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Examining Operations Security

Add a note here Operations security is concerned with the day-to-day practices necessary to first deploy and later maintain a secure system. This section examines these principles.

Add a note here Secure Network Life Cycle Management

Add a note hereThe responsibilities of the operations team pertain to everything that takes place to keep a network, computer systems, applications, and the environment up and running in a secure and protected manner. After the network is set up, the operation tasks begin, including the continual day-to-day maintenance of the environment. These activities are regular in nature and enable the environment, systems, and applications to continue to run correctly and securely.

Add a note hereOperations within a computing environment can pertain to software, personnel, and hardware, but an operations department often focuses only on the hardware and software aspects. Management is responsible for the behavior and responsibilities of employees. The people within operations are responsible for ensuring that systems are protected and that they continue to run in a predictable manner.

Add a note hereThe operations team usually has the following objectives:

  • Add a note herePreventing reoccurring problems

  • Add a note hereReducing hardware failures to an acceptable level

  • Add a note hereReducing the impact of hardware failure or disruption

Add a note hereThis group should investigate any unusual or unexplained occurrences, unscheduled initial program loads, deviations from standards, or other odd or abnormal conditions that take place on the network.

Add a note hereIncluding security early in the information process, in the system design life cycle (SDLC), usually results in less-expensive and more-effective security when compared to adding it to an operational system.

Add a note hereA general SDLC includes five phases:

  1. Add a note hereInitiation

  2. Add a note hereAcquisition and development

  3. Add a note hereImplementation

  4. Add a note hereOperations and maintenance

  5. Add a note hereDisposition

Add a note hereEach of these five phases includes a minimum set of security steps that you need to effectively incorporate security into a system during its development. An organization either uses the general SDLC or develops a tailored SDLC that meets their specific needs. In either case, the National Institute of Standards and Technology (NIST) recommends that organizations incorporate the associated IT security steps of this general SDLC into their development process.

Initiation Phase

Add a note here The initiation phase of the SDLC includes the following:

  • Add a note here Security categorization: This step defines three levels, such as low, moderate, and high, of potential impact on organizations or individuals should a breach of security occur (a loss of confidentiality, integrity, or availability). Security categorization standards help organizations make the appropriate selection of security controls for their information systems.

  • Add a note here Preliminary risk assessment: This step results in an initial description of the basic security needs of the system. A preliminary risk assessment should define the threat environment in which the system will operate.

Acquisition and Development Phase

Add a note hereThe acquisition and development phase of the SDLC includes the following:

  • Add a note here Risk assessment: This step is an analysis that identifies the protection requirements for the system through a formal risk-assessment process. This analysis builds on the initial risk assessment that was performed during the initiation phase, but is more in depth and specific.

  • Add a note here Security functional requirements analysis: This step is an analysis of requirements and can include the following components: system security environment, such as the enterprise information security policy and enterprise security architecture, and security functional requirements.

  • Add a note here Security assurance requirements analysis: This step is an analysis of the requirements that address the developmental activities required and the assurance evidence needed to produce the desired level of confidence that the information security will work correctly and effectively. The analysis, based on legal and functional security requirements, is used as the basis for determining how much and what kinds of assurance are required.

  • Add a note here Cost considerations and reporting: This step determines how much of the development cost you can attribute to information security over the life cycle of the system. These costs include hardware, software, personnel, and training.

  • Add a note here Security planning: This step ensures that you fully document any agreed upon security controls, whether they are just planned or in place. The security plan also provides a complete characterization or description of the information system and attachments or references to key documents that support the information security program of the agency. Examples of documents that support the information security program include a configuration management plan, a contingency plan, an incident response plan, a security awareness and training plan, rules of behavior, a risk assessment, a security test and evaluation results, system interconnection agreements, security authorizations and accreditations, and a plan of action and milestones.

  • Add a note here Security control development: This step ensures that the security controls that the respective security plans describe are designed, developed, and implemented. The security plans for information systems that are currently in operation may call for the development of additional security controls to supplement the controls that are already in place or the modification of selected controls that are deemed less than effective.

  • Add a note here Developmental security test and evaluation: This ensures that security controls that you develop for a new information system are working properly and are effective. Some types of security controls, primarily those controls of a nontechnical nature, cannot be tested and evaluated until the information system is deployed. These controls are typically management and operational controls.

  • Add a note here Other planning components: This step ensures that you consider all the necessary components of the development process when you incorporate security into the network life cycle. These components include the selection of the appropriate contract type, the participation by all the necessary functional groups within an organization, the participation by the certifier and accreditor, and the development and execution of the necessary contracting plans and processes.

Implementation Phase

Add a note hereThe implementation phase of the SDLC includes the following:

  • Add a note here Inspection and acceptance: This step ensures that the organization validates and verifies that the functionality that the specification describes is included in the deliverables.

  • Add a note here System integration: This step ensures that the system is integrated at the operational site where you will deploy the information system for operation. You enable the security control settings and switches in accordance with the vendor instructions and the available security implementation guidance.

  • Add a note here Security certification: This step ensures that you effectively implement the controls through established verification techniques and procedures. This step gives organization officials confidence that the appropriate safeguards and countermeasures are in place to protect the information system of the organization. Security certification also uncovers and describes the known vulnerabilities in the information system.

  • Add a note here Security accreditation: This step provides the necessary security authorization of an information system to process, store, or transmit information that is required. This authorization is granted by a senior organization official and is based on the verified effectiveness of security controls to some agreed upon level of assurance and an identified residual risk to agency assets or operations.

Operations and Maintenance Phase

Add a note hereThe operations and maintenance phase of the SDLC includes the following:

  • Add a note here Configuration management and control: This step ensures that there is adequate consideration of the potential security impacts due to specific changes to an information system or its surrounding environment. Configuration management and configuration control procedures are critical to establishing an initial baseline of hardware, software, and firmware components for the information system and subsequently controlling and maintaining an accurate inventory of any changes to the system.

  • Add a note here Continuous monitoring: This step ensures that controls continue to be effective in their application through periodic testing and evaluation. Security control monitoring, such as verifying the continued effectiveness of those controls over time, and reporting the security status of the information system to appropriate agency officials is an essential activity of a comprehensive information security program.

Disposition Phase

Add a note hereThe disposition phase of the SDLC includes the following:

  • Add a note here Information preservation: This step ensures that you retain information, as necessary, to conform to current legal requirements and to accommodate future technology changes that can render the retrieval method of the information obsolete.

  • Add a note here Media sanitization: This step ensures that you delete, erase, and write over data as necessary.

  • Add a note here Hardware and software disposal: This step ensures that you dispose of hardware and software as directed by the information system security officer.

Add a note here Principles of Operations Security

Add a note hereCertain core principles are part of the secure operations that are intended for information systems security (infosec). The following are among these principles:

  • Add a note here Separation of duties

    • Add a note hereTwo-man control

    • Add a note hereDual operator

  • Add a note here Rotation of duties

  • Add a note here Trusted recovery, which includes the following:

    • Add a note hereFailure preparation

    • Add a note hereSystem recovery

  • Add a note here Change and configuration controls

Separation of Duties

Add a note hereSeparation of duties (SoD) is one of the key concepts of internal control and is the most difficult and sometimes the most costly control to achieve. SoD states that no single individual should have control over two or more phases of a transaction or operation, which makes deliberate fraud more difficult to perpetrate because it requires the collusion of two or more individuals or parties.

Add a note hereThe term SoD is already well-known in financial systems. Companies understand not to combine roles such as receiving checks, approving discounts, depositing cash and reconciling bank statements, approving time cards, and so on.

Add a note here In information systems, segregation of duties helps to reduce the potential impact from the actions/inactions of one person. You should organize IT in a way that achieves adequate SoD.


Note

Add a note hereSoD is also known as segregation of duties.

