Mitigating Denial-Of-Service Attacks on the Chord Overlay Network:A Location Hiding Approach

Server less distributed computing has received significant attention from both the industry and the research community. Among the most popular applications are the wide-area network file systems, exemplified by CFS, Far site, and Ocean Store. These file systems store files on a large collection of entrusted nodes that form an overlay network. They use cryptographic techniques to maintain file confidentiality and integrity from malicious nodes. Unfortunately, cryptographic techniques cannot protect a file holder from a denial-of-service (DoS) attack or a host compromise attack. Hence, most of these distributed file systems are vulnerable to targeted file attacks, wherein an adversary attempts to attack a small (chosen) set of files by attacking the nodes that host them. This paper presents Location Guard—a location hiding technique for securing overlay file storage systems from targeted file attacks. Location Guard has three essential components: 1) location key, consisting of a random bit string (e.g., 128 bits) that serves as the key to the location of a file, 2) routing guard, a secure algorithm that protects accesses to a file in the overlay network given its location key such that neither its key nor its location is revealed to an adversary, and 3) a set of location inference guards, which refer to an extensible component of the Location Guard. Our experimental results quantify the overhead of employing Location Guard and demonstrate its effectiveness against DoS attacks, host compromise attacks, and various location inference attacks.