Publications
Securing the satellite software stack
March 1, 2024
Conference Paper
Published in:
Workshop on Security of Space and Satellite Systems, SpaceSec, 1 March 2024.
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Satellites and the services enabled by them, like GPS, real-time world-wide imaging, weather tracking, and worldwide communication, play an increasingly important role in modern life. To support these services satellite software is becoming increasingly complex and connected. As a result, concerns about its security are becoming prevalent. While the focus of security for satellites has historically been on encrypting the communications link, we argue that a fuller consideration of the security of satellites is necessary and presents unique challenges. Satellites are becoming increasingly accessible to attackers–thanks to supply chain attacks and Internet connected ground stations–and present a unique set of challenges for security practitioners. These challenges include the lack of any real ability for a human to be physically present to repair or recover these systems, a focus on safety and availability over confidentiality and integrity, and the need to deal with radiation-induced faults. This work characterizes the cyber threats to satellite systems, surveys the unique challenges for satellite software, and presents a future vision for research in this area.
Summary
Satellites and the services enabled by them, like GPS, real-time world-wide imaging, weather tracking, and worldwide communication, play an increasingly important role in modern life. To support these services satellite software is becoming increasingly complex and connected. As a result, concerns about its security are becoming prevalent. While the focus...
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On randomization in MTD systems
November 7, 2022
Conference Paper
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Proc. of the 9th ACM Workshop on Moving Target Defense, MTD ’22, 7 November 2022.
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Randomization is one of the main strategies in providing security in moving-target-defense (MTD) systems. However, randomization has an associated cost and estimating this cost and its impact on the overall system is crucial to ensure adoption of the MTD strategy. In this paper we discuss our experience in attempting to estimate the cost of path randomization in a message transmission system that used randomization of paths in the network. Our conclusions are (i) the cost crucially depends on the underlying network control technology, (ii) one can reduce this cost by better implementation, and (iii) reducing one type of cost may result in increased costs of a different type, for example a higher device cost. These suggest that estimating the cost of randomization is a multivariable optimization problem that requires a full understanding of the system components.
Summary
Randomization is one of the main strategies in providing security in moving-target-defense (MTD) systems. However, randomization has an associated cost and estimating this cost and its impact on the overall system is crucial to ensure adoption of the MTD strategy. In this paper we discuss our experience in attempting to...
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The tale of discovering a side channel in secure message transmission systems
August 13, 2022
Conference Paper
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The Conf. for Failed Approaches and Insightful Losses in Cryptology, CFAIL, 13 August 2022.
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Secure message transmission (SMT) systems provide information theoretic security for point-to-point message transmission in networks that are partially controlled by an adversary. This is the story of a research project that aimed to implement a flavour of SMT protocols that uses "path hopping" with the goal of quantifying the real-life efficiency of the system, and while failing to achieve this initial goal, let to the discovery a side-channel that affects the security of a wide range of SMT implementations.
Summary
Secure message transmission (SMT) systems provide information theoretic security for point-to-point message transmission in networks that are partially controlled by an adversary. This is the story of a research project that aimed to implement a flavour of SMT protocols that uses "path hopping" with the goal of quantifying the real-life...
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The thundering herd: Amplifying kernel interference to attack response times
May 4, 2022
Conference Paper
Published in:
2022 IEEE 28th Real-Time and Embedded Technology and Applications Symp., RTAS, 4-6 May 2022.
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Embedded and real-time systems are increasingly attached to networks. This enables broader coordination beyond the physical system, but also opens the system to attacks. The increasingly complex workloads of these systems include software of varying assurance levels, including that which might be susceptible to compromise by remote attackers. To limit the impact of compromise, u-kernels focus on maintaining strong memory protection domains between different bodies of software, including system services. They enable limited coordination between processes through Inter-Process Communication (IPC). Real-time systems also require strong temporal guarantees for tasks, and thus need temporal isolation to limit the impact of malicious software. This is challenging as multiple client threads that use IPC to request service from a shared server will impact each other's response times. To constrain the temporal interference between threads, modern u-kernels often build priority and budget awareness into the system. Unfortunately, this paper demonstrates that this is more challenging than previously thought. Adding priority awareness to IPC processing can lead to significant interference due to the kernel's prioritization logic. Adding budget awareness similarly creates opportunities for interference due to the budget tracking and management operations. In both situations, a Thundering Herd of malicious threads can significantly delay the activation of mission-critical tasks. The Thundering Herd effects are evaluated on seL4 and results demonstrate that high-priority threads can be delayed by over 100,000 cycles per malicious thread. This paper reveals a challenging dilemma: the temporal protections u-kernels add can, themselves, provide means of threatening temporal isolation. Finally, to defend the system, we identify and empirically evaluate possible mitigations, and propose an admission-control test based upon an interference-aware analysis.
