Search

Deduplication of encrypted data is a significant function for both the privacy of stored data and efficient storage management. Several deduplication techniques have been designed to provide improved security or efficiency. In this study, we focus on the client-side deduplication technique, which has more advantages than the server-side deduplication technique, particularly in communication overhead, owing to conditional data transmissions. From a security perspective, poison, dictionary, and identification attacks are considered as threats against client-side deduplication. Unfortunately, in contrast to other attacks, identification attacks and the corresponding countermeasures have not been studied in depth. In identification attacks, an adversary tries to identify the existence of a specific file. Identification attacks should be countered because adversaries can use the attacks to break the privacy of the data owner. Therefore, in the literature, some counter-based countermeasures have been proposed as temporary remedies for such attacks. In this paper, we present an analysis of the security features of deduplication techniques against identification attacks and show that the lack of security of the techniques can be eliminated by providing uncertainness to the conditional responses in the deduplication protocol, which are based on the existence of files. We also present a concrete countermeasure, called the time-locked deduplication technique, which can provide uncertainness to the conditional responses by withholding the operation of the deduplication functionality until a predefined time. An additional cost for locking is incurred only when the file to be stored does not already exist in the server's storage. Therefore, our technique can improve the security of client-side deduplication against identification attacks at almost the same cost as existing techniques, except in the case of files uploaded for the first time. [ABSTRACT FROM AUTHOR]

Research on various security technologies has been actively underway to protect systems from attackers. However, attackers can secure enough time to reconnoiter and attack the target system owing to its static nature. This develops asymmetric warfare in which attackers outwit defenders. Moving target defense (MTD) technologies, which obfuscate the attack surface by modifying the main properties of the potential target system, have been gaining attention as an active cyber security technology. Particularly, network-based MTD (NMTD) technologies, which dynamically mutate the network configuration information, such as IP and ports of the potential target system, can dramatically increase the time required for an attacker to analyze the system. Therefore, this system defense technology has been actively researched. However, increasing the analysis complexity of the target system is limited in conventional NMTD because the variation of system properties (e.g., IP, port) that can be mutated is restricted by the system configuration environment. Therefore, there is a need for an MTD technique that effectively delays an attacker during the system analysis by increasing the variation of system properties. Additionally, in terms of practicality, minimizing the computational overhead arising by the MTD technology and solving the compatibility problem with existing communication protocols are critical issues that cannot be overlooked. In this study, we propose a technology called Ghost-MTD (gMTD). gMTD allows only the user who is aware of protocol mutation patterns to correctly communicate with the service modules of the server system through protocol mutation using the pre-shared one-time bit sequence. Otherwise, gMTD deceives the attackers who attempt to infiltrate the system by redirecting their messages to a decoy-hole module. The experimental results show that the proposed technology enables protocol mutation and validation with a very low performance overhead of only 3.28% to 4.97% using an m-bit (m ≥ 4) length one-time bit sequence and can be applied to real systems regardless of the specific communication protocols. [ABSTRACT FROM AUTHOR]

Nowadays, various computing services are often hosted on cloud platforms for their availability and cost effectiveness. However, such services are frequently exposed to vulnerabilities. Therefore, many countermeasures have been invented to defend against software hacking. At the same time, more complicated attacking techniques have been created. Among them, code-reuse attacks are still an effective means of abusing software vulnerabilities. Although state-of-the-art address space layout randomization (ASLR) runtime-based solutions provide a robust way to mitigate code-reuse attacks, they have fundamental limitations; for example, the need for system modifications, and the need for recompiling source codes or restarting processes. These limitations are not appropriate for mission-critical services because a seamless operation is very important. In this paper, we propose a novel ASLR technique to provide memory rerandomization without interrupting the process execution. In addition, we describe its implementation and evaluate the results. In summary, our method provides a lightweight and seamless ASLR for critical service applications. [ABSTRACT FROM AUTHOR]