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oai:www.ideals.illinois.edu:2142/109512 2023-07-11 col_2142_5131 col_2142_10761 com_2142_5130 com_2142_10755 com_2142_234

Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2022-12-01 The student, Chien-Ying Chen, accepted the attached license on 2020-11-30 at 03:44. The student, Chien-Ying Chen, submitted this Dissertation for approval on 2020-11-30 at 03:57. Mohan, Sibin Mohan, Sibin Nahrstedt, Klara Borisov, Nikita Bobba, Rakesh B. Pellizzoni, Rodolfo Chen, Chien-Ying 2021-03-05T21:42:43Z 2021-03-05T21:42:43Z 2023-03-05T21:43:00Z 2020-11-30 2020-12 This dissertation aims to address the problem of the side-channels caused by the deterministic nature embedded in the real-time schedulers in preemptive real-time systems (RTS). The dissertation explores the problem by postulating that there exist timing-based side-channels (i.e., scheduler side-channels) that enable adversaries to gauge the behavior of the system with high precision in preemptive RTS and that the RTS can be protected by diversifying the real-time schedules. To validate this hypothesis, the work is divided into three groups to tackle the following three key challenges: • Validate the presence of the scheduler side-channels in preemptive RTS. • Protect the RTS by diversifying the real-time schedule. • Evaluate the risks against the scheduler side-channels and the efficacy of a defense scheme. The dissertation shows that the scheduler side-channels exist in both classes of widely used preemptive RTS (i.e., fixed-priority RTS and dynamic-priority RTS) and can leak critical task information using a user-space, non-privileged task. Such information can be leveraged by other collaborative attacks (e.g., advanced persistent threat attacks) to pose a serious threat to systems. A study on the schedule randomization technique as a defense strategy is conducted and shows that, while being effective in disturbing the repeated patterns in the schedule, there exist trade-offs (e.g., the scheduling overhead) and shortcomings (e.g., ineffectiveness in the face of real-time constraints.) Based on the lesson learned, the dissertation introduces the notion of “schedule indistinguishability” and presents a defense scheme that provides security guarantees to critical tasks by achieving the schedule indistinguishability. The scheduler relaxes the real-time constraints and add random noise drawn from bounded Laplace distribution to the task’s execution patterns to hide the repeated patterns from the task schedule. The dissertation further introduces a security evaluation framework consisting of diverse metrics that capture the unique characteristics of real-time schedules and scheduler side-channels to better evaluate the risks for a given RTS. The work is concluded by assessing the developed scheduler against scheduler side-channels with using the introduced security evaluation framework. This Dissertation was approved for publication on 2020-11-30 at 14:53. DSpace SAF Submission Ingestion Package generated from Vireo submission #15981 on 2021-03-04 at 16:20:00 Made available in DSpace on 2021-03-05T21:42:43Z (GMT). No. of bitstreams: 3 CHEN-DISSERTATION-2020.pdf: 5645398 bytes, checksum: 738323cc32d19749b6b3071d17dc4af7 (MD5) LICENSE.txt: 4212 bytes, checksum: ee4a7eed1022032b9ee5b46d64757f20 (MD5) PROQUEST_LICENSE.txt: 4558 bytes, checksum: ecc3c9fded148fe9c134d148de456b20 (MD5) Previous issue date: 2020-11-30 Embargo set by: Seth Robbins for item 117217 Lift date: 2023-03-05T21:43:00Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system U of I Only application/pdf http://hdl.handle.net/2142/109512 en Copyright 2020 Chien-Ying Chen Scheduler Side-Channels Real-Time Systems RTS Scheduler side-channels in preemptive real-time systems: attack and defense techniques text Thesis Computer Science Computer Science University of Illinois at Urbana-Champaign Dissertation Ph.D.