Add a note hereThe two-man control principle uses two individuals to review and approve the work of the other. This principle provides accountability and reduces things such as fraud. Because of the obvious overhead involved, this practice is usually limited to sensitive duties considered potential security risks.

Add a note hereThe dual-operator principle differs from the two-man control because the task involved actually requires two people. An example of the dual-operator principle is a check that requires two signatures for the bank to accept it, or the safety deposit bank where you have one key and the bank clerk has the second key.


Note

Add a note hereThe dual-operator principle is a technical requirement, whereas two-man control is an administrative or policy decision.

Rotation of Duties

Add a note hereRotation of duties is sometimes called job rotation. To successfully implement this principle, it is important that individuals have the training necessary to complete more than one job. Peer review is usually included in the practice of this principle.

Add a note hereFor example, suppose that a job-rotation scheme has five people rotating through five different roles during the course of a week. Peer review of work occurs whether or not it was intended. When five people do one job in the course of the week, each person is effectively reviewing the work of the others.

Add a note hereThe most obvious benefit of this practice is the great strength and flexibility that would exist within a department because everyone is capable of doing all the jobs. Although the purpose for the practice is rooted in security, you gain an additional business benefit from this breadth of experience of the personnel.

Trusted Recovery

Add a note hereOne of the easiest ways to compromise a system is to make the system restart and compromise it before all of its defenses can be reloaded. For this reason, trusted recovery is a principle of operations security. The trust recovery principle states that you must expect that systems and individuals will experience a failure at some time and you must prepare for this failure. Because you anticipate the failure, you can have a recovery plan for both systems and personnel available and implemented. The most common way to prepare for failure is to back up data on a regular basis.

Add a note hereBacking up data is a normal occurrence in most IT departments and is commonly performed by junior-level staff. However, this is not a very secure operation because backup software uses an account that can bypass file security to back up the files. Therefore, junior-level staff members have access to files that they would ordinarily not be able to access. The same is true if these same junior staff members have the right to restore data.

Add a note here Security professionals propose that a secure backup program contain some of the following practices:

  • Add a note hereA junior staff member is responsible for loading blank media.

  • Add a note hereBackup software uses an account that is unknown to individuals to bypass file security.

  • Add a note hereA different staff member removes the backup media and securely stores it on site while being assisted by another member of the staff.

  • Add a note hereA separate copy of the backup is stored off site and is handled by a third staff member who is accompanied by another staff member.


Note

Add a note hereOne of the easiest ways for attackers to get their hands on a password file (or any other data) is to get a copy of the backup tape, because the backup tape is not always handled or stored securely.

Add a note hereBeing prepared for system failure is an important part of operations security. The following are examples of things that help provide system recovery:

  • Add a note hereOperating systems and applications that have single-user or safe mode help with system recovery.

  • Add a note hereThe ability to recover files that were open at the time of the problem helps ensure a smooth system recovery. The autosave process in many desktop applications is an example of this ability. A memory dump that many operating systems perform upon a system failure is also an example of this ability.

  • Add a note hereThe ability to retain the security settings of a file after a system crash is critical so that the security is not bypassed by forcing a crash.

  • Add a note hereThe ability to recover and retain security settings for critical key system files, such as the Registry, configuration files, password files, and so on, is critical for providing system recovery.

Change and Configuration Control

Add a note hereThe goal of change and configuration controls is to ensure that you use standardized methods and procedures to efficiently handle all changes. To make changes efficient, you should minimize the impact of change-related incidents and improve the day-to-day operations.

Add a note hereA change is defined as an event that results in a new status of one or more configuration items. A change should be approved by management, be cost-effective, and be an enhancement to business processes with a minimum risk to the IT infrastructure and security.

Add a note hereThe three major goals of change and configuration management are as follows:

  • Add a note hereMinimal system and network disruption

  • Add a note herePreparation to reverse changes

  • Add a note hereMore economic utilization of resources

Add a note here To accomplish configuration changes in an effective and safe manor, adhere to the following suggestions:

  • Add a note hereEnsure that the change is implemented in an orderly manner with formalized testing.

  • Add a note hereEnsure that the end users are aware of the coming change (when necessary).

  • Add a note hereAnalyze the effects of the change after it is implemented.

  • Add a note hereReduce the potential negative impact on performance or security, or both.

Add a note hereAlthough the change control process differs from organization to organization, certain patterns emerge in change management. The following are steps in a typical change control process:

Add a note here Step 1

Add a note hereApply to introduce the change.

Add a note here Step 2

Add a note hereCatalogue the proposed change.

Add a note here Step 3

Add a note hereSchedule the change.

Add a note here Step 4

Add a note hereImplement the change.

Add a note here Step 5

Add a note hereReport the change to relevant parties.

Add a note here Network Security Testing

Add a note hereSecurity testing provides insight into the other SDLC activities such as risk analysis and contingency planning. You should document security testing and make them available for staff involved in other IT and security related areas. Typically, you conduct network security testing during the implementation and operational stages, after the system has been developed, installed, and integrated.

Add a note hereDuring the implementation stage, you should conduct security testing and evaluation on specific parts of the system and on the entire system as a whole. Security test and evaluation (ST&E) is an examination or analysis of the protective measures that are placed on an information system after it is fully integrated and operational. The following are the objectives of the ST&E:

  • Add a note hereUncover design, implementation, and operational flaws that could allow the violation of the security policy

  • Add a note hereDetermine the adequacy of security mechanisms, assurances, and other properties to enforce the security policy

  • Add a note hereAssess the degree of consistency between the system documentation and its implementation

Add a note hereOnce a system is operational, it is important to ascertain its operational status. You can conduct many tests to assess the operational status of the system. The types of tests you use and the frequency in which you conduct them depend on the importance of the system and the resources available for testing. You should repeat these tests periodically and whenever you make a major change to the system. For systems that are exposed to constant threat, such as web servers, or systems that protect critical information, such as firewalls, you should conduct tests more frequently.

Security Testing Techniques

Add a note here You can use security testing results in the following ways:

  • Add a note hereAs a reference point for corrective action

  • Add a note hereTo define mitigation activities to address identified vulnerabilities

  • Add a note hereAs a benchmark to trace the progress of an organization in meeting security requirements

  • Add a note hereTo assess the implementation status of system security requirements

  • Add a note hereTo conduct cost and benefit analysis for improvements to system security

  • Add a note hereTo enhance other life cycle activities, such as risk assessments, certification and authorization (C&A), and performance-improvement efforts

Add a note hereThere are several different types of security testing. Some testing techniques are predominantly manual, and other tests are highly automated. Regardless of the type of testing, the staff that sets up and conducts the security testing should have significant security and networking knowledge, including significant expertise in the following areas: network security, firewalls, IPSs, operating systems, programming, and networking protocols, such as TCP/IP.

Add a note hereMany testing techniques are available, including the following:

  • Add a note hereNetwork scanning

  • Add a note hereVulnerability scanning

  • Add a note herePassword cracking

  • Add a note hereLog review

  • Add a note hereIntegrity checkers

  • Add a note hereVirus detection

  • Add a note hereWar dialing

  • Add a note hereWar driving (802.11 or wireless LAN testing)

  • Add a note herePenetration testing

Common Testing Tools

Add a note hereMany testing tools are available in the modern marketplace that you can use to test the security of your systems and networks. The following list is a collection of tools that are quite popular; some of the tools are freeware, some are not:

  • Add a note hereNmap

  • Add a note hereGFI LANguard

  • Add a note hereTripwire

  • Add a note here Nessus

  • Add a note hereMetasploit

  • Add a note hereSuperScan by Foundstone, a division of McAfee


Note

Add a note hereMany other excellent tools exist. This list is only a representative sampling.

Add a note hereSome testing tools are actually hacking tools. Why not try on your network tools before a hacker does? Find the weaknesses on your network before the hacker does and before he exploits them. So, look at two tools that are commonly used.

