Countering Targeted File Attacks Using LocationGuard

Serverless file systems, exemplified by CFS, Farsite and OceanStore, have received significant attention from both the industry and the research community. These file systems store files on a large collection of untrusted 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) 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 LocationGuard a location hiding technique for securing overlay file storage systems from targeted file attacks. LocationGuard has three essential components: (i) location key, consisting of a random bit string (e.g., 128 bits) that serves as the key to the location of a file, (ii) 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 (iii) a set of four location inference guards. Our experimental results quantify the overhead of employing LocationGuard and demonstrate its effectiveness against DoS attacks, host compromise attacks and various location inference attacks.