Summary
Embedded and real-time systems are increasingly attached to networks. This enables broader coordination beyond the physical system, but also opens the system to attacks. The increasingly complex workloads of these systems include software of varying assurance levels, including that which might be susceptible to compromise by remote attackers. To limit...
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Practical principle of least privilege for secure embedded systems
May 18, 2021
Conference Paper
Published in:
2021 IEEE 27th Real-Time and Embedded Technology and Applications Symp., RTAS. 18-21 May 2021.
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Many embedded systems have evolved from simple bare-metal control systems to highly complex network-connected systems. These systems increasingly demand rich and feature-full operating-systems (OS) functionalities. Furthermore, the network connectedness offers attack vectors that require stronger security designs. To that end, this paper defines a prototypical RTOS API called Patina that provides services common in featurerich OSes (e.g., Linux) but absent in more trustworthy u-kernel-based systems. Examples of such services include communication channels, timers, event management, and synchronization. Two Patina implementations are presented, one on Composite and the other on seL4, each of which is designed based on the Principle of Least Privilege (PoLP) to increase system security. This paper describes how each of these u-kernels affect the PoLP-based design, as well as discusses security and performance tradeoffs in the two implementations. Results of comprehensive evaluations demonstrate that the performance of the PoLP-based implementation of Patina offers comparable or superior performance to Linux, while offering heightened isolation.
Summary
Many embedded systems have evolved from simple bare-metal control systems to highly complex network-connected systems. These systems increasingly demand rich and feature-full operating-systems (OS) functionalities. Furthermore, the network connectedness offers attack vectors that require stronger security designs. To that end, this paper defines a prototypical RTOS API called Patina that...
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More than a fair share: Network Data Remanence attacks against secret sharing-based schemes
February 23, 2021
Journal Article
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Network and Distributed Systems Security Symp., NDSS, 23-26 February 2021.
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With progress toward a practical quantum computer has come an increasingly rapid search for quantum-safe, secure communication schemes that do not rely on discrete logarithm or factorization problems. One such encryption scheme, Multi-path Switching with Secret Sharing (MSSS), combines secret sharing with multi-path switching to achieve security as long as the adversary does not have global observability of all paths and thus cannot capture enough shares to reconstruct messages. MSSS assumes that sending a share on a path is an atomic operation and all paths have the same delay. In this paper, we identify a side-channel vulnerability for MSSS, created by the fact that in real networks, sending a share is not an atomic operation as paths have multiple hops and different delays. This channel, referred to as Network Data Remanence (NDR), is present in all schemes like MSSS whose security relies on transfer atomicity and all paths having same delay. We demonstrate the presence of NDR in a physical testbed. We then identify two new attacks that aim to exploit the side channel, referred to as NDR Blind and NDR Planned, propose an analytical model to analyze the attacks, and demonstrate them using an implementation of MSSS based on the ONOS SDN controller. Finally, we present a countermeasure for the attacks and show its effectiveness in simulations and Mininet experiments.
Summary
With progress toward a practical quantum computer has come an increasingly rapid search for quantum-safe, secure communication schemes that do not rely on discrete logarithm or factorization problems. One such encryption scheme, Multi-path Switching with Secret Sharing (MSSS), combines secret sharing with multi-path switching to achieve security as long as...
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One giant leap for computer security
April 23, 2020
Journal Article
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IEEE Security & Privacy, Vol. 18, No. 4, July-August 2020.
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Today's computer systems trace their roots to an era of trusted users and highly constrained hardware; thus, their designs fundamentally emphasize performance and discount security. This article presents a vision for how small steps using existing technologies can be combined into one giant leap for computer security.
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Today's computer systems trace their roots to an era of trusted users and highly constrained hardware; thus, their designs fundamentally emphasize performance and discount security. This article presents a vision for how small steps using existing technologies can be combined into one giant leap for computer security.
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Automated discovery of cross-plane event-based vulnerabilities in software-defined networking
February 23, 2020
Conference Paper
Published in:
Network and Distributed Systems Security Symp., NDSS, 23-26 February 2020.
Summary
Software-defined networking (SDN) achieves a programmable control plane through the use of logically centralized, event-driven controllers and through network applications (apps) that extend the controllers' functionality. As control plane decisions are often based on the data plane, it is possible for carefully crafted malicious data plane inputs to direct the control plane towards unwanted states that bypass network security restrictions (i.e., cross-plane attacks). Unfortunately, because of the complex interplay among controllers, apps, and data plane inputs, at present it is difficult to systematically identify and analyze these cross-plane vulnerabilities. We present EVENTSCOPE, a vulnerability detection tool that automatically analyzes SDN control plane event usage, discovers candidate vulnerabilities based on missing event-handling routines, and validates vulnerabilities based on data plane effects. To accurately detect missing event handlers without ground truth or developer aid, we cluster apps according to similar event usage and mark inconsistencies as candidates. We create an event flow graph to observe a global view of events and control flows within the control plane and use it to validate vulnerabilities that affect the data plane. We applied EVENTSCOPE to the ONOS SDN controller and uncovered 14 new vulnerabilities.
