Cyber Security and Control System Survivability:

Transcription

1 Cyber Security and Control System Survivability: Technical and Policy Challenges Howard F. Lipson, Ph.D. CERT Pittsburgh, PA USA PSERC Tele-Seminar November 1, 2005 CERT is a registered service mark of Carnegie Mellon University

2 Outline 1. A Brief Introduction to Cyber Security 2. Survivability Concepts 3. Control System Survivability Challenges and Research Issues PSERC Tele-Seminar November 1,

3 Cyber security issues The Internet was not designed to resist highly untrustworthy users - Example: IP spoofing The Internet was never designed for tracking and tracing user behavior - billing not based on fine-grained behavior - a packet s source address is untrustworthy - high speed traffic hinders tracking - attacks often cross multiple administrative, jurisdictional and national boundaries - anonymizers impede tracking - link between a user and an IP address is tenuous PSERC Tele-Seminar November 1,

4 Cyber security issues (2) The current threat and usage environment far exceeds the Internet s design parameters - Severe real-time constraints for control systems takes this to a new level The expertise of the average system administrator continues to decline - Poorly-protected hosts (preferably with highbandwidth connections) are compromised and used to as stepping stones to attack other (possibly more well-protected) targets, and to hide the true origin of the attack PSERC Tele-Seminar November 1,

5 Cyber security issues (3) Commercial-off-the-shelf (COTS) software and public domain software are ubiquitous, and widely accessible for experimentation to discover vulnerabilities (which are later exploited by malicious adversaries) Security is usually an afterthought in the software development life cycle - patch and pray is not enough - need security training & education for developers - need to build security in from the start (See PSERC Tele-Seminar November 1,

6 Cyber security issues (4) Systems designed for use on closed (private) networks were not engineered with the security necessary for today s Internet - Policies and procedures (e.g., who has access to what assets) not planned with cyber security in mind Security through obscurity often fails Cyber attacks are often not recognized by the victim PSERC Tele-Seminar November 1,

7 Information Security Model Confidentiality Integrity Availability Processing Storage Transmission Policy & Procedures Technology Education, Training & Awareness NSTISSI 4011: National Training Standard for Information Systems Security Professionals, 1994 PSERC Tele-Seminar November 1,

8 Examples of Security Vulnerabilities Often narrowly defined as exploitable software flaws: Unchecked buffer bounds (buffer overflow) Missing or incorrect validation of input (malformed input interpreted as system commands) Do-it-yourself crypto Insufficient provision of system resources Temporary files accessible or modifiable by unauthorized processes Vulnerabilities in a much broader sense: Lack of security training (e.g., social engineering, phishing ) System misconfiguration (e.g., default password) PSERC Tele-Seminar November 1,

9 Examples of Malware Worms (e.g., Morris worm, Code Red, Slammer) Viruses Trojan horses Logic bombs Scanners (can be used by attackers or defenders) Spyware (e.g., keystroke loggers) Exploit tools and toolkits Blended threats (e.g., W32/Blaster) General trend: more targeted ( day-zero ) attacks PSERC Tele-Seminar November 1,

10 Distributed Denial of Service (DDoS) Botnet a collection of compromised machines that can be remotely controlled by an attacker. Generally poor state of system security throughout the Internet makes very large botnets possible Distributed denial of service attacks are very difficult to defend against or trace. (Active research area.) Extortion by means of DDoS threats is today s cyber incarnation of the protection racket PSERC Tele-Seminar November 1,

11 A Typical DDoS Attack intruder Internet PSERC Tele-Seminar November 1,

12 Step One - Intruder to Handler intruder sends commands to handler intruder Internet PSERC Tele-Seminar November 1,

13 Step Two - Handler to Agents intruder master sends commands to agents Internet PSERC Tele-Seminar November 1,

14 Step Three - Agents to Victim each agent ( zombie ) independently sends traffic to the victim intruder Internet PSERC Tele-Seminar November 1,

15 Why Survivability? Traditional computer security is not adequate to keep highly distributed systems running in the face of cyber attacks. Survivability is an emerging discipline a risk-management-based security paradigm. PSERC Tele-Seminar November 1,

