Guide to Network Defense and Countermeasures Second Edition Chapter 2 Security Policy Design: Risk Analysis
Objectives Explain the fundamental concepts of risk analysis Describe different approaches to risk analysis Explain the process of risk analysis Describe techniques to minimize risk Guide to Network Defense and Countermeasures, Second Edition 2
Fundamental Concepts of Risk Analysis There is no situation in which security is perfect Risk analysis Determines the threats that face the organization Security policy Statement that spells out What defenses should be configured How the organization will respond to attacks How employees should safely handle the organization s resources Guide to Network Defense and Countermeasures, Second Edition 3
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Risk Analysis Factors Risk is defined as the possibility of damage or loss Risk analysis Study of the likelihood of damage or loss Should encompass hardware, software, and data warehouses Assets Physical assets Data assets Application software assets Personnel assets Guide to Network Defense and Countermeasures, Second Edition 5
Risk Analysis Factors (continued) Threats Events that have not occurred but might occur Threats increase risks Can be universal or specific to your systems Circumstance-specific threat examples Power supply Crime rate Facility-related Industry The seriousness of a threat depends on the probability that it will occur Guide to Network Defense and Countermeasures, Second Edition 6
Risk Analysis Factors (continued) Probabilities Factors that affect the probability that a threat will actually occur Geographic Physical location Habitual Exposure Increases if you have factors that increase threat probabilities Make a list and rank your threats probabilities Guide to Network Defense and Countermeasures, Second Edition 7
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Risk Analysis Factors (continued) Vulnerabilities Situations or conditions that increase a threat probability Which in turn increases risk Examples OS flaws Application software flaws Poorly configured firewalls or packet filters Unprotected passwords and log files Wireless networks Guide to Network Defense and Countermeasures, Second Edition 9
Risk Analysis Factors (continued) Consequences Significance of an attack impact Some consequences can be estimated Some consequences are difficult to anticipate Return on investment (ROI) Helps you calculate your losses after an attack You can compare your losses with the cost of your security measures Security measures costs should always be less than your losses Guide to Network Defense and Countermeasures, Second Edition 10
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Risk Analysis Factors (continued) Safeguards Measures you can take to reduce threats Examples include Firewalls and IDSs Locking doors Using passwords and encryption Residual risk What is left over after countermeasures and defenses are implemented Guide to Network Defense and Countermeasures, Second Edition 13
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Approaches to Risk Analysis Survivable Network Analysis (SNA) Threat and Risk Assessment (TRA) Guide to Network Defense and Countermeasures, Second Edition 15
Survivable Network Analysis Security process developed by the CERT Coordination Center group Assumes that a system will be attacked Leads you through a four-step process designed to ensure the survivability of a network Network key properties Resistance Recognition Recovery Adaptation and evolution Guide to Network Defense and Countermeasures, Second Edition 16
Survivable Network Analysis (continued) Fault tolerance Capability of an object to continue operations despite a failure SNA steps System definition Essential capability definition Compromisable capability definition Survivability analysis Guide to Network Defense and Countermeasures, Second Edition 17
Threat and Risk Assessment TRA approaches risk analysis from the standpoint of threats and risks to an organization s assets TRA steps Asset definition Threat assessment Risk assessment Recommendations TRA is carried out in different ways by security agencies all over the world Guide to Network Defense and Countermeasures, Second Edition 18
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Risk Analysis: An Ongoing Process Risk analysis is not a one-time activity Evolves to take into account an organization s changing size and activities Initial risk analysis Used to formulate a security policy New threats and intrusions Create the need for a reassessment of the risk Guide to Network Defense and Countermeasures, Second Edition 21
Risk Analysis: General Activities to Follow Risk analysis Group of related activities that follow a sequence Sequence of activities Holding initial team sessions Conduction assets valuation Evaluating vulnerability Calculating risk Guide to Network Defense and Countermeasures, Second Edition 22
Analyzing Economic Impacts Estimating financial impact or losses You can use different statistics models Or a software program such as Project Risk Analysis by Katmar Software Basic information to estimate Likely cost Low cost High cost Monte Carlo simulation Analytical method that simulates real-life system by randomly generating values for variables Guide to Network Defense and Countermeasures, Second Edition 23