Add a note hereNmap is the best-known low-level scanner available to the public. It is simple to use and has an array of excellent features that you can use for network mapping and reconnaissance. The basic functionality of Nmap enables the user to do the following:

  • Add a note herePerform classic TCP and UDP port scanning (looking for different services on one host) and sweeping (looking for the same service on multiple systems)

  • Add a note herePerform stealth port scans and sweeps, which are hard to detect by the target host or IPSs

  • Add a note hereIdentify remote operating systems, known as OS fingerprinting, through its TCP idiosyncrasies

Add a note hereAdvanced features of Nmap include protocol scanning, known as Layer 3 port scanning, which can identify Layer 3 protocol support on a host, such as generic routing encapsulation (GRE) support and Open Shortest Path First (OSPF) support, using decoy hosts on the same LAN to mask your identity.

Add a note here Figure 1-18 shows a screen output of ZENMAP, the GUI for Nmap Security Scanner.

Click to collapse
Add a note hereFigure 1-18: ZENMAP (Nmap Security Scanner GUI)

Tip

Add a note hereYou can download the Nmap program from http://www.insecure.org/nmap.

Add a note hereSuperScan Version 4 is an update of the highly popular Microsoft Windows port scanning tool, SuperScan. It runs only on Windows XP and Windows 2000 and requires administrator privileges to run. Windows XP SP2 has removed support for raw sockets, which limits the capability of SuperScan and other scanning tools. Some functionality can be restored by entering the net stop SharedAccess command at the Windows command prompt.

Add a note hereThe following are some of the features of SuperScan Version 4:

  • Add a note hereAdjustable scanning speed

  • Add a note hereSupport for unlimited IP ranges

  • Add a note hereImproved host detection using multiple ICMP methods

  • Add a note hereTCP SYN scanning

  • Add a note hereUDP scanning (two methods)

  • Add a note here Simple HTML report generation

  • Add a note hereSource port scanning

  • Add a note hereFast hostname resolving

  • Add a note hereExtensive banner grabbing

  • Add a note hereMassive built-in port list description database

  • Add a note hereIP and port scan order randomization

  • Add a note hereA selection of useful tools (ping, traceroute, Whois, and so on)

  • Add a note hereExtensive Windows host enumeration capability

Add a note here Figure 1-19 shows a screen capture of SuperScan results.

Click to collapse
Add a note hereFigure 1-19: SuperScan 4.0

Note

Add a note hereVisit http://www.remote-exploit.org/backtrack.html to download Backtrack 3, released in June 2008. Backtrack 3, a live CD, is packed with more than 300 security tools to test and secure your network.

Add a note here Disaster Recovery and Business Continuity Planning

Add a note hereBusiness continuity planning and disaster recovery procedures address the continuing operations of an organization in the event of a disaster or prolonged service interruption that affects the mission of the organization. Such plans should address an emergency response phase, a recovery phase, and a return to normal operation phase. You should identify the responsibilities of personnel and the available resources during an incident. In reality, contingency and disaster recovery plans do not address every possible scenario or assumption. Rather, they focus on the events most likely to occur and identify an acceptable method of recovery. Periodically, you should exercise the plans and procedures to ensure that they are effective and well understood.

Add a note hereBusiness continuity planning provides a short- to medium-term framework to continue the organizational operations. The following are objectives of business continuity planning:

  • Add a note hereMoving or relocating critical business components and people to a remote location while the original location is being repaired

  • Add a note hereUsing different channels of communication to deal with customers, shareholders, and partners until operations return to normal

Add a note hereDisaster recovery is the process of regaining access to the data, hardware, and software necessary to resume critical business operations after a natural or human-induced disaster. A disaster recovery plan should also include plans for coping with the unexpected or sudden loss of key personnel. A disaster recovery plan is part of a larger process known as business continuity planning.

Add a note hereAfter the events of September 11, 2001, when many companies lost irreplaceable data, the effort put into protecting that data has changed. It is believed that some companies spend up to 25 percent of their IT budget on disaster recovery planning to avoid larger losses. Research indicates that of companies that had a major loss of computerized records, 43 percent never reopen, 51 percent close within two years, and only 6 percent survive long term.

Add a note here Not all disruptions to business operations are equal. Whether the disruption is natural or human, intentional or unintentional, the effect is the same. A good disaster recovery plan takes into account the magnitude of the disruption, recognizing that there are differences between catastrophes, disasters, and nondisasters. In each case, a disruption occurs, but the scale of that disruption can dramatically differ.


Key Topic
  • Add a note here Nondisaster: A situation where a business process is unavailable for a given period of time

  • Add a note here Disaster: A situation that makes a facility unusable for an entire day or more

  • Add a note here Catastrophe: A situation that destroys the facility

Add a note hereGenerally, a nondisaster is a situation in which business operations are interrupted for a relatively short period of time. Disasters cause interruptions of at least a day, sometimes longer. The significant detail in a disaster is that the facilities are not 100 percent destroyed. In a catastrophe, the facilities are destroyed, and all operations must be moved.

Add a note hereThe only way to deal with destruction is redundancy. When a component is destroyed, it must be replaced with a redundant component. When service is disrupted, it must be insured with a service level agreement (SLA) wherein some compensation is acquired for the disruption in service. And when a facility is destroyed, there must be a redundant facility. Without redundancy, it is impossible to recover from destruction.

Add a note hereRedundant facilities are referred to as hot, warm, and cold sites. Each of these is available for a different price, with different resulting downtimes.

Add a note hereIn the case of a hot site, a completely redundant facility is acquired with almost identical equipment. The copying of data to this redundant facility is part of normal operations, so that in the case of a catastrophe, only the latest changes of data must be applied so that full operations are restored. With enough money spent in preparation for a catastrophe, this recovery can take as little as a few minutes or even seconds.


Tip

Add a note hereOrganizations that need to respond in seconds often employ global load balancing (GLB) and distributed storage-area networks (SAN) to respond quickly.

Add a note hereWarm sites are physically redundant facilities without the software and data standing by. Overnight replication would not occur in these instances, necessitating a disaster recovery team to physically go to the redundant facility and bring it up. Depending on how much software and how much data is involved, it can take days to resume operations.

Add a note hereA cold site is usually an empty data center with racks, power, WAN links, and heating, ventilation, and air conditioning (HVAC) already present, but no equipment. In this case, an organization would have to first acquire routers, switches, firewalls, servers, and so on to rebuild everything. Once you restore the backups to the new machines, operations can continue. This option is the least expensive in terms of money spent annually, but would usually take weeks to resume full operations.


Understanding and Developing a Comprehensive Network Security Policy

Add a note here It is important to know that the security policy developed in your organization drives all the steps taken to secure network resources. The development of a comprehensive security policy prepares you for the rest of this course.

Add a note hereTo create an effective security policy, it is necessary to also do a risk analysis to maximize the effectiveness of the policy. Also, it is essential that everyone be aware of the policy; otherwise, it is doomed to fail.

Add a note here Security Policy Overview

Add a note hereEvery organization has something that someone else wants. Someone might want that something for himself, or he might want the satisfaction of denying something to its rightful owner. Your assets are what need the protection of a security policy.

Add a note hereDetermine what your assets are by asking (and answering) the following questions:

  • Add a note hereWhat do you have that others want?

  • Add a note hereWhat processes, data, or information systems are critical to you, your company, or your organization?

  • Add a note hereWhat would stop your company or organization from doing business or fulfilling its mission?

Add a note hereThe answers identify assets ranging from critical databases, vital applications, vital company customer and employee information, classified commercial information, shared drives, email servers, and web servers.

Add a note hereA security policy is a set of objectives for the company, rules of behavior for users and administrators, and requirements for system and management that collectively ensure the security of network and computer systems in an organization. A security policy is a “living document,” meaning that the document is never finished and is continuously updated as technology and employee requirements change.

