Publications
Guidelines for secure small satellite design and implementation: FY18 Cyber Security Line-Supported Program
February 6, 2019
Project Report
Published in:
MIT Lincoln Laboratory Report LSP-249
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Summary
We are on the cusp of a computational renaissance in space, and we should not bring past terrestrial missteps along. Commercial off-the-shelf (COTS) processors -- much more powerful than traditional rad-hard devices -- are increasingly used in a variety of low-altitude, short-duration CubeSat class missions. With this new-found headroom, the incessant drumbeat of "faster, cheaper, faster, cheaper" leads a familiar march towards Linux and a menagerie of existing software packages, each more bloated and challenging to secure than the last. Lincoln Laboratory has started a pilot effort to design and prototype an exemplar secure satellite processing platform, initially geared toward CubeSats but with a clear path to larger missions and future high performance rad-hard processors. The goal is to provide engineers a secure "grab-and-go" architecture that doesn't unduly hamstring aggressive build timelines yet still provides a foundation of security that can serve adopting systems well, as well as future systems derived from them. This document lays out the problem space for cybersecurity in this domain, derives design guidelines for future secure space systems, proposes an exemplar architecture that implements the guidelines, and provides a solid starting point for near-term and future satellite processing.
Summary
We are on the cusp of a computational renaissance in space, and we should not bring past terrestrial missteps along. Commercial off-the-shelf (COTS) processors -- much more powerful than traditional rad-hard devices -- are increasingly used in a variety of low-altitude, short-duration CubeSat class missions. With this new-found headroom, the...
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Generating a multiple-prerequisite attack graph
May 17, 2016
Published in:
PATENT-9344444
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In one aspect, a method to generate an attack graph includes determining if a potential node provides a first precondition equivalent to one of preconditions provided by a group of preexisting nodes on the attack graph. The group of preexisting nodes includes a first state node, a first vulnerability instance node, a first prerequisite node, and a second state node. The method also includes, if the first precondition is equivalent to one of the preconditions provided by the group of preexisting nodes, coupling a current node to a preexisting node providing the precondition equivalent to the first precondition using a first edge and if the first precondition is not equivalent to one of the preconditions provided by the group of preexisting nodes, generating the potential node as a new node on the attack graph and coupling the new node to the current node using a second edge.
Summary
In one aspect, a method to generate an attack graph includes determining if a potential node provides a first precondition equivalent to one of preconditions provided by a group of preexisting nodes on the attack graph. The group of preexisting nodes includes a first state node, a first vulnerability instance...
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Robust keys from physical unclonable functions
May 6, 2014
Conference Paper
Published in:
Proc. 2014 IEEE Int. Symp. on Hardware-Oriented Security and Trust, HOST, 6-7 May 2014.
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Weak physical unclonable functions (PUFs) can instantiate read-proof hardware tokens (Tuyls et al. 2006, CHES) where benign variation, such as changing temperature, yields a consistent key, but invasive attempts to learn the key destroy it. Previous approaches evaluate security by measuring how much an invasive attack changes the derived key (Pappu et al. 2002, Science). If some attack insufficiently changes the derived key, an expert must redesign the hardware. An unexplored alternative uses software to enhance token response to known physical attacks. Our approach draws on machine learning. We propose a variant of linear discriminant analysis (LDA), called PUF LDA, which reduces noise levels in PUF instances while enhancing changes from known attacks. We compare PUF LDA with standard techniques using an optical coating PUF and the following feature types: raw pixels, fast Fourier transform, short-time Fourier transform, and wavelets. We measure the true positive rate for valid detection at a 0% false positive rate (no mistakes on samples taken after an attack). PUF LDA improves the true positive rate from 50% on average (with a large variance across PUFs) to near 100%. While a well-designed physical process is irreplaceable, PUF LDA enables system designers to improve the PUF reliability-security tradeoff by incorporating attacks without redesigning the hardware token.
Summary
Weak physical unclonable functions (PUFs) can instantiate read-proof hardware tokens (Tuyls et al. 2006, CHES) where benign variation, such as changing temperature, yields a consistent key, but invasive attempts to learn the key destroy it. Previous approaches evaluate security by measuring how much an invasive attack changes the derived key...
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Achieving cyber survivability in a contested environment using a cyber moving target
May 1, 2011
Journal Article
Published in:
High Frontier, Vol. 7, No. 3, May 2011, pp. 9-13.