16 The Problem Large-scale highly distributed systems cannot be totally isolated from potential intruders. No amount of system hardening can guarantee that such systems are invulnerable to attack. Increasing complexity of systems provides more opportunity for attackers. Serious consequences if things go wrong. PSERC Tele-Seminar November 1,

17 Attack Sophistication vs. Intruder Technical Knowledge propagation of malicious code DDoS attacks stealth /advanced scanning techniques increase in worms widespread attacks using NNTP to distribute attack sophisticated command & control widespread attacks on DNS infrastructure executable code attacks (against browsers) automated widespread attacks GUI intruder tools hijacking sessions Internet social engineering attacks packet spoofing automated probes/scans widespread denial-of-service attacks techniques to analyze code for vulnerabilities without source code anti-forensic techniques home users targeted distributed attack tools increase in wide-scale Trojan horse distribution Windows-based remote controllable Trojans (Back Orifice) Copyright 2004 Carnegie Mellon University. Reprinted with permission of the CERT Coordination Center. Intruder Knowledge PSERC Tele-Seminar November 1, Attack Sophistication

18 Vulnerability Exploit Cycle Novice Intruders Use Crude Exploit Tools Crude Exploit Tools Distributed Advanced Intruders Discover New Vulnerability Automated Scanning/Exploit Tools Developed Widespread Use of Automated Scanning/Exploit Tools Intruders Begin Using New Types of Exploits Time PSERC Tele-Seminar November 1,

19 5,000 4,500 4,000 Carnegie Mellon University Number of Vulnerabilities Reported to the CERT/CC 4,129 3,784 3,780 3,500 3,000 2,500 Total vulnerabilities reported (1995-2Q,2005): 19, ,437 2,874 2,000 1,500 1,000 1, st half 2005 PSERC Tele-Seminar November 1,

20 In the beginning... Can we build DoD systems that will continue to operate despite a successful cyber-attack? DARPA (Survivability Program) Late 1995, early 1996 PSERC Tele-Seminar November 1,

21 Survivability Survivability is the ability of a system to fulfill its mission, in a timely manner, in the presence of attacks, failures, or accidents. Attack Recover Resist Adapt Recognize PSERC Tele-Seminar November 1,

22 3 R s of Survivability Resistance ability of a system to repel attacks Recognition ability to recognize attacks and the extent of damage Recovery ability to restore essential services during attack, and recover full services after attack PSERC Tele-Seminar November 1,

23 For Short-term Survivability Deal with the effects of a crisis (survivability scenario): Car rounding a sharp curve is about to veer off a cliff. A guardrail is a survivability solution, whether the underlying cause is: Ice on the road Drunken driver Brakes have been tampered with For long-term survivability: Do the forensics! PSERC Tele-Seminar November 1,

24 An Analogy Is Becoming Reality Emerging trend: -by-wire replacing mechanical and hydraulic control linkages. = { fly, steer, brake,... } Today, Power steering degrades to difficult but functional manual steering Power braking degrades to manual braking Tomorrow? PSERC Tele-Seminar November 1,

25 For Long-term Survivability System adaptation and evolution is essential, because New vulnerabilities are discovered New attack patterns appear Continual attacker-defender escalation Underlying technologies change Collaborators become competitors Political, social, legal changes Missions evolve, or change drastically PSERC Tele-Seminar November 1,

26 Traditional Assumptions for Information Security Clearly defined boundaries Central administrative control Global visibility Trustworthy insiders Fortress Model PSERC Tele-Seminar November 1,

27 Today s Computing Environment Everything on the previous slide PSERC Tele-Seminar November 1,

28 The New Computing Environment Changes Everything Open, highly distributed systems Boundaries are ill-defined (complex physical and logical perimeters) No central (or unified) administrative control No global visibility Untrustworthy insiders - includes incomplete and imprecise information about software: COTS, Java applets, Active controls, etc. Unknown participants Large scale, distributed, coordinated attacks Survival at risk PSERC Tele-Seminar November 1,

29 Unbounded Systems No unified administrative control No global visibility Untrustworthy insiders Lack of complete, timely information PSERC Tele-Seminar November 1,

30 Bounded Thinking in an Unbounded World PSERC Tele-Seminar November 1,

31 Survivability Survivability is the ability of a system to fulfill its mission, in a timely manner, in the presence of attacks, failures, or accidents. Attack Recover Resist Adapt Recognize PSERC Tele-Seminar November 1,