Add a note hereThe security policy translates, clarifies, and communicates the management position on security as defined in high-level security principles. The security policies act as a bridge between these management objectives and specific security requirements. The security policy informs users, staff, and managers of their obligatory requirements for protecting technology and information assets. The security policy should specify the mechanisms that you need to meet these requirements. The security policy also provides a baseline from which to acquire, configure, and audit computer systems and networks for compliance with the security policy. Therefore, an attempt to use a set of security tools in the absence of at least an implied security policy is meaningless.


Key Topic

Add a note hereThe three reasons for having a security policy are as follows:

  • Add a note hereTo inform users, staff, and managers

  • Add a note hereTo specify mechanisms for security

  • Add a note hereTo provide a baseline

Add a note hereOne of the most common security policy components is an acceptable use policy (AUP). This component defines what users are allowed and not allowed to do on the various components of the system, including the type of traffic that is allowed on the networks. The AUP should be as explicit as possible to avoid ambiguity or misunderstanding. For example, an AUP might list the prohibited website categories.


Note

Add a note hereSome sites refer to an acceptable use policy as an appropriate use policy.

Add a note hereThe audience for the security policy should be anyone who might have access to your network, including employees, contractors, suppliers, and customers. However, the security policy should treat each of these groups differently.

Add a note hereThe audience determines the content of the policy. For example, you probably do not need to include a description of why something is necessary in a policy that is intended for the technical staff. You can assume that the technical staff already knows why a particular requirement is included. Managers are also not likely to be interested in the technical aspects of why a particular requirement is needed. However, they might want the high-level overview or the principles supporting the requirement. When end users know why a particular security control has been included, they are more likely to comply with the policy.

Add a note hereOne document will not likely meet the needs of the entire audience of a large organization. The goal is to ensure that the information security policy documents are coherent with its audience needs.

Add a note here Security Policy Components

Add a note here Figure 1-20 shows the hierarchy of a corporate policy structure that is aimed at effectively meeting the needs of all audiences.

Image from book
Add a note hereFigure 1-20: Components of a Comprehensive Security Policy

Add a note here Most corporations should use a suite of policy documents to meet their wide and varied needs:

  • Add a note here Governing policy: This policy is a high-level treatment of security concepts that are important to the company. Managers and technical custodians are the intended audience. The governing policy controls all security-related interaction among business units and supporting departments in the company. In terms of detail, the governing policy answers the “what” security policy questions.

  • Add a note here End-user policies: This document covers all security topics important to end users. In terms of detail level, end-user policies answer the “what,” “who,” “when,” and “where” security policy questions at an appropriate level of detail for an end user.

  • Add a note here Technical policies: Security staff members use technical policies as they carry out their security responsibilities for the system. These policies are more detailed than the governing policy and are system or issue specific (for example, access control or physical security issues). In terms of detail, technical policies answer the “what,” the “who,” the “when,” and the “where” security policy questions. The “why” is left to the owner of the information.


Note

Add a note hereCisco has created a tool to help you create customized security policies for your organization. Visit http://www.ciscowebtools.com/spb/ to find out more about Cisco Security Policy Builder.

Add a note hereAlso, consider SANS security policies repository at http://www.sans.org/resources/policies.

Governing Policy

Add a note hereThe governing policy outlines the security concepts that are important to the company for managers and technical custodians:

  • Add a note hereThe governing policy controls all security-related interactions among business units and supporting departments in the company.

  • Add a note hereThe governing policy aligns closely with existing company policies, especially human resource policies, but also any other policy that mentions security-related issues such as email, computer use, or related IT subjects.

  • Add a note hereThe governing policy is placed at the same level as all companywide policies.

  • Add a note hereThe governing policy supports the technical and end-user policies.

Add a note hereA governing policy includes the following key components:

  • Add a note hereA statement of the issue that the policy addresses

  • Add a note hereA statement about your position as IT manager on the policy

  • Add a note hereHow the policy applies in the environment

  • Add a note hereThe roles and responsibilities of those affected by the policy

  • Add a note hereWhat level of compliance to the policy is necessary

  • Add a note here Which actions, activities, and processes are allowed and which are not

  • Add a note hereWhat the consequences of noncompliance are

End-User Policies

Add a note hereThe end-user policy is a single policy document that covers all the policy topics pertaining to information security that end users should know about, comply with, and implement. This policy may overlap with the technical policies and is at the same level as a technical policy. Grouping all the end-user policies together means that users have to go to only one place and read one document to learn everything that they need to do to ensure compliance with the company security policy.

Technical Policies

Add a note hereSecurity staff members use the technical policies in the conduct of their daily security responsibilities. These policies are more detailed than the governing policy and are system or issue specific (for example, router security or physical security issues). These policies are essentially security handbooks that describe what the security staff does, but not how the security staff performs its functions.

Add a note hereThe following are typical policy categories for technical policies:

  • Add a note here General policies

    • Add a note here AUP: Defines the acceptable use of equipment and computing services, and the appropriate security measures that employees should take to protect the corporate resources and proprietary information.

    • Add a note here Account access request policy: Formalizes the account and access request process within the organization. Users and system administrators who bypass the standard processes for account and access requests can cause legal action against the organization.

    • Add a note here Acquisition assessment policy: Defines the responsibilities regarding corporate acquisitions and defines the minimum requirements that the information security group must complete for an acquisition assessment.

    • Add a note here Audit policy: Conducts audits and risk assessments to ensure integrity of information and resources, investigates incidents, ensures conformance to security policies, or monitors user and system activity where appropriate.

    • Add a note here Information sensitivity policy: Defines the requirements for classifying and securing information in a manner appropriate to its sensitivity level.

    • Add a note here Password policy: Defines the standards for creating, protecting, and changing strong passwords.

    • Add a note here Risk-assessment policy: Defines the requirements and provides the authority for the information security team to identify, assess, and remediate risks to the information infrastructure that is associated with conducting business.

    • Add a note here Global web server policy: Defines the standards that are required by all web hosts.

  • Add a note here Email policies

    • Add a note here Automatically forwarded email policy: Documents the policy restricting automatic email forwarding to an external destination without prior approval from the appropriate manager or director.

    • Add a note here Email policy: Defines the standards to prevent tarnishing the public image of the organization.

    • Add a note here Spam policy: The AUP covers spam.

  • Add a note here Remote-access policies

    • Add a note here Dial-in access policy: Defines the appropriate dial-in access and its use by authorized personnel.

    • Add a note here Remote-access policy: Defines the standards for connecting to the organization network from any host or network external to the organization.

    • Add a note here VPN security policy: Defines the requirements for remote-access IP Security (IPsec) or Layer 2 Tunneling Protocol (L2TP) VPN connections to the organization network.

  • Add a note here Telephony policies

    • Add a note here Analog and ISDN line policy: Defines the standards to use analog and ISDN lines for sending and receiving faxes and for connection to computers.

    • Add a note here Personal communication device policy: Defines the information security’s requirements for personal communication devices, such as voicemail, IP phones, softphones, and so on.

  • Add a note here Application policies

    • Add a note here Acceptable encryption policy: Defines the requirements for encryption algorithms that are used within the organization.

    • Add a note here Application service provider (ASP) policy: Defines the minimum security criteria that an ASP must execute before the organization uses them on a project.

    • Add a note here Database credentials coding policy: Defines the requirements for securely storing and retrieving database usernames and passwords.

    • Add a note here Interprocess communications policy: Defines the security requirements that any two or more processes must meet when they communicate with each other using a network socket or operating system socket.

    • Add a note here Project security policy: Defines requirements for project managers to review all projects for possible security requirements.

    • Add a note here Source code protection policy: Establishes minimum information security requirements for managing product source code.

  • Add a note here Network policies

    • Add a note here Extranet policy: Defines the requirement that third-party organizations that need access to the organization networks must sign a third-party connection agreement.

    • Add a note here Minimum requirements for network access policy: Defines the standards and requirements for any device that requires connectivity to the internal network.