Summary
Software-defined networking (SDN) achieves a programmable control plane through the use of logically centralized, event-driven controllers and through network applications (apps) that extend the controllers' functionality. As control plane decisions are often based on the data plane, it is possible for carefully crafted malicious data plane inputs to direct the...
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Security considerations for next-generation operating systems for cyber-physical systems
April 15, 2019
Conference Paper
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1st Intl. Workshop on Next-Generation Operating Systems for Cyber-Physical Systems, NGOSCPS, 15 April 2019.
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Cyber-physical systems (CPSs) are increasingly targeted in high-profile cyber attacks. Examples of such attacks include Stuxnet, which targeted nuclear centrifuges; Crashoverride, and Triton, which targeted power grids; and the Mirai botnet, which targeted internet-of-things (IoT) devices such as cameras to carry out a large-scale distributed denial-of-service (DDoS) attack. Such attacks demonstrate the importance of securing current and future cyber-physical systems. Therefore, next-generation operating systems (OSes) for CPS need to be designed to provide security features necessary, as well as be secure in and of themselves. CPSs are designed with one of three broad classes of OSes: (a) bare-metal applications with effectively no operating system, (b) embedded systems executing on impoverished platforms running an embedded or real-time operating system (RTOS) such as FreeRTOS, or (c) more performant platforms running general purpose OSes such as Linux, sometimes tuned for real-time performance such as through the PREEMPT_RT patch. In cases (a) and (b), the OS, if any, is very minimal to facilitate improved resource utilization in real-time or latency-sensitive applications, especially running on impoverished hardware platforms. In such OSes, security is often overlooked, and many important security features (e.g. process/kernel memory isolation) are notably absent. In case (c), the general-purpose OS inherits many of the security-related features that are critical in enterprise and general-purpose applications, such as virtual memory and address-space layout randomization (ASLR). However, the highly complex nature of general-purpose OSes can be problematic in the development of CPSs, as they are highly non-deterministic and difficult to formally reason about for cyber-physical applications, which often have real-time constraints. These issues motivate the need for a next generation OS that is highly capable, predictable and deterministic for real-time performance, but also secure in the face of many of the next generation of cyber threats. In order to design such a next-generation OS, it is necessary to first reflect on the types of threats that CPSs face, including the attacker intentions and types of effects that can be achieved, as well as the type of access that attackers have. While threat models are not the same for all CPSs, it is important to understand how the threat models for CPSs compare to general-purpose or enterprise computing environments. We discuss these issues next (Sec. 2), before providing insights and recommendations for approaches to incorporate in next-generation OSes for CPS in Sec. 3.
Summary
Cyber-physical systems (CPSs) are increasingly targeted in high-profile cyber attacks. Examples of such attacks include Stuxnet, which targeted nuclear centrifuges; Crashoverride, and Triton, which targeted power grids; and the Mirai botnet, which targeted internet-of-things (IoT) devices such as cameras to carry out a large-scale distributed denial-of-service (DDoS) attack. Such attacks...
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Cross-app poisoning in software-defined networking
October 15, 2018
Conference Paper
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Proc. ACM Conf. on Computer and Communications Security, CCS, 15-18 October 2018, pp. 648-63.
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Software-defined networking (SDN) continues to grow in popularity because of its programmable and extensible control plane realized through network applications (apps). However, apps introduce significant security challenges that can systemically disrupt network operations, since apps must access or modify data in a shared control plane state. If our understanding of how such data propagate within the control plane is inadequate, apps can co-opt other apps, causing them to poison the control plane's integrity. We present a class of SDN control plane integrity attacks that we call cross-app poisoning (CAP), in which an unprivileged app manipulates the shared control plane state to trick a privileged app into taking actions on its behalf. We demonstrate how role-based access control (RBAC) schemes are insufficient for preventing such attacks because they neither track information flow nor enforce information flow control (IFC). We also present a defense, ProvSDN, that uses data provenance to track information flow and serves as an online reference monitor to prevent CAP attacks. We implement ProvSDN on the ONOS SDN controller and demonstrate that information flow can be tracked with low-latency overheads.
Summary
Software-defined networking (SDN) continues to grow in popularity because of its programmable and extensible control plane realized through network applications (apps). However, apps introduce significant security challenges that can systemically disrupt network operations, since apps must access or modify data in a shared control plane state. If our understanding of...
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