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Deciding How to Minimize Risk Risk management Process of identifying, choosing, and setting up countermeasures justified by the risk you identify Countermeasures go into your security policy Guide to Network Defense and Countermeasures, Second Edition 27
Securing Hardware Think about obvious kinds of physical protection Such as environmental conditions Lock up your hardware Decide which devices you want to be locked Pay special attention to laptops Laptops can be lost or stolen easily Install startup passwords and screen saver passwords Experienced thieves can circumvent them though Encrypt files with programs such as PGP Guide to Network Defense and Countermeasures, Second Edition 28
Securing Hardware (continued) Conduction a Hardware inventory Make a list of servers, routers, cables, computers, printers, and other hardware Be sure to include your company s network assets Make a topology map of your network Guide to Network Defense and Countermeasures, Second Edition 29
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Ranking Resources To Be Protected Rank resources in order of importance Values can be arbitrary numbers Focus your security efforts on most critical resources first Work in cooperation with your team and higher management Guide to Network Defense and Countermeasures, Second Edition 31
Securing Information Electronic assets Word processing, spreadsheet, Web page, and other documents Logical assets E-mail messages, any records of instant messaging conversations, and log files Data assets Personnel, customer, and financial information Guide to Network Defense and Countermeasures, Second Edition 32
Securing Information (continued) Maintaining customer and employee privacy Isolate critical information from the Internet Move information from the original directory to a computer that is not connected to the Internet Configure backup software to save critical files Other measures Encryption Message filtering Data encapsulation Redundancy Backups Guide to Network Defense and Countermeasures, Second Edition 33
Securing Information (continued) Protecting Corporate Information Measures include Never leave company-owned laptops unattended Always password-protect information on corporate devices Encrypt and financial information Password-protect all job records and customer information Restrict personnel information to human resources staff and/or upper management Guide to Network Defense and Countermeasures, Second Edition 34
Conducting Routine Analysis Risk analysis is an ongoing process Company s situation changes constantly Risk analysis should be done routinely to include these changes Consider the following questions How often will a risk analysis be performed? Who will conduct the risk analysis? Do all hardware and software resources need to be reviewed every time? Human emotions can influence risk evaluations Some companies do not allow these calculations to be done manually Guide to Network Defense and Countermeasures, Second Edition 35
Handling Security Incidents Security policy should state how you will respond to break-ins Fill out a form to record what happened Incident-handling procedures Describe who will respond to security incidents Describe the kinds of incidents to be addressed Alarms sent by intrusion detection systems Repeated unsuccessful logon attempts Unexplained changes to data or deletion of records System crashes Poor system performance Guide to Network Defense and Countermeasures, Second Edition 36
Guide to Network Defense and Countermeasures, Second Edition 37
Handling Security Incidents (continued) Assembling a response team Security policy should state which security staff need to be notified in case of an incident Security incident response team (SIRT) Staff people designated to take countermeasures when an incident is reported SIRT contains IT operations and technical support staff IT application staff Chief security officer Information security specialists Others Guide to Network Defense and Countermeasures, Second Edition 38
Handling Security Incidents (continued) Escalation procedure Set of roles, responsibilities, and measures taken in response to a security incident Guide to Network Defense and Countermeasures, Second Edition 39
Handling Security Incidents (continued) Including worst-case scenarios Worst-case scenarios Descriptions of the worst consequences to an organization if a threat happens Might be unlikely Can help you determine the value of a resource at risk Guide to Network Defense and Countermeasures, Second Edition 40
Summary Risk Analysis plays a central role in defining a security policy Risk analysis covers company s computer hardware, software, and informational assets Your first task is to assess the level of risk to your network and its users Determine countermeasures for minimizing risk Assess threats to your network and the probability that they might happen Determine safeguards and countermeasures Guide to Network Defense and Countermeasures, Second Edition 41