We analyze the increasing threats against IoT devices. We show that Telnet-based attacks that target IoT devices have rocketed since 2014. Based on this observation, we propose an IoT honeypot and sandbox, which attracts and analyzes Telnet-based attacks against various IoT devices running on different CPU architectures such as ARM, MIPS, and PPC. By analyzing the observation results of our honeypot and captured malware samples, we show that there are currently at least 5 distinct DDoS malware families targeting Telnet-enabled IoT devices and one of the families has quickly evolved to target more devices with as many as 9 different CPU architectures.

As Domain Name System (DNS) provides flexibility and robustness in communications of hosts on Internet, not only legitimate users but also attackers often take advantages of it. If we know how attackers are managing their malicious domains with authoritative name servers, there is a possibility to detect not only malicious domains but also malicious authoritative name servers. In this study, we present a novel method for detecting malicious "domains" (noted as d) and malicious "authoritative name servers" (noted as ns-d) based on their distinct mappings to "IP addresses" (noted as IP). Namely, we present three features to detect them; 1) Single ns-d is mapped to many IP, 2) Single IP is mapped to many ns-d, and 3) Single IP is mapped to both ns-d and d. We evaluate proposed method in terms of accuracy and coverage in detection of malicious d and ns-d. The evaluation shows that our detection method can achieve significantly low false positive rate in detecting both malicious d and ns-d without relying on any previous knowledge, such as blacklists or whitelists.

This study proposes how to investigate the existence of misconfigurations of zone transfer in any level of domain name system hierarchy using search engine based approach without the need to look at the zone file. The analysis has been conducted on 1,284 authoritative name servers of 314 top-level domains and 46,416 authoritative name servers of second level domain of 249 country code top-level domains. In case of top-level domains investigation, 84 name servers authoritative to answer for 53 top-level domains are misconfigured and allow zone transfer to us. In case of second level domains investigation, 5,394 authoritative name servers authoritative to answer for 6,234 second-level domains allow zone transfer. In particular, we found a serious misconfiguration case where the misconfigured DNS server was authoritative for not only its TLD but also SLD and lower level, exposing 83 % the DNS related information of the country to the public.