Commodity operating system (OS) kernels, such as Windows, Mac OS X, Linux, and FreeBSD, are susceptible to numerous security vulnerabilities. Their monolithic design gives successful attackers complete access to all application data and system resources. Shielding systems such as InkTag, Haven, and Virtual Ghost protect sensitive application data from compromised OS kernels. However, such systems are still vulnerable to side-channel attacks. Worse yet, compromised OS kernels can leverage their control over privileged hardware state to exacerbate existing side channels; recent work has shown that a compromised OS kernel can steal entire documents via side channels. This paper presents defenses against page table and last-level cache (LLC) side-channel attacks launched by a compromised OS kernel. Our page table defenses restrict the OS kernel’s ability to read and write page table pages and defend against page allocation attacks, and our LLC defenses utilize the Intel Cache Allocation Technology along with memory isolation primitives. We proto- type our solution in a system we call Apparition, building on an optimized version of Virtual Ghost. Our evaluation shows that our side-channel defenses add 1% to 18% (with up to 86% for one application) overhead to the optimized Virtual Ghost (relative to the native kernel) on real-world applications.
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On Vulnerability of Access Control Restrictions to Timing Attacks in a Database Management System
Side-channel attacks leverage implementation of algorithms to bypass security and leak restricted data. A timing attack observes differences in runtime in response to varying inputs to learn restricted information. Most prior work has focused on applying timing attacks to cryptoanalysis algorithms; other approaches sought to learn about database content by measuring the time of an operation (e.g., index update or query caching). Our goal is to evaluate the practical risks of leveraging a non-privileged user account to learn about data hidden from the user account by access control. As with other side-channel attacks, this attack exploits the inherent nature of how queries are executed in a database system. Internally, the database engine processes the entire database table, even if the user only has access to some of the rows. We present a preliminary investigation of what a regular user can learn about “hidden” data by observing the execution time of their queries over an indexed column in a table. We perform our experiments in a cache-control environment (i.e., clearing database cache between runs) to measure an upper bound for data leakage and privacy risks. Our experiments show that, in a real system, it is difficult to reliably learn about restricted data due to natural operating system (OS) runtime fluctuations and OS-level caching. However, when the access control mechanism itself is relatively costly, a user can not only learn about hidden data but they may closely approximate the number of rows hidden by the access control mechanism.
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- Award ID(s):
- 2016548
- PAR ID:
- 10529045
- Publisher / Repository:
- The 36th International Conference on Scientific and Statistical Database Management (SSDBM)
- Date Published:
- Subject(s) / Keyword(s):
- Side-Channel Attack Timing Attack Data Privacy
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract—Recent work has demonstrated the security risk associated with micro-architecture side-channels. The cache timing side-channel is a particularly popular target due to its availability and high leakage bandwidth. Existing proposals for defending cache side-channel attacks either degrade cache performance and/or limit cache sharing, hence, should only be invoked when the system is under attack. A lightweight monitoring mechanism that detects malicious micro-architecture manipulation in realistic environments is essential for the judicious deployment of these defense mechanisms. In this paper, we propose PREDATOR, a cache side-channel attack detector that identifies cache events caused by an attacker. To detect side-channel attacks in noisy environments, we take advantage of the observation that, unlike non-specific noises, an active attacker alters victim’s micro-architectural states on security critical accesses and thus causes the victim extra cache events on those accesses. PREDATOR uses precise performance counters to collect detailed victim’s access information and analyzes location-based deviations. PREDATOR is capable of detecting five different attacks with high accuracy and limited performance overhead in complex noisy execution environments. PREDATOR remains effective even when the attacker slows the attack rate by 256 times. Furthermore, PREDATOR is able to accurately report details about the attack such as the instruction that accesses the attacked data. In the case of GnuPG RSA [20], PREDATOR can pinpoint the square/multiply operations in the Modulo-Reduce algorithm; and in the case of OpenSSL AES [45], it can identify the accesses to the Te-Table.more » « less
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