We consider defenses against confidentiality and integrity attacks on data following break-ins, or so-called intrusion resistant storage technologies. We investigate the problem of protecting secret data, assuming an attacker is inside a target network or has compromised a system. We give a definition of the problem area, and propose a solution, VAST, that uses large, structured files to improve the secure storage of valuable or secret data. Each secret has its multiple shares randomly distributed in an extremely large file. Random decoy shares and the lack of usable identification information prevent selective copying or analysis of the file. No single part of the file yields useful information in isolation from the rest. The file's size and structure therefore present an enormous additional hurdle to attackers attempting to transfer, steal or analyze the data. The system also has the remarkable property of healing itself after malicious corruption, thereby preserving both the confidentiality and integrity of the data. Security technologies have traditionally focused on perimeter defenses. By itself, this approach creates what has been called a lobster-model of security, or "a sort of crunchy shell around a soft, chewy center" [Che90]. If an attacker manages to get into the network, it becomes very difficult to detect or prevent further security compromises. This has prompted the development of secure storage techniques that resist against successful attacks. This paper studies the problem of protecting secret data under the assumption that an attacker has already broken through the network perimeter (or is an "insider"). We give a formal definition of the problem, and present one solution called VAST. The key idea is to distribute secret data in an extremely large storage system without exploitable identification information. Our VAST storage system is orthogonal and complimentary to existing data protection techniques, such as encryption, in that it makes attacks much more difficult to succeed. In this paper, we describe the design rationales, data structures and algorithms. We also describe an implementation of such a system, to demonstrate acceptable normal use. Specifically, we make the following contributions: Definition of Secure Storage Problem. We formally describe the problem of secure storage of secrets in Section 3.1. We describe an abstract data type that is a large storage table composed of records. Operations include initialization, insertion and deletion. We also describe security properties that the table and operations must guarantee. This general description of the problem formalizes intrusion resistant systems, and encourages further research into this general problem area.
Dagon et al. REF define the secure storage problem and present techniques for enhancing security of storage.
Protecting Secret Data from Insider Attacks
In Proc. of Ninth International Conference on Financial Cryptography and Data Security
Computer Science