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We describe two components for achieving cyber survivability in a contested environment: an architectural component that provides heterogeneous computing platforms and an assessment technology that complements the architectural component by analyzing the threat space and triggering reorientation based on the evolving threat level. Together, these technologies provide a cyber moving target that dynamically changes the properties of the system to disadvantage the adversary and provide resiliency and survivability.
Summary
We describe two components for achieving cyber survivability in a contested environment: an architectural component that provides heterogeneous computing platforms and an assessment technology that complements the architectural component by analyzing the threat space and triggering reorientation based on the evolving threat level. Together, these technologies provide a cyber moving...
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Modeling modern network attacks and countermeasures using attack graphs
December 7, 2009
Conference Paper
Published in:
ACSAC 2009, Annual Computer Security Applications Conf., 7 December 2009, pp. 117-126.
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By accurately measuring risk for enterprise networks, attack graphs allow network defenders to understand the most critical threats and select the most effective countermeasures. This paper describes substantial enhancements to the NetSPA attack graph system required to model additional present-day threats (zero-day exploits and client-side attacks) and countermeasures (intrusion prevention systems, proxy firewalls, personal firewalls, and host-based vulnerability scans). Point-to-point reachability algorithms and structures were extensively redesigned to support "reverse" reachability computations and personal firewalls. Host-based vulnerability scans are imported and analyzed. Analysis of an operational network with 85 hosts demonstrates that client-side attacks pose a serious threat. Experiments on larger simulated networks demonstrated that NetSPA's previous excellent scaling is maintained. Less than two minutes are required to completely analyze a four-enclave simulated network with more than 40,000 hosts protected by personal firewalls.
Summary
By accurately measuring risk for enterprise networks, attack graphs allow network defenders to understand the most critical threats and select the most effective countermeasures. This paper describes substantial enhancements to the NetSPA attack graph system required to model additional present-day threats (zero-day exploits and client-side attacks) and countermeasures (intrusion prevention...
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An interactive attack graph cascade and reachability display
October 29, 2007
Conference Paper
Published in:
VizSEC 2007, Proc. of the Workshop on Visualization for Computer Security, 29 October 2007, pp. 221-236.
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Attack graphs for large enterprise networks improve security by revealing critical paths used by adversaries to capture network assets. Even with simplification, current attack graph displays are complex and difficult to relate to the underlying physical networks. We have developed a new interactive tool intended to provide a simplified and more intuitive understanding of key weaknesses discovered by attack graph analysis. Separate treemaps are used to display host groups in each subnet and hosts within each treemap are grouped based on reachability, attacker privilege level, and prerequisites. Users position subnets themselves to reflect their own intuitive grasp of network topology. Users can also single-step the attack graph to successively add edges that cascade to show how attackers progress through a network and learn what vulnerabilities or trust relationships allow critical steps. Finally, an integrated reachability display demonstrates how filtering devices affect host-to-host network reachability and influence attacker actions. This display scales to networks with thousands of hosts and many subnets. Rapid interactivity has been achieved because of an efficient C++ computation engine (a program named NetSPA) that performs attack graph and reachability computations, while a Java application manages the display and user interface.
Summary
Attack graphs for large enterprise networks improve security by revealing critical paths used by adversaries to capture network assets. Even with simplification, current attack graph displays are complex and difficult to relate to the underlying physical networks. We have developed a new interactive tool intended to provide a simplified and...
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Practical attack graph generation for network defense
December 11, 2006
Conference Paper
Published in:
Proc. of the 22nd Annual Computer Security Applications Conf., IEEE, 11-15 December 2006, pp.121-130.
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Attack graphs are a valuable tool to network defenders, illustrating paths an attacker can use to gain access to a targeted network. Defenders can then focus their efforts on patching the vulnerabilities and configuration errors that allow the attackers the greatest amount of access. We have created a new type of attack graph, the multiple-prerequisite graph, that scales nearly linearly as the size of a typical network increases. We have built a prototype system using this graph type. The prototype uses readily available source data to automatically compute network reachability, classify vulnerabilities, build the graph, and recommend actions to improve network security. We have tested the prototype on an operational network with over 250 hosts, where it helped to discover a previously unknown configuration error. It has processed complex simulated networks with over 50,000 hosts in under four minutes.
Summary
Attack graphs are a valuable tool to network defenders, illustrating paths an attacker can use to gain access to a targeted network. Defenders can then focus their efforts on patching the vulnerabilities and configuration errors that allow the attackers the greatest amount of access. We have created a new type...