    • Add a note here Network access standards: Defines the standards for secure physical port access for all wired and wireless network data ports.

    • Add a note here Router and switch security policy: Defines the minimal security configuration standards for routers and switches inside a company production network or used in a production capacity.

    • Add a note here Server security policy: Defines the minimal security configuration standards for servers inside a company production network or used in a production capacity.

  • Add a note here Wireless communication policy: Defines standards for wireless systems that are used to connect to the organization networks.

  • Add a note here Document Retention policy: Defines the minimal systematic review, retention, and destruction of documents received or created during the course of business. The categories of retention policy are, among others:

    • Add a note here Electronic communication retention policy: Defines standards for the retention of email and instant messaging.

    • Add a note here Financial retention policy: Defines standards for the retention of bank statements, annual reports, pay records, accounts payable and receivable, and so on.

    • Add a note here Employee records retention policy: Defines standards for the retention of employee personal records.

    • Add a note here Operation records retention policy: Defines standards for the retention of past inventories information, training manuals, suppliers lists, and so forth.

Add a note here Standards, Guidelines, and Procedures

Add a note hereSecurity policies establish a framework within to work, but they are excessively general to be of much use to individuals responsible for implementing these policies. Because of this, other more detailed documents exist. Among the more important detailed documents are the standards, guidelines, and procedures documents.

Add a note hereWhereas policy documents are very much high-level overview documents, the standards, guidelines, and procedure documents are documents that the security staff will use regularly to implement the security policies.

Standards

Add a note hereStandards allow an IT staff to be consistent. They specify the use of specific technologies because no one can know everything. Standards also try to provide consistency in the network because it is unreasonable to support multiple versions of hardware and software unless it is necessary. The most successful IT organizations have standards to improve efficiency and to keep things as simple as possible.

Add a note hereStandardization also applies to security. One of the most important security principles is consistency. If you support 100 routers, it is important that you configure all 100 routers as similarly as possible. If you do not do this, it is difficult to maintain security. When you do not strive for the simplest of solutions, you usually fail in being secure.

Guidelines

Add a note here Guidelines help provide a list of suggestions on how you can do things better. Guidelines are similar to standards, but are more flexible and are not usually mandatory. You will find some of the best guidelines available in repositories known as “best practices.” The following is a list of widely available guidelines:

  • Add a note hereNational Institute of Standards and Technology (NIST) Computer Security Resource Center

  • Add a note hereNational Security Agency (NSA) Security Configuration Guides

  • Add a note hereThe Common Criteria Standard

  • Add a note hereRainbow Series

Procedures

Add a note hereProcedure documents are longer and more detailed than the standards and guidelines documents. Procedure documents include the details of implementation, usually with step-by-step instructions and graphics. Procedure documents are extremely important for large organizations to have the consistency of deployment that is necessary to have a secure environment. Inconsistency is the enemy of security.

Add a note here Security Policy Roles and Responsibilities

Add a note hereIn any organization, it is senior management, such as the CEO, which is always ultimately responsible for everything. Typically, senior management only oversees the development of a security policy. The creation and maintenance of a security policy is usually delegated to the people in charge of IT or security operations.

Add a note hereSometimes the senior security or IT management personnel, such as the chief security officer (CSO), the chief information officer (CIO), or the chief information security officer (CISO), will have the expertise to create the policy, sometimes they will delegate it, and sometimes it will be a bit of both strategies. But the senior security person is always intimately involved in the development and maintenance of security policy. Guidelines can provide a framework for policy decision making.

Add a note hereSenior security staff is often consulted for input on a proposed policy project. They might even be responsible for the development and maintenance of portions of the policy. It is more likely that senior staff will be responsible for the development of standards and procedures.

Add a note hereEveryone else who is involved in the security policy has the duty to abide by it. Many of the policy statements will include language that refers to a potential loss of employment for violation of the policy. IT staff and end users alike are responsible to know the policy and follow it.

Add a note here Risk Analysis and Management

Add a note here Every process of security should first address the following questions:

  • Add a note hereWhich are the threats the system is facing?

  • Add a note hereWhich are the probable threats and what would be their consequence, if exploited?

Add a note hereThe threat-identification process provides an organization with a list of threats, which a system is subject to in a particular environment.


Note

Add a note hereAn interesting method of modeling security threats is the Attack Trees method by Bruce Schneier. You can find more information about this method at http://en.wikipedia.org/wiki/Attack_tree.

Add a note hereRisk analysis is a process that estimates the probability and severity of threats that a system needing protection faces. Risk analysis provides an organization with a prioritized list of risks, which the organization must mitigate, and allows an organization to focus on the most important threats first.

Risk Analysis

Add a note hereRisk analysis is the systematic study of uncertainties and risks. Risk analysts seek to identify the risks that a company faces, understand how and when they arise, and estimate the impact (financial or otherwise) of adverse outcomes. Risk managers start with risk analysis, and then seek to take actions that will mitigate these risks.

Add a note hereTwo types of risk analysis are of interest in information security:

  • Add a note here Quantitative: Quantitative risk analysis uses a mathematical model that puts numbers to the value of assets, the cost of threats being realized, and so on. Quantitative risk analysis provides an actual monetary figure of expected losses, which is typically based on an annual cost. You can then use this number to justify proposed countermeasures. For example, if you can establish that you will lose $1,000,000 by doing nothing, you can justify spending $300,000 to reduce that risk by 50 percent to 75 percent.

  • Add a note here Qualitative: Qualitative risk analysis uses a scenario model. This approach is best for large cities, states, and countries to use because it is impractical to try to list all the assets, which is the starting point for any quantitative risk analysis. By the time a typical national government lists all of its assets, the list would have hundreds or thousands of changes and would no longer be accurate.

Quantitative Risk-Analysis Formula

Add a note hereQuantitative analysis relies on specific formulas to determine the value of the risk decision variables. These include formulas that calculate the asset value (AV), exposure factor (EF), single loss expectancy (SLE), annualized rate of occurrence (ARO), and annualized loss expectancy (ALE). The ALE formula is as follows:

Add a note here The AV is the value of an asset. This would include the purchase price, the cost of deployment, and the cost of maintenance. In the case of a database or a web server, the AV should also include the cost of development. AV is not an easy number to calculate.

Add a note hereThe EF is an estimate of the degree of destruction that will occur. For example, suppose that you consider flood a threat. Could it destroy our data center? Would the destruction be 60 percent, 80 percent, or 100 percent? The risk-assessment team would have to make a determination that evaluates everything possible, and then make a judgment call. For this example, assume that a flood will have a 60 percent destruction factor, because you store a backup copy of all media and data offsite. Your only losses would be the hardware and productivity.

Add a note hereAs another example, consider data entry errors, which are much less damaging than a flood. A single data entry error would hardly be more than a fraction of a percent in exposure. The exposure factor of a data entry error might be as small as .001 percent.


Caution

Add a note hereOne of the ironies of risk analysis is how much estimating (guessing) is involved.

Add a note hereThe SLE calculation is a number that represents the expected loss from a single occurrence of the threat. The SLE is defined as the AV * EF.

Add a note hereTo use our previous examples, you would come up with the following results for the SLE calculations:

  • Add a note here Flood threat

    Add a note hereExposure factor: 60 percent

    Add a note hereAV of the enterprise: US$10,000,000

    Add a note here$10,000,000 * .60 = $6,000,000

  • Add a note here Data entry error

    Add a note hereExposure factor: .001 percent

    Add a note hereAV of data and databases: $1,000,000

    Add a note here$1,000,000 * .000001 = $10 SLE

Add a note hereThe ARO is a value that estimates the frequency of an event and is used to calculate the ALE.

Add a note hereContinuing the preceding example, the type of flood that you expect could reach your data center would be a “flood of the century” type of event. Therefore, you give it a 1/100 chance of occurring this year, making the ARO for the flood 1/100.

