Skies of Bluesky

The pitfalls of centralized social networks, such as Facebook and Twitter/X, have led to concerns about control, transparency, and accountability. Decentralized social networks have emerged as a result with the goal of empowering users. These decentralized approaches come with their own tradeoffs, and therefore multiple architectures exist. In this paper, we conduct the first large-scale analysis of Bluesky, a prominent decentralized microblogging platform. In contrast to alternative approaches (e.g. Mastodon), Bluesky decomposes and opens the key functions of the platform into subcomponents that can be provided by third party stakeholders. We collect a comprehensive dataset covering all the key elements of Bluesky, study user activity and assess the diversity of providers for each sub-components.

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Guardians of DNS Integrity: A Remote Method for Identifying DNSSEC Validators Across the Internet

DNS Security Extensions (DNSSEC) provide the most effective way to fight DNS cache poisoning attacks. Yet, very few DNS resolvers perform DNSSEC validation. Identifying such systems is non-trivial and the existing methods are not suitable for Internet-scale measurements. In this paper, we propose a novel remote technique for identifying DNSSEC-validating resolvers. The proposed method consists of two steps. In the first step, we identify open resolvers by scanning 3.1 billion end hosts and request every non-forwarder to resolve one correct and seven deliberately misconfigured domains. We then build a classifier that discriminates validators from non-validators based on query patterns and DNS response codes. We find that while most open resolvers are DNSSEC-enabled, less than 18% in IPv4 (38% in IPv6) validate received responses. In the second step, we remotely identify closed non-forwarders in networks that do not have inbound Source Address Validation (SAV) in place. Using the classifier built in step one, we identify 37.4% IPv4 (42.9% IPv6) closed DNSSEC validators and cross-validate the results using RIPE Atlas probes. Finally, we show that the discovered (non)-validators actively send requests to DNS root servers, suggesting that we deal with operational recursive resolvers rather than misconfigured machines.

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Don't Get Hijacked: Prevalence, Mitigation, and Impact of Non-Secure DNS Dynamic Updates

DNS dynamic updates represent an inherently vulnerable mechanism deliberately granting the potential for any host to dynamically modify DNS zone files. Consequently, this feature exposes domains to various security risks such as domain hijacking, compromise of domain control validation, and man-in-the-middle attacks. Originally devised without the implementation of authentication mechanisms, non-secure DNS updates were widely adopted in DNS software, subsequently leaving domains susceptible to a novel form of attack termed zone poisoning. In order to gauge the extent of this issue, our analysis encompassed over 353 million domain names, revealing the presence of 381,965 domains that openly accepted unsolicited DNS updates. We then undertook a comprehensive three-phase campaign involving the notification of Computer Security Incident Response Teams (CSIRTs). Following extensive discussions spanning six months, we observed substantial remediation, with nearly 54\% of nameservers and 98% of vulnerable domains addressing the issue. This outcome serves as evidence that engaging with CSIRTs can prove to be an effective approach for reporting security vulnerabilities. Moreover, our notifications had a lasting impact, as evidenced by the sustained low prevalence of vulnerable domains.

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The Cloud Strikes Back: Investigating the Decentralization of IPFS

Interplanetary Filesystem (IPFS) is one of the largest peer-to-peer filesystems in operation. The network is the default storage layer for Web3 and is being presented as a solution to the centralization of the web. In this paper, we present a large-scale, multi-modal measurement study of the IPFS network. We analyze the topology, the traffic, the content providers and the entry points from the classical Internet. Our measurements show significant centralization in the IPFS network and a high share of nodes hosted in the cloud. We also shed light on the main stakeholders in the ecosystem. We discuss key challenges that might disrupt continuing efforts to decentralize the Web and highlight multiple properties that are creating pressures toward centralization.

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The Closed Resolver Project: Measuring the Deployment of Source Address Validation of Inbound Traffic

Source Address Validation (SAV) is a standard aimed at discarding packets with spoofed source IP addresses. The absence of SAV for outgoing traffic has been known as a root cause of Distributed Denial-of-Service (DDoS) attacks and received widespread attention. While less obvious, the absence of inbound filtering enables an attacker to appear as an internal host of a network and may reveal valuable information about the network infrastructure. Inbound IP spoofing may amplify other attack vectors such as DNS cache poisoning or the recently discovered NXNSAttack. In this paper, we present the preliminary results of the Closed Resolver Project that aims at mitigating the problem of inbound IP spoofing. We perform the first Internet-wide active measurement study to enumerate networks that filter or do not filter incoming packets by their source address, for both the IPv4 and IPv6 address spaces. To achieve this, we identify closed and open DNS resolvers that accept spoofed requests coming from the outside of their network. The proposed method provides the most complete picture of inbound SAV deployment by network providers. Our measurements cover over 55 % IPv4 and 27 % IPv6 Autonomous Systems (AS) and reveal that the great majority of them are fully or partially vulnerable to inbound spoofing. By identifying dual-stacked DNS resolvers, we additionally show that inbound filtering is less often deployed for IPv6 than it is for IPv4. Overall, we discover 13.9 K IPv6 open resolvers that can be exploited for amplification DDoS attacks - 13 times more than previous work. Furthermore, we enumerate uncover 4.25 M IPv4 and 103 K IPv6 vulnerable closed resolvers that could only be detected thanks to our spoofing technique, and that pose a significant threat when combined with the NXNSAttack.