32 Fundamental Assumption No individual component of a system is immune to all attacks, accidents, and design errors. PSERC Tele-Seminar November 1,

33 Fundamental Goal The mission must survive. Not any individual component Not even the system itself PSERC Tele-Seminar November 1,

34 Mission A very high level statement of context-dependent requirements: (1) Under normal usage (2) Under stress... graceful degradation... essential services maintained PSERC Tele-Seminar November 1,

35 Example: Mission of the Titanic Under normal conditions: Luxurious transatlantic transportation Under stress: Buoyancy PSERC Tele-Seminar November 1,

36 Example: Mission of the US Electric Power Industry Under Deregulation Reliably and profitably generate and supply electricity wherever and whenever it is needed in North America. PSERC Tele-Seminar November 1,

37 Survivability Requirements Mission-critical functionality (alternate sets of) minimum essential services graceful degradation of services Mission-critical software quality attributes security, safety, reliability, performance, usability Requirements for the 3 R s and evolution PSERC Tele-Seminar November 1,

38 The New Paradigm Survivability versus Security Security is a technical specialty that provides generic solutions that are largely independent of the mission being protected. Survivability is a blend of security and missionspecific risk management. Survivability solutions require participation from all aspects of an organization: technical and business (and other stakeholders) intense collaboration between domain experts and security/survivability experts. PSERC Tele-Seminar November 1,

39 Some Techniques & Methods Security Fortress model: firewalls, security policy Authentication, access control (insider trust) Encryption Intrusion detection (recovery secondary) Auditing, integrity checking, monitoring Success criteria: - binary: attack succeeds or fails - follow industry standard practices PSERC Tele-Seminar November 1,

40 Survivability Techniques & Methods Security techniques where applicable Diversity, redundancy Trust validation Recovery (largely automated) Mission-specific risk management - includes contingency (disaster) planning Emergent algorithms Success criterion: - mission fulfillment graceful degradation essential services maintained Solutions can transcend the system PSERC Tele-Seminar November 1,

41 Characteristics of Survivability Survivability is an emergent property of a system. Desired system-wide properties emerge from local actions and distributed cooperation. An emergent property need not be a property of any individual node or link. PSERC Tele-Seminar November 1,

42 Some Survivability Research Approaches Survivable Systems Analysis Method Emergent Algorithms Survivable Systems Simulation PSERC Tele-Seminar November 1,

43 Survivable Systems Analysis Understand survivability risks for your system: - What system services must survive attacks, accidents, and failures? - What architectural elements aid in resistance, recognition, and recovery? Identify mitigating strategies: - What architecture changes can improve survivability - Which changes have the highest payoff? PSERC Tele-Seminar November 1,

44 Survivable System Analysis Map Intrusion Scenario Softspot Effects Architecture Strategies for Resistance Recognition Recovery (Scenario 1) Current Recommended (Scenario n) Current Recommended Defines survivability strategies for the three R s based on intrusion softspots Relates survivability strategies to the architecture Makes recommendations for architecture modifications Provides basis for risk analysis, cost-benefit trade-offs PSERC Tele-Seminar November 1,

45 Emergent Algorithms Simple Local Actions + Simple Near Neighbor Interactions => Complex Global Properties Autonomous distributed agents such that if sufficiently many act as intended, desired global properties will emerge. Distributed computations that fulfill mission requirements by exploiting the characteristics of unbounded systems. PSERC Tele-Seminar November 1,

46 Survivable Systems Simulation Easel Emergent Algorithm Simulation Environment and Language Research Goals: Advance scientific knowledge of survivable systems Improve survivability of mission-critical systems Provide tools and methods for survivability engineering EASEL -- Version 3.0 (Download) PSERC Tele-Seminar November 1,

47 Survivability Summary Security provides generic technical solutions binary fortress model leave security to the experts Survivability is a blend of security and missionspecific risk management graceful degradation essential services maintained all stakeholders must contribute - domain experts must be full partners PSERC Tele-Seminar November 1,

48 Internet-connected Control System Internet The Concept IT Business System Firewall Control System Reality PSERC Tele-Seminar November 1,

49 A further dose of reality... Internet IT Business System Firewall Control System Reality PSERC Tele-Seminar November 1,