Add a note hereFurthermore, you expect the data entry error to occur 500 times a day. Because the organization is open for business 250 days per year, you estimate the ARO for the data entry error to be 500 * 250, or 125,000 times.

Add a note hereRisk analysts calculate the ALE in annualized terms to address the cost to the organization if the organization does nothing to counter existing threats. The ALE is derived from multiplying the SLE by the ARO. The following ALE calculations continue with the two previous examples.

  • Add a note here Flood threat

    Add a note hereSLE: $6,000,000

    Add a note hereARO: .01

    Add a note here$6,000,000 * .01 = $60,000 ALE

  • Add a note here Data input error

    Add a note hereSLE: $10

    Add a note hereAROL: 125,000

    Add a note here$10 * 125,000 = $1,250,000 ALE

Add a note hereA decision to spend $50,000 to enhance the security of our database applications to reduce data entry errors by 90 percent is now an easy decision. It is equally easy to reject a proposal to enhance our defenses against floods that costs $3,000,000.

Add a note hereWhen you perform a quantitative risk analysis, you will identify clear costs as long as the existing conditions remain the same. There is a list of expected issues, the relative cost of those events, and the total cost if all expected threats are realized. These numbers are put in to annual terms to coincide with the annual budgets of most organizations.

Add a note hereYou then use these numbers in decision making. If an organization had a list of 10 expected threats, it could then prioritize the threats and address the most serious threats first. This prioritization enables management to focus their resources where it will do the most good.

Add a note hereFor example, suppose an organization has the following list of threats and costs because of a quantitative risk analysis:

  • Add a note here Insider network abuse: $1,000,000 in lost productivity

  • Add a note here Data input error: $500,000

  • Add a note here Worm outbreak: $100,000

  • Add a note here Viruses: $10,000

  • Add a note here Laptop theft: $10,000

Add a note hereDecision makers could easily decide that it is of greatest benefit to address insider network abuse and leave the antivirus solution alone. They could also find it easy to support a $200,000 URL filtering solution to address insider network abuse and reject a $40,000 solution designed to enhance laptop safety. Without these numbers from a risk analysis, the decisions made would likely differ.


Tip

Add a note hereIn cases that involve national security, it is not advisable to base decisions on cost.

Add a note here Table 1-2 provides an example of threat identification for connecting an e-banking system to the Internet. It enumerates the following threats to the system, and the probability and severity of the impact on the bank should the threat materialize. The list of potential threats is by no means comprehensive, but includes the most obvious ones.

Add a note here Table 1-2: List of Potential Threats and Their Impact
Open table as spreadsheet

Add a note hereThreat

Add a note hereDescription

Add a note hereSeverity

Add a note hereInternal system compromise

Add a note hereThe attacker could use the exposed e-banking servers to break into an internal bank system, causing substantial damage.

Add a note hereExtremely severe and likely, if untrusted software is used to pass data to the inside network.

Add a note hereStolen customer data from an external server

Add a note hereThe attacker could, by breaking into the exposed application server, steal all, or a substantial amount of, personal and financial data of the bank customers from the customer database.

Add a note hereSevere and likely, if the external server is vulnerable to intrusions, which could compromise the operating system or the application.

Add a note herePhony transactions from an external server

Add a note hereThe attacker could, by breaking into the external server, alter the code of the e-banking application, and run arbitrary transactions impersonating any legitimate user.

Add a note hereSevere and likely, if the external server is vulnerable to intrusions, which could compromise the operating system or the application.

Add a note herePhony transactions if the customer PIN or smart card is stolen

Add a note hereThe attacker could steal the identity of a customer and run malicious transactions from the compromised account.

Add a note hereLimited severity, because individual accounts are compromised; likely only if the stolen credentials are not detected quickly.

Add a note hereInsider attack on the system

Add a note hereA bank employee might find a flaw in the system to mount an attack.

Add a note hereExtremely severe and likely, because the bank has had its share of insider attacks on company data.

Add a note hereDoS attacks

Add a note hereDoS attacks could interrupt the service, because the attacker might compromise the availability of the application, cutting off legitimate users and potentially causing a public relations nightmare.

Add a note hereSevere and likely, because tools to perform such attacks are easy to find, and defense against such attacks is limited.

Add a note hereAll the threats in Table 1-2 can lead to loss of reputation and customer trust.

Add a note hereAfter you identify threats and assess the risks, you must deploy a protection strategy to protect against the risks. There are two very different methods to handle risks:

  • Add a note here Risk management: This method uses the deployment of protection mechanisms to reduce risks to acceptable levels. Risk management is perhaps the most basic and the most difficult aspect of building secure systems, because it requires good knowledge of risks, risk environments, and mitigation methods.

  • Add a note here Risk avoidance: This method eliminates risk by avoiding the threats altogether, which is usually not an option in the commercial world, where controlled (managed) risk enables profits.

Risk Management

Add a note hereContinuing the example of a bank that wants to provide e-banking services and has identified threats and performed a risk analysis, risk management can be illustrated by high-level strategy decisions, which describe how to mitigate each risk to an acceptable level. Table 1-3 provides a list of the threats, the associated risk analysis, and the risk mitigation.

Add a note here Table 1-3: List of Threats, Risk Analysis, and Risk Mitigation
Open table as spreadsheet

Add a note hereThreat

Add a note hereRisk Analysis

Add a note hereRisk Mitigation

Add a note hereInternal system compromise

Add a note hereExtremely severe and likely, if untrusted software is used to pass data to the inside network

Add a note hereProvide the least amount of privilege access possible to the inside, and utilize a secure multitiered application which minimizes inside access

Add a note hereStolen customer data from an external server

Add a note hereSevere and likely, if the external server is vulnerable to intrusions, which could compromise the operating system or the application

Add a note hereKeep all the customer data on inside servers, and only transfer data to the outside on demand

Add a note herePhony transactions from an external server

Add a note hereSevere and likely, if the external server is vulnerable to intrusions, which could compromise the operating system or the application

Add a note hereDesign the external server application so that it does not allow arbitrary transactions to be called for any customer account

Add a note herePhony transactions if the customer PIN or smart card is stolen

Add a note hereLimited severity, because only individual accounts are compromised; likely only if the stolen credentials are not detected quickly

Add a note hereUse a quick refresh of revocation lists and have a contract with the user which forces the user to assume responsibility for stolen token cards

Add a note hereInsider attack on the system

Add a note hereExtremely severe and likely, because the bank has had its share of insider attacks on company data

Add a note hereStrictly limit inside access to the application and provide strict auditing of all accesses from the inside

Add a note hereDoS attacks

Add a note hereSevere and likely, because tools to perform such attacks are easy to find, and defense against such attacks is limited

Add a note hereProvide high-performance connectivity to the Internet, deploy of quality of service (QoS), implement high availability by using multiple Internet connections, and protect the server by hardening and implementing firewall DoS defense methods

Add a note here Using the risk-avoidance approach, the company would decide not to offer the e-banking service at all because they deem it too risky. Such an attitude might be valid for most military organizations, but is usually not an option in the commercial world. Organizations that can manage the risks, and not avoid them, are traditionally the most profitable.

Add a note hereA different way of thinking about security might be this: “If we can figure out a way to provide a service securely, we will earn a lot of money.” This attitude moves away from the paranoid thinking of many risk analysts, who might try to find a reason not to deploy a certain service. Sometimes it can help to take a fresh look at what risk management is all about.

Add a note here Principles of Secure Network Design

Add a note here Business goals and risk analysis drive the need for network security. Regardless of the security implications, business needs must come first. If your business cannot function because of security concerns, you have a problem. The security system design must accommodate the goals of the business, not hinder them. Risk analysis includes two key elements:

  • Add a note hereWhat does the cost-benefit analysis of your security system tell you?

  • Add a note hereHow will the latest attack techniques play out in your network environment?