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Security Reputation Metrics

Security reputation metrics (aka. security metrics) quantify the security levels of organization (e.g., hosting or Internet access providers) relative to comparable entities. They enable benchmarking and are essential tools for decision and policy-making in security, and may be used to govern and steer responsible parties towards investing in security when economic or other decision-making factors may drive them to do otherwise.

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Source Address Validation

Source address validation (SAV) is a standard formalized in RFC 2827 aimed at discarding packets with spoofed source IP addresses. The absence of SAV has been known as a root cause of reflection distributed denial-of-service (DDoS) attacks. Outbound SAV (oSAV): filtering applied at the network edge to traffic coming from inside the customer network to the outside. Inbound SAV (iSAV): filtering applied at the network edge to traffic coming from the outside to the customer network.

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Study on Domain Name System (DNS) Abuse: Technical Report

A safe and secure Domain Name System (DNS) is of paramount importance for the digital economy and society. Malicious activities on the DNS, generally referred to as "DNS abuse" are frequent and severe problems affecting online security and undermining users' trust in the Internet. The proposed definition of DNS abuse is as follows: Domain Name System (DNS) abuse is any activity that makes use of domain names or the DNS protocol to carry out harmful or illegal activity. DNS abuse exploits the domain name registration process, the domain name resolution process, or other services associated with the domain name (e.g., shared web hosting service). Notably, we distinguish between: maliciously registered domain names: domain name registered with the malicious intent to carry out harmful or illegal activity compromised domain names: domain name registered by bona fide third-party for legitimate purposes, compromised by malicious actors to carry out harmful and illegal activity. DNS abuse disrupts, damages, or otherwise adversely impacts the DNS and the Internet infrastructure, their users or other persons.

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Early Detection of Spam Domains with Passive DNS and SPF

Spam domains are sources of unsolicited mails and one of the primary vehicles for fraud and malicious activities such as phishing campaigns or malware distribution. Spam domain detection is a race: as soon as the spam mails are sent, taking down the domain or blacklisting it is of relative use, as spammers have to register a new domain for their next campaign. To prevent malicious actors from sending mails, we need to detect them as fast as possible and, ideally, even before the campaign is launched. In this paper, using near-real-time passive DNS data from Farsight Security, we monitor the DNS traffic of newly registered domains and the contents of their TXT records, in particular, the configuration of the Sender Policy Framework, an anti-spoofing protocol for domain names and the first line of defense against devastating Business Email Compromise scams. Because spammers and benign domains have different SPF rules and different traffic profiles, we build a new method to detect spam domains using features collected from passive DNS traffic. Using the SPF configuration and the traffic to the TXT records of a domain, we accurately detect a significant proportion of spam domains with a low false positives rate demonstrating its potential in real-world deployments. Our classification scheme can detect spam domains before they send any mail, using only a single DNS query and later on, it can refine its classification by monitoring more traffic to the domain name.

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Don't Forget to Lock the Front Door! Inferring the Deployment of Source Address Validation of Inbound Traffic

This paper concerns the problem of the absence of ingress filtering at the network edge, one of the main causes of important network security issues. Numerous network operators do not deploy the best current practice - Source Address Validation (SAV) that aims at mitigating these issues. We perform the first Internet-wide active measurement study to enumerate networks not filtering incoming packets by their source address. The measurement method consists of identifying closed and open DNS resolvers handling requests coming from the outside of the network with the source address from the range assigned inside the network under the test. The proposed method provides the most complete picture of the inbound SAV deployment state at network providers. We reveal that 32 673 Autonomous Systems (ASes) and 197 641 Border Gateway Protocol (BGP) prefixes are vulnerable to spoofing of inbound traffic. Finally, using the data from the Spoofer project and performing an open resolver scan, we compare the filtering policies in both directions.

