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Abstract Smart DNS (SDNS) services advertise access to geofenced content (typically, video streaming sites such as Netflix or Hulu) that is normally inaccessible unless the client is within a prescribed geographic region. SDNS is simple to use and involves no software installation. Instead, it requires only that users modify their DNS settings to point to an SDNS resolver. The SDNS resolver “smartly” identifies geofenced domains and, in lieu of their proper DNS resolutions, returns IP addresses of proxy servers located within the geofence. These servers then transparently proxy traffic between the users and their intended destinations, allowing for the bypass of these geographic restrictions. This paper presents the first academic study of SDNS services. We identify a number of serious and pervasive privacy vulnerabilities that expose information about the users of these systems. These include architectural weaknesses that enable content providers to identify which requesting clients use SDNS. Worse, we identify flaws in the design of some SDNS services that allow any arbitrary third party to enumerate these services’ users (by IP address), even if said users are currently offline. We present mitigation strategies to these attacks that have been adopted by at least one SDNS provider in response to our findings.
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Behind Closed Doors: A Network Tale of Spoofing, Intrusion, and False DNS Security
Networks not employing destination-side source address validation (DSAV) expose themselves to a class of pernicious attacks which could be easily prevented by filtering inbound traffic purporting to originate from within the network. In this work, we survey the pervasiveness of networks vulnerable to infiltration using spoofed addresses internal to the network. We issue recursive Domain Name System (DNS) queries to a large set of known DNS servers worldwide, using various spoofed-source addresses. We classify roughly half of the 62,000 networks (autonomous systems) we tested as vulnerable to infiltration due to lack of DSAV. As an illustration of the dangers these networks expose themselves to, we demonstrate the ability to fingerprint the operating systems of internal DNS servers. Additionally, we identify nearly 4,000 DNS server instances vulnerable to cache poisoning attacks due to insufficient---and often non-existent---source port randomization, a vulnerability widely publicized 12 years ago.
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- Award ID(s):
- 1925729
- PAR ID:
- 10287038
- Date Published:
- Journal Name:
- IMC '20: Proceedings of the ACM Internet Measurement Conference
- Page Range / eLocation ID:
- 65 to 77
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)Domain name system (DNS) resolves the IP addresses of domain names and is critical for IP networking. Recent denial-of-service (DoS) attacks on the Internet targeted the DNS system (e.g., Dyn), which has the cascading effect of denying the availability of the services and applications relying on the targeted DNS. In view of these attacks, we investigate the DoS on the DNS system and introduce the query-crafting threats where the attacker controls the DNS query payload (the domain name) to maximize the threat impact per query (increasing the communications between the DNS servers and the threat time duration), which is orthogonal to other DoS approaches to increase the attack impact such as flooding and DNS amplification. We model the DNS system using a state diagram and comprehensively analyze the threat space, identifying the threat vectors which include not only the random/invalid domains but also those using the domain name structure to combine valid strings and random strings. Query-crafting DoS threats generate new domain-name payloads for each query and force increased complexity in the DNS query resolution. We test the query-crafting DoS threats by taking empirical measurements on the Internet and show that they amplify the DoS impact on the DNS system (recursive resolver) by involving more communications and taking greater time duration. To defend against such DoS or DDoS threats, we identify the relevant detection features specific to query-crafting threats and evaluate the defense using our prototype in CloudLab.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3419394.3423649
