Cryptology ePrint Archive: Report 2019/941

Does "www." Mean Better Transport Layer Security?

Eman Salem Alashwali and Pawel Szalachowski and Andrew Martin

Abstract: Experience shows that most researchers and developers tend to treat plain-domains (those that are not prefixed with “www” sub-domains, e.g. “”) as synonyms for their equivalent www-domains (those that are prefixed with “www” sub-domains, e.g. “”). In this paper, we analyse datasets of nearly two million plain-domains against their equivalent www-domains to answer the following question: Do plain-domains and their equivalent www-domains differ in TLS security configurations and certificates? If so, to what extent? Our results provide evidence of an interesting phenomenon: plain-domains and their equivalent www-domains differ in TLS security configurations and certificates in a non-trivial number of cases. Furthermore, www-domains tend to have stronger security configurations than their equivalent plain-domains. Interestingly, this phenomenon is more prevalent in the most-visited domains than in randomly-chosen domains. Further analysis of the top domains dataset shows that 53.35% of the plain-domains that show one or more weakness indicators (e.g. expired certificate) that are not shown in their equivalent www-domains perform HTTPS redirection from HTTPS plain-domains to their equivalent HTTPS www-domains. Additionally, 24.71% of these redirections contains plain-text HTTP intermediate URLs. In these cases, users see the final www-domains with strong TLS configurations and certificates, but in fact, the HTTPS request has passed through plain-domains that have less secure TLS configurations and certificates. Clearly, such a set-up introduces a weak link in the security of the overall interaction.

Category / Keywords: applications / network, internet, security, analysis, protocol, TLS, SSL, measurement, applied cryptography

Original Publication (in the same form): 14th International Conference on Availability, Reliability and Security (ARES 2019)

Date: received 18 Aug 2019

Contact author: eman alashwali at gmail com

Available format(s): PDF | BibTeX Citation

Version: 20190818:160418 (All versions of this report)

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