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Tranco: A Research-Oriented Top Sites Ranking Hardened Against Manipulation

In order to evaluate the prevalence of security and privacy practices on a representative sample of the Web, researchers rely on website popularity rankings such as the Alexa list. While the validity and representativeness of these rankings are rarely questioned, our findings show the contrary: we show for four main rankings how their inherent properties (similarity, stability, representativeness, responsiveness and benignness) affect their composition and therefore potentially skew the conclusions made in studies. Moreover, we find that it is trivial for an adversary to manipulate the composition of these lists. We are the first to empirically validate that the ranks of domains in each of the lists are easily altered, in the case of Alexa through as little as a single HTTP request. This allows adversaries to manipulate rankings on a large scale and insert malicious domains into whitelists or bend the outcome of research studies to their will. To overcome the limitations of such rankings, we propose improvements to reduce the fluctuations in list composition and guarantee better defenses against manipulation. To allow the research community to work with reliable and reproducible rankings, we provide Tranco, an improved ranking that we offer through an online service available at https://tranco-list.eu.

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Herding Vulnerable Cats: A Statistical Approach to Disentangle Joint Responsibility for Web Security in Shared Hosting

Hosting providers play a key role in fighting web compromise, but their ability to prevent abuse is constrained by the security practices of their own customers. {\em Shared} hosting, offers a unique perspective since customers operate under restricted privileges and providers retain more control over configurations. We present the first empirical analysis of the distribution of web security features and software patching practices in shared hosting providers, the influence of providers on these security practices, and their impact on web compromise rates. We construct provider-level features on the global market for shared hosting -- containing 1,259 providers -- by gathering indicators from 442,684 domains. Exploratory factor analysis of 15 indicators identifies four main latent factors that capture security efforts: content security, webmaster security, web infrastructure security and web application security. We confirm, via a fixed-effect regression model, that providers exert significant influence over the latter two factors, which are both related to the software stack in their hosting environment. Finally, by means of GLM regression analysis of these factors on phishing and malware abuse, we show that the four security and software patching factors explain between 10\% and 19\% of the variance in abuse at providers, after controlling for size. For web-application security for instance, we found that when a provider moves from the bottom 10\% to the best-performing 10\%, it would experience 4 times fewer phishing incidents. We show that providers have influence over patch levels--even higher in the stack, where CMSes can run as client-side software--and that this influence is tied to a substantial reduction in abuse levels.

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Rotten Apples or Bad Harvest? What We Are Measuring When We Are Measuring Abuse

Internet security and technology policy research regularly uses technical indicators of abuse in order to identify culprits and to tailor mitigation strategies. As a major obstacle, readily available data are often misaligned with actual information needs. They are subject to measurement errors relating to observation, aggregation, attribution, and various sources of heterogeneity. More precise indicators such as size estimates are costly to measure at Internet scale. We address these issues for the case of hosting providers with a statistical model of the abuse data generation process, using phishing sites in hosting networks as a case study. We decompose error sources and then estimate key parameters of the model, controlling for heterogeneity in size and business model. We find that 84\,\% of the variation in abuse counts across 45,358 hosting providers can be explained with structural factors alone. Informed by the fitted model, we systematically select and enrich a subset of 105 homogeneous "statistical twins" with additional explanatory variables, unreasonable to collect for \emph{all} hosting providers. We find that abuse is positively associated with the popularity of websites hosted and with the prevalence of popular content management systems. Moreover, hosting providers who charge higher prices (after controlling for level differences between countries) witness less abuse. These factors together explain a further 77\,\% of the remaining variation, calling into question premature inferences from raw abuse indicators on security efforts of actors, and suggesting the adoption of similar analysis frameworks in all domains where network measurement aims at informing technology policy.

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Developing Security Reputation Metrics for Hosting Providers

Research into cybercrime often points to concentrations of abuse at certain hosting providers. The implication is that these providers are worse in terms of security; some are considered `bad' or even `bullet proof'. Remarkably little work exists on systematically comparing the security performance of providers. Existing metrics typically count instances of abuse and sometimes normalize these counts by taking into account the advertised address space of the provider. None of these attempts have worked through the serious methodological challenges that plague metric design. In this paper we present a systematic approach for metrics development and identify the main challenges: (i) identification of providers, (ii) abuse data coverage and quality, (iii) normalization, (iv) aggregation and (v) metric interpretation. We describe a pragmatic approach to deal with these challenges. In the process, we answer an urgent question posed to us by the Dutch police: `which are the worst providers in our jurisdiction?'. Notwithstanding their limitations, there is a clear need for security metrics for hosting providers in the fight against cybercrime.

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Evaluating the Impact of AbuseHUB on Botnet Mitigation

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.

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No domain left behind: is Let's Encrypt democratizing encryption?

The 2013 National Security Agency revelations of pervasive monitoring have lead 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, the most of web traffic nowadays is 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 established encrypted connections. To address these issues, the Electronic Frontier Foundation, Mozilla Foundation, and the University of Michigan 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.

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