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Validating and restoring defense in depth using attack graphs
October 23, 2006
Conference Paper
Published in:
IEEE Military Communications Conference MILCOM 2006, 23-25 October 2006, pp. 3720-3729.
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Defense in depth is a common strategy that uses layers of firewalls to protect Supervisory Control and Data Acquisition (SCADA) subnets and other critical resources on enterprise networks. A tool named NetSPA is presented that analyzes firewall rules and vulnerabilities to construct attack graphs. These show how inside and outside attackers can progress by successively compromising exposed vulnerable hosts with the goal of reaching critical internal targets. NetSPA generates attack graphs and automatically analyzes them to produce a small set of prioritized recommendations to restore defense in depth. Field trials on networks with up to 3,400 hosts demonstrate that firewalls often do not provide defense in depth due to misconfigurations and critical unpatched vulnerabilities on hosts. In all cases, a small number of recommendations was provided to restore defense in depth. Simulations on networks with up to 50,000 hosts demonstrate that this approach scales well to enterprise-size networks.
Summary
Defense in depth is a common strategy that uses layers of firewalls to protect Supervisory Control and Data Acquisition (SCADA) subnets and other critical resources on enterprise networks. A tool named NetSPA is presented that analyzes firewall rules and vulnerabilities to construct attack graphs. These show how inside and outside...
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Evaluating and strengthening enterprise network security using attack graphs
October 5, 2005
Project Report
Published in:
MIT Lincoln Laboratory Report IA-2
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Assessing the security of large enterprise networks is complex and labor intensive. Current security analysis tools typically examine only individual firewalls, routers, or hosts separately and do not comprehensively analyze overall network security. We present a new approach that uses configuration information on firewalls and vulnerability information on all network devices to build attack graphs that show how far inside and outside attackers can progress through a network by successively compromising exposed and vulnerable hosts. In addition, attack graphs are automatically analyzed to produce a small set of prioritized recommendations to enhance network security. Field trials on networks with up to 3,400 hosts demonstrate the ability to accurately identify a small number of critical stepping-stone hosts that need to be patched to protect against external attackers. Simulation studies on complex networks with more than 40,000 hosts demonstrate good scaling. This analysis can be used for many purposes, including identifying critical stepping-stone hosts to patch or protect with a firewall, comparing the security of alternating network designs, determining the security risk caused by proposed changes in firewall rules or new vulnerabilities, and identifying the most critical hosts to patch when a new vulnerability is announced. Unique aspects of this work are new attack graph generation algorithms that scale to enterprise networks with thousands of hosts, efficient approaches to determine what other hosts and ports in large networks are reachable from each individual host, automatic data importation from network vulnerability scanners and firewalls, and automatic attack graph analyses to generate recommendations.
Summary
Assessing the security of large enterprise networks is complex and labor intensive. Current security analysis tools typically examine only individual firewalls, routers, or hosts separately and do not comprehensively analyze overall network security. We present a new approach that uses configuration information on firewalls and vulnerability information on all network...
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An annotated review of past papers on attack graphs
March 31, 2005
Project Report
Published in:
MIT Lincoln Laboratory Report IA-1
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This report reviews past research papers that describe how to construct attack graphs, how to use them to improve security of computer networks, and how to use them to analyze alerts from intrusion detection systems. Two commercial systems are described [I, 2], and a summary table compares important characteristics of past research studies. For each study, information is provided on the number of attacker goals, how graphs are constructed, sizes of networks analyzed, how well the approach scales to larger networks, and the general approach. Although research has made significant progress in the past few years, no system has analyzed networks with more than 20 hosts, and computation for most approaches scales poorly and would be impractical for networks with more than even a few hundred hosts. Current approaches also are limited because many require extensive and difficult-to-obtain details on attacks, many assume that host-to-host reachability information between all hosts is already available, and many produce an attack graph but do not automatically generate recommendations from that graph. Researchers have suggested promising approaches to alleviate some of these limitations, including grouping hosts to improve scaling, using worst-case default values for unknown attack details, and symbolically analyzing attack graphs to generate recommendations that improve security for critical hosts. Future research should explore these and other approaches to develop attack graph construction and analysis algorithms that can be applied to large enterprise networks.
Summary
This report reviews past research papers that describe how to construct attack graphs, how to use them to improve security of computer networks, and how to use them to analyze alerts from intrusion detection systems. Two commercial systems are described [I, 2], and a summary table compares important characteristics of...
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