50 Internet connectivity issues Control systems now faced with all the engineering issues associated with Internet connectivity Exposed to general Internet malware and attacks Subject to targeted attacks ( day-zero attacks) for which no attack signatures are available Subject to probes and vulnerability scans in preparation for attack Denial of service attacks, tampering with monitoring results, or injecting malicious control requests can have disastrous consequences PSERC Tele-Seminar November 1,

51 Internet connectivity issues (2) Control system devices and protocols designed for a closed system environment don t have the security properties needed in an open environment - no strong authentication - no encryption CPU power and storage may be too limited to support needed security tasks (e.g., encryption) Security through obscurity will often fail IT or security staff may be unaware of all Internet access points or other remote access PSERC Tele-Seminar November 1,

52 Internet connectivity issues (3) Blended threats (for example, physical and cyber, or multiple types of cyber attack) are possible Security and survivability degrade over time, so continual adaptation / evolution is necessary Traditional long replacement / evolution cycle versus the need to react quickly to security advisories How can you resolve the need for rapid application of security patches with the necessity for extremely careful testing and evaluation of those patches in a control system environment? PSERC Tele-Seminar November 1,

53 Internet connectivity issues (4) As control system devices (components) move from proprietary protocols towards open standards, for use across multiple industries, the vulnerability landscape may begin to resemble that of COTS products on the Internet today. Need education and training (operators, managers, software developers), new policies and procedures (including changes to physical security to protect cyber assets) Need an industry-wide incident emergency response capability, specialized for control systems PSERC Tele-Seminar November 1,

54 Some Survivability Research Issues PSERC Tele-Seminar November 1,

55 Survivability Research Issues How do you assess and measure the survivability of control systems? How do you effectively model, simulate, and visualize survivability in the control system domain? What are the necessary capabilities of a test bed for control system security and survivability? INL s Control System Security Center PSERC Tele-Seminar November 1,

56 Survivability Research Issues (2) What architectural approaches are best? - context (scenario and domain) dependent - must be capable of rapid evolution What control system architectures (and component mix) provide the redundancy and true diversity needed to contribute to a high assurance of survivability? How can control system devices (components) be designed (what security and survivability properties must they have) so that they can demonstrably contribute to the overall survivability of the composite system (or system of systems)? PSERC Tele-Seminar November 1,

57 Survivability Research Issues (3) What methodologies could help incorporate survivability into the engineering life cycle for control systems? How do you manage the risks and tradeoffs to design survivable and affordable control systems? How do you design control systems that can sustain their survivability in the face of everescalating attacker capabilities? PSERC Tele-Seminar November 1,

58 Survivability Research Issues (4) What are the survivability strategies for dealing with legacy devices versus web-enabled devices? How can society s public policy decisions be translated into survivability solutions? What economic incentives for vendors, or what regulatory-legal environment would lead to enhanced survivability for control systems? PSERC Tele-Seminar November 1,

59 For further reading Howard F. Lipson, Tracking and Tracing Cyber-Attacks: Technical Challenges and Global Policy Issues, SEI Special Report, November Howard F. Lipson and David A. Fisher, Survivability A New Technical and Business Perspective on Security, Proceedings of the 1999 New Security Paradigms Workshop, Caledon Hills, ON, Sept , 1999, Association for Computing Machinery, New York, NY. Jelena Mirkovic, Sven Dietrich, David Dittrich, and Peter Reiher, Internet Denial of Service: Attack and Defense Mechanisms, Prentice Hall, Frederick Sheldon, Tom Potok, Andy Loebl, and Axel Krings and Paul Oman, Energy Infrastructure Survivability, Inherent Limitations, Obstacles and Mitigation Strategies, Proceedings of PowerCon 2003, IASTED International Conference, New York, NY. Joseph Weiss, Cyber Security Meets Plant Politics Don t Neglect Your Control System, InTech, ISA, July 1, ContentDisplay.cfm&ContentID=45287 More on survivability research is available at: PSERC Tele-Seminar November 1,

60 Contact Info Howard F. Lipson, Ph.D. Sr. Member of the Technical Staff CERT Pittsburgh, PA USA Adjunct Professor Department of Engineering and Public Policy Carnegie Mellon University PSERC Tele-Seminar November 1,