Add a note here Figure 1-22 illustrates the key factors you should consider when designing a secure network:

  • Add a note here Business needs: What does your organization want to do with the network?

  • Add a note here Risk analysis: What is the risk and cost balance?

  • Add a note here Security policy: What are the policies, standards, and guidelines that you need to address business needs and risks?

  • Add a note here Industry best practices: What are the reliable, well-understood, and recommended security best practices?

  • Add a note here Security operations: These operations include incident response, monitoring, maintenance, and auditing the system for compliance.

Image from book
Add a note hereFigure 1-22: Factors Affecting the Design of a Secure Network

Realistic Assumptions

Add a note hereHistorically, a huge percentage of security mechanisms are broken, misconfigured, or bypassed because the designer or implementer made unfounded assumptions about how and where the system will be used; for example, wrong assumptions were made about the users of the system, the attackers and threats, and the technology that is used to build the system.

Add a note hereA wrong assumption ends up being used as a bad axiom in all further design work; it might influence one design decision, and then propagate to other decisions that might depend on it. Wrong decisions are especially dangerous in early stages of secure system design, when threats are modeled and when risks are assessed. It is often easy to correct or enhance an implementation aspect of a system; however, design errors are either extremely hard or impossible to correct without substantial investments in time and technology.

Add a note hereThe following is a summary of recommendations you should follow to avoid making wrong assumptions:

  • Add a note hereFirst, expect that any aspect of a system might fail, and evaluate how this failure affects the security of a system. It is possible for every single element of a system to fail; only the probability of failure might differ for different elements. When designing a system, perform “what-if” analysis for failures of every element, assess the probability of failure, and analyze all possible consequences of an element failure, taking into account consequent cascading failures of other elements.

  • Add a note hereAs a part of the “anything can fail” mindset, identify any elements that “fail open.” Fail open occurs when a failure results in a complete bypass of the security function of the element. Ideally, any security element should be fail-safe; if the element fails, it should default to a secure state, such as blocking all traffic across it.

  • Add a note here Try to identify all attack possibilities. The Attack Tree method is one successful method of top-down analysis of possible system failures, which involves evaluating the simplicity and probability of every attack.

  • Add a note hereRealistically evaluate the probability of exploitation. An often-encountered philosophy is “if there is no exploit code available for a particular vulnerability, no one will be able to exploit it.” This philosophy is true only for script kiddie attacks, and a sounder stance must be taken, such as “if a vulnerability exists, any skilled and focused attacker will easily write a tool to exploit it.” The focus should be on the resources needed to create an attack tool, not on the obscurity of the vulnerability.

  • Add a note hereAlways account for technological advances if an attack is currently unlikely because the attacker needs many resources. As computer power increases, the probability of attacks might increase with an alarming rate. Many systems have been compromised because of unrealistic assumptions about how much computing power was necessary to mount successful attacks (the recommended lengths of cryptographic keys are a prime example).

  • Add a note hereAssume that people will make mistakes. For example, end users might use a system improperly, compromising its security unintentionally. Likewise, attackers will not use common and well-established techniques to compromise a system; they might hammer the system with seemingly random attacks, looking for possible information on how the system behaves under unexpected conditions.

  • Add a note hereAlways check your assumptions with other people, who might have a fresh perspective on potential threats and their probability. The more people who question your assumptions, the more likely you can identify a bad assumption.

Incorrect Assumptions: Cautionary Tales

Add a note hereThree examples of wrong assumptions come from areas not directly related to network security.

Add a note hereThe encryption of DVD movies, which uses a weak algorithm called Content Scrambling System (CSS), is an example of bad assumptions made about the scope of system use. The original assumption was that DVDs would be played only on hardware players, where the decryption keys could be stored in a tamper-resistant chip inside the player, making it extremely hard for even skilled attackers to compromise the DVDs. However, when software DVD players appeared, the DVDs were quickly reverse engineered, because making software tamper resistant is next to impossible against a determined attacker. The keys were recovered from one of the well-known players, and an algorithm was published on the Internet, together with the keys.

Add a note hereThe response strategy of the DVD industry was to try to ban the publishing of the CSS algorithm and keys, but the decision of the court that the CSS algorithm source code was essentially free speech stopped much of their efforts.

Add a note hereAnother example of a wrong or poor assumption was the lack of encryption of U.S. cellular traffic. When cellular phones were first introduced, the assumption was that scanners, which could intercept cellular traffic, were too expensive to mount any large-scale attacks against call confidentiality in cellular networks. In a couple of years, the price of these scanners dropped to the point that the scanners were available to almost anyone. Thus, bad assumptions compromised the protection policy of the cellular network.

Add a note hereThe next-generation U.S. cellular service uses digital transmission, but the same assumption was made, that digital scanners are too expensive. As technology advances, the same story has unfolded for the digital transmissions.

Concept of Least Privilege

Add a note hereThe least privilege concept is a philosophy in which each subject, user, program, host, and so on should have only the minimum necessary privileges to perform a certain task.

Add a note hereThe rationale behind the concept is that having too many privileges for a task can result in doing more damage than would be otherwise possible, whether the damage is intentional or unintentional. Using the least privileges always narrows down the window of vulnerability, because it reduces the number of possible side effects of a task. Least privilege also simplifies a system when you analyze it for possible flaws, because if you allow only a very limited number of prescribed actions and system states, the potential for unwanted interactions within a system is limited.

Add a note hereIn practice, the least privilege concept is often not followed, because a person or process must perform multiple tasks that require different privileges. Because the configuration of privileges in such an environment is often cumbersome, a person or process is given high (or even worse, the highest possible) privileges, which automatically enables them to perform a variety of tasks, including the tasks originally required. This configuration of privileges opens up a system to additional threats and interactions, which might not be expected.

Add a note here Figure 1-23 shows an example of proper least privilege enforcement. A web server is located inside a firewall system and must be accessed by inside and outside users. No other access to the system is necessary, and the system does not need to open any connections itself (it is a simple static web server).

Click to collapse
Add a note hereFigure 1-23: Least Privilege Example

Add a note hereIn Figure 1-23, the firewall is configured to permit only HTTP connectivity to the server from the inside interface to the outside interface. The firewall denies all other connections to the server because they are not necessary. Also, the firewall prevents the web server from sourcing any connections because they are not required. An attacker who compromises the web server would be isolated on it because no connectivity is allowed from the web server.

Add a note hereIn such a situation, many organizations would permit all access to the web server from the inside. This level of access opens up the server for insider attacks, or enables an attacker who manages to enter the protected network to also attack any service running on the web server.

Add a note hereYou can see another example of least privilege enforcement by looking at the web server host itself. The host runs an exposed web server program, which is expected to be attacked by external crackers. Therefore, the web server program must be protected, and at the same time, other processes and data on the host must be protected from the attacker, who can potentially compromise the web server program. To protect the rest of the operating system, you can use several well-known techniques, all of which implement the least privilege concept:

  • Add a note hereRun the web server program under a special username, which has minimal rights in the host operating system (it can listen on port 80 and it can access its data on disk).

  • Add a note hereSet the file permissions in such a way that the web server program can access only its executable code (which is not owned by it, so it cannot be changed by it) and the documents it is serving (HTML, multimedia files).

  • Add a note hereConfigure the operating system to limit the web server program to be a part of the file system, disallowing it access to any other directories (for example, using the UNIX chroot system call).

Concept of Simplicity

Add a note hereComplexity is one of the biggest enemies of security. Complexity makes it hard for the designer or implementer to predict how parts of the system will interact, and makes the system extremely difficult to analyze from the security perspective. Simplicity of design and implementation should therefore be one of the main goals of the designer.

Add a note hereWhen you must implement a security mechanism, it is always recommended to use the simplest possible solution, which still provides an adequate level of security. When you need to put a very complex mechanism in place, consider replacing it with multiple simpler and easier-to-verify mechanisms, as long as the resulting protection strength is comparable to the original idea.

