Another Look at TLS Ecosystems in Networked Devices vs. Web Servers

This is an extension to our paper published in Financial Cryptography and Data Security 2017 conference. In this work we carry out a historical analysis of TLS vulnerabilities of devices compared to Alexa-1M web sites between 2016-2018.

In this page, we host the scripts used for our analysis including instructions using them. However, the processed Censys dataset can only be released upon requesting the authors for non-commercial use with the consent of Censys support (


High-speed IPv4 scanners, such as ZMap, now enable rapid and timely collection of TLS certificates and other security-sensitive parameters. Such large datasets led to the development of the Censys search interface, facilitating comprehensive analysis of TLS deployments in the wild. Several recent studies analyzed TLS certificates as deployed in web servers. Beyond public web servers, TLS is deployed in many other Internet-connected devices, at home and enterprise environments, cyber physical systems, and at network backbones. In Apr. 2017, we reported the results of a preliminary analysis based on measurement data of TLS deployments in such devices (e.g., routers, modems, NAS, printers, SCADA, and IoT devices in general) collected in Oct. 2016 using Censys. We also compared certificates and TLS connection parameters from a security perspective, as found in common devices against top Alexa sites. Censys has evolved since then and its data volume has increased with the addition of several new device types. In this paper, we perform a similar but more comprehensive measurement study to assess TLS vulnerabilities in devices, and compare our current results with our 2016 findings, showing how such systems have evolved in the last one and half year. Indeed, there are noticeable improvements in the TLS ecosystem for devices, especially in terms of adoption of TLS itself (from 29.4% in 2016 to 73.7% in 2018) and stronger cryptographic primitives. However, we also note the continuity of significant weaknesses in devices for which immediate remediation is warranted (e.g., the use of known private keys, SSLv3, MD5-RSA, and RC4). We have also contacted the top manufacturers of vulnerable devices to convey our findings. Most of them blamed users for not updating their devices with latest firmware images that apparently would mitigate the reported findings.

Source code

Click here to download the scripts to transform Censys data to an intermediary format and analyze. The instructions to guide the process is also in the compressed archive.

Authors: Nayanamana Samarasinghe and Mohammad Mannan