Secure and Proactive DNS

Johns Hopkins University, Baltimore MD

Investigators

Abstract

The Domain Name System (DNS) is a hierarchically distributed database that provides information fundamental to Internet operations, such as translating between human readable host names and Internet Protocol (IP) addresses. Due to the importance of the information served by DNS, there is a strong demand for securing communication within the DNS system. The current (insecure) DNS does not prevent attackers from modifying or injecting DNS messages. Users accessing hosts on the Internet rely on the correct translation of host names to IP addresses by the DNS. A typical attack, referred to as DNS spoofing, allows an attacker to manipulate DNS answers on their way to the users. If an attacker makes changes in the DNS tables of a single server, those changes will propagate across the Internet as a viral infection. Increasingly, DNS is also being used to perform load distribution among replicated servers. For instance, companies such as Akamai have used DNS to provide Web content distribution. Moreover, there is consensus that since DNS is a global and available database, it can be employed as a Public Key Infrastructure (PKI) which would enable e-commerce applications. Securing DNS means providing data origin authentication and integrity protection. Existing proposals for securing DNS are mainly based on public-key cryptography. In this proposal, the researcher describes a new approach based on standard symmetric (or secret-key) cryptographic techniques. The researcher introduces the concept of DNS symmetric certificate that are used to create a trusted path from the DNS root server to a server that is authoritative for a portion of the DNS tree. This strategy is very similar to the one introduced by Davis and Swick and symmetric certificates can be seen as a sort of tickets in the Kerberos system which create a trusted path from the authentication server to the destination server going through the ticket-granting server. DNS symmetric certificate are as manageable as public-key certificates with the exception that they cannot be shared, which is not generally required in the DNS system. The project solution enables a wide range of secure services previously believed impractical or too difficult to manage, such as mutual authentication and key revocation. Moreover, the gain in terms of computational complexity, network traffic, and storage requirements is impressive when compared with public-key cryptography based approaches. The research has clear ideas on how to define a secure DNS system based on symmetric-key cryptography. The researcher proposes to build such a system and make public the prototype implementation. The second part of the proposed research, would focus on a still unresolved problem: A DNS server represents a single point of attack which could easily be compromised. The researcher would like to investigate the possibility to distribute the role of a single DNS server among several servers. The research proposes a proactive DNS system that can survive component failures (whether malicious or not) by combining standard techniques of decentralized storage and dynamic self-maintenance. The researchers approach would allow DNS servers to automatically recover from possible, undetected break-ins and then maintain uninterrupted security. The researchers propose to use the proactive security model, which provides a method for maintaining the overall security of a system even when individual components are repeatedly broken into and controlled by an attacker, as long as not too many servers are compromised at the same time. The approach employed by the proactive security model is to first distribute the cryptographic capabilities among several servers, next have the server periodically engage in a refreshment protocol. Information gathered by an attacker before a refreshment period becomes useless to attack the system in the future. The researcher proposes to define, and build, an architecture that combines decentralized storage system technologies, data redundancy and encoding, and dynamic self-maintenance to create survivable DNS servers based on the proactive security model.