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Main Authors: Pelekoudas, Athanasios P., Bolis, Epameinondas, Lindner, Jasmin, Kyriakidis, Prodromos, Davidsen, Mathias, Hansen, Johannes T. E., Reichkendler, Christian H., Homayoun, Sajad
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.21652
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author Pelekoudas, Athanasios P.
Bolis, Epameinondas
Lindner, Jasmin
Kyriakidis, Prodromos
Davidsen, Mathias
Hansen, Johannes T. E.
Reichkendler, Christian H.
Homayoun, Sajad
author_facet Pelekoudas, Athanasios P.
Bolis, Epameinondas
Lindner, Jasmin
Kyriakidis, Prodromos
Davidsen, Mathias
Hansen, Johannes T. E.
Reichkendler, Christian H.
Homayoun, Sajad
contents Phishing attacks remain a persistent cybersecurity threat, and the widespread adoption of TLS certificates has unintentionally enabled malicious websites to appear trustworthy to users. This study examines whether certificate metadata and domain characteristics can help distinguish phishing domains from benign domains within the Danish .dk namespace. A dataset was constructed by combining registry information from Punktum dk with phishing reports and popularity rankings from external sources. TLS certificate attributes were collected using Netlas, while additional domain-based features were derived from DNS records and lexical analysis of domain names. The analysis compares phishing, popular, and less frequently visited domains across several feature categories, including Certificate Authorities (CAs), validity periods, missing certificate fields, SAN structure, registrant geography, hosting providers, and lexical properties of domain names. The results indicate that several features show observable differences between phishing and highly popular domains. However, phishing domains often resemble less popular domains, resulting in substantial overlap across many characteristics. Consequently, no individual feature provides a reliable standalone indicator of phishing activity within the Danish namespace. The findings suggest that certificate and domain attributes may still contribute to detection when combined, while also highlighting the limitations of relying on individual indicators in isolation. This work provides an empirical overview of phishing-related infrastructure patterns in the Danish .dk ecosystem and offers insights that may inform future phishing detection approaches.
format Preprint
id arxiv_https___arxiv_org_abs_2603_21652
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle TLS Certificate and Domain Feature Analysis of Phishing Domains in the Danish .dk Namespace
Pelekoudas, Athanasios P.
Bolis, Epameinondas
Lindner, Jasmin
Kyriakidis, Prodromos
Davidsen, Mathias
Hansen, Johannes T. E.
Reichkendler, Christian H.
Homayoun, Sajad
Cryptography and Security
Phishing attacks remain a persistent cybersecurity threat, and the widespread adoption of TLS certificates has unintentionally enabled malicious websites to appear trustworthy to users. This study examines whether certificate metadata and domain characteristics can help distinguish phishing domains from benign domains within the Danish .dk namespace. A dataset was constructed by combining registry information from Punktum dk with phishing reports and popularity rankings from external sources. TLS certificate attributes were collected using Netlas, while additional domain-based features were derived from DNS records and lexical analysis of domain names. The analysis compares phishing, popular, and less frequently visited domains across several feature categories, including Certificate Authorities (CAs), validity periods, missing certificate fields, SAN structure, registrant geography, hosting providers, and lexical properties of domain names. The results indicate that several features show observable differences between phishing and highly popular domains. However, phishing domains often resemble less popular domains, resulting in substantial overlap across many characteristics. Consequently, no individual feature provides a reliable standalone indicator of phishing activity within the Danish namespace. The findings suggest that certificate and domain attributes may still contribute to detection when combined, while also highlighting the limitations of relying on individual indicators in isolation. This work provides an empirical overview of phishing-related infrastructure patterns in the Danish .dk ecosystem and offers insights that may inform future phishing detection approaches.
title TLS Certificate and Domain Feature Analysis of Phishing Domains in the Danish .dk Namespace
topic Cryptography and Security
url https://arxiv.org/abs/2603.21652