Add a note hereAlso, simplicity is beneficial for the end users of the system. If the end user does not understand the system adequately, the system can be compromised through unintentional misuse. It is important to note that end users do not need to be aware of the internal workings of the system, but the usage instructions should be simple and concise, as far as security is concerned.

Add a note hereYou can find an example of design and implementation simplicity in the formulation of a user security policy.

Add a note here Two ways to formulate the same security policy that relates to the end-user responsibilities are as follows:

  • Add a note here Complex rule: All end users will participate in risk mitigation by enforcing discretionary access control on file system objects in such a way as to prevent external subjects from violating the integrity of the properties or contents of an object.

  • Add a note here Simple rule: When changing file permissions, ensure that only Cisco employees will have “write” access to that file.

Add a note hereAn overly technical, confusing formulation alienates users, whereas a simple and concise formulation enables the user to easily comprehend the required procedures and understand why such protection must be put in place.

Add a note hereIn short, simplicity in design often makes the implementation of security simpler.

Add a note hereYou can also achieve simplicity by intentionally removing functionality from existing systems. This concept introduces the well-known practice of disabling all unnecessary services that a system offers. Disabling these services removes many potential attack possibilities. You could identify this as the enforcement of least privilege (running only the minimal necessary set of services), and it makes the system easier to analyze.

Add a note hereAnother way to simplify security is to help simplify end-user functions. For example, if email needs to be encrypted when it goes to external business partners, a solution that would be the simplest for end users is to take the end users out of the equation and use technology to perform automated encryption of the email. A mail gateway can be configured to automatically encrypt all outgoing mail.

Add a note here Security Awareness

Add a note hereTechnical, administrative, and physical controls can all be defeated without the participation of the end-user community. To get accountants and secretaries to think about information security, you must regularly remind staff members about security. The technical staff also needs regular reminders because their jobs tend to emphasize performance rather than secure performance. Therefore, leadership must develop a nonintrusive program that keeps everyone aware of security and how to work together to maintain the security of their data. The three key components used to implement this type of program are awareness, training, and education.

Add a note hereAn effective computer security-awareness and -training program requires proper planning, implementation, maintenance, and periodic evaluation. In general, a computer security-awareness and -training program should encompass the following seven steps:

Add a note here Step 1

Add a note here Identify program scope, goals, and objectives.

Add a note hereThe scope of the program should provide training to all types of people who interact with IT systems. Because users need training that relates directly to their use of particular systems, you need to supplement a large organizationwide program with more system-specific programs.

Add a note here Step 2

Add a note here Identify training staff.

Add a note hereIt is important that trainers have sufficient knowledge of computer security issues, principles, and techniques. It is also vital that they know how to communicate information and ideas effectively.

Add a note here Step 3

Add a note here Identify target audiences.

Add a note hereNot everyone needs the same degree or type of computer security information to do his or her job. A computer security-awareness and -training program that distinguishes between groups of people, presents only the information that is needed by the particular audience, and omits irrelevant information will have the best results.

Add a note here Step 4

Add a note here Motivate management and employees.

Add a note hereTo successfully implement an awareness and training program, it is important to gain the support of management and employees. Consider using motivational techniques to show management and employees how their participation in a computer security and awareness program will benefit the organization.

Add a note here Step 5

Add a note here Administer the program.

Add a note hereSeveral important considerations for administering the program include visibility, selection of appropriate training methods, topics, materials, and presentation techniques.

Add a note here Step 6

Add a note here Maintain the program.

Add a note hereYou should make an effort to keep abreast of changes in computer technology and security requirements. A training program that meets the needs of an organization today may become ineffective when the organization starts to use a new application or changes its environment, such as by connecting to the Internet.

Add a note here Step 7

Add a note here Evaluate the program.

Add a note hereAn evaluation should attempt to ascertain how much information is retained, to what extent computer security procedures are being followed, and the general attitudes toward computer security.

Add a note hereA successful IT security program consists of the following:

  1. Add a note hereDeveloping IT security policy that reflects business needs tempered by known risks

  2. Add a note hereInforming users of their IT security responsibilities, as documented in agency security policy and procedures

  3. Add a note hereEstablishing processes for monitoring and reviewing the program

Add a note hereYou should focus security awareness and training on the entire user population of the organization. Management should set the example for proper IT security behavior within an organization. An awareness program should begin with an effort that you can deploy and implement in various ways and be aimed at all levels of the organization, including senior and executive managers. The effectiveness of this effort usually determines the effectiveness of the awareness and training program and how successful the IT security program will be.

Add a note here An awareness and training program is crucial because it is the vehicle for disseminating information that users, including managers, need to do their jobs. An IT security program is the vehicle that you use to communicate security requirements across the enterprise.

Add a note hereAn effective IT security-awareness and -training program explains proper rules of behavior for the use of the IT systems and information of a company. The program communicates IT security policies and procedures that must be followed. This program must precede and lay the foundation for any sanctions that your company will impose for noncompliance. You should first inform the users of the expectations. You must derive accountability from a fully informed, well-trained, and aware workforce.

Add a note hereSecurity awareness efforts are designed to change behavior or reinforce good security practices. Awareness is defined in NIST Special Publication 800-16 as follows:

Add a note hereAwareness is not training. The purpose of awareness presentations is simply to focus attention on security. Awareness presentations are intended to allow individuals to recognize IT security concerns and respond accordingly. In awareness activities, the learner is the recipient of information, whereas the learner in a training environment has a more active role. Awareness relies on reaching broad audiences with attractive packaging techniques. Training is more formal, having a goal of building knowledge and skills to facilitate the job performance.

Add a note hereAn example of a topic for an awareness session (or awareness material to be distributed) is virus protection. You can briefly address the subject by describing what a virus is, what can happen if a virus infects a user system, what the user should do to protect the system, and what users should do if they discover a virus.

Add a note hereTraining strives to produce relevant and needed security skills and competencies by practitioners of functional specialties other than IT security (for example, management, systems design and development, acquisition, and auditing). The most significant difference between training and awareness is that training tries to teach skills that allow a person to perform a specific function, whereas awareness focuses the attention of an individual on an issue or set of issues. The skills that users acquire during training build on the awareness foundation (in particular, on the security basics and literacy material). A training curriculum does not necessarily lead to a formal degree from an institution of higher learning; however, a training course might contain much of the same material found in a course that a college or university includes in a certificate or degree program.

Add a note hereAn example of training is an IT security course for system administrators, which should address in detail the management controls, operational controls, and technical controls that should be implemented. Management controls include policy, IT security program management, risk management, and life cycle security. Operational controls include personnel and user issues, contingency planning, incident handling, awareness and training, computer support and operations, and physical and environmental security issues. Technical controls include identification and authentication, logical access controls, audit trails, and cryptography.

Add a note here Education integrates all the security skills and competencies of the various functional specialties into a common body of knowledge; adds a multidisciplinary study of concepts, issues, and principles (technological and social); and strives to produce IT security specialists and professionals capable of vision and proactive response.

Add a note hereAn example of education is a degree program at a college or university. Some people take a course or several courses to develop or enhance their skills in a particular discipline. This is training as opposed to education. Many colleges and universities offer certificate programs, wherein a student may take two, six, or eight classes (for example, in a related discipline), and are then awarded a certificate upon completion. Often, these certificate programs are conducted as a joint effort between schools and software or hardware vendors. These programs are more characteristic of training than education. Those responsible for security training must assess both types of programs and decide which one better addresses their identified needs.

Add a note hereA successfully implemented training and awareness program, in conjunction with a good security operations practice, should result in many benefits to an organization. The technical staff should be better at implementing the technical controls. End users, executives, and everyone else should also do a better job of implementing the remaining administrative and physical controls. The resulting more thorough implementation of a well-designed set of controls is guaranteed to increase security.


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