network security essentials chapter 1 fourth edition by william stallings (based on lecture slides...
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Network Security Network Security EssentialsEssentialsChapter 1Chapter 1
Fourth EditionFourth Editionby William Stallingsby William Stallings
(Based on Lecture slides by (Based on Lecture slides by Lawrie Brown)Lawrie Brown)
The art of war teaches us to rely not on the The art of war teaches us to rely not on the likelihood of the enemy's not coming, but likelihood of the enemy's not coming, but on our own readiness to receive him; not on our own readiness to receive him; not on the chance of his not attacking, but on the chance of his not attacking, but rather on the fact that we have made our rather on the fact that we have made our position unassailable. position unassailable. ——The Art of War, The Art of War, Sun TzuSun Tzu
The combination of space, time, and The combination of space, time, and strength that must be considered as the strength that must be considered as the basic elements of this theory of defense basic elements of this theory of defense makes this a fairly complicated matter. makes this a fairly complicated matter. Consequently, it is not easy to find a fixed Consequently, it is not easy to find a fixed point of departurepoint of departure. . — — On War, Carl Von ClausewitzOn War, Carl Von Clausewitz
Computer SecurityComputer Security
The protection afforded to an automated The protection afforded to an automated information system in order to attain the information system in order to attain the applicable objectives of preserving the applicable objectives of preserving the integrityintegrity, , availabilityavailability and and confidentialityconfidentiality of of information system resources (includes information system resources (includes hardware, software, firmware, hardware, software, firmware, information/data, and telecommunications)information/data, and telecommunications)[NIST 1995][NIST 1995]
Key Security ConceptsKey Security Concepts
Three Key Objectives
Confidentiality Data confidentiality Privacy
Integrity Data integrity System integrity
Availability Additional concepts
Authenticity Accountability
Levels of ImpactLevels of Impact
3 levels of impact from a security breach3 levels of impact from a security breach LowLow ModerateModerate HighHigh
Examples of Security Examples of Security RequirementsRequirements
confidentiality – student gradesconfidentiality – student grades integrity – patient informationintegrity – patient information availability – authentication serviceavailability – authentication service
Computer Security ChallengesComputer Security Challenges
1.1. not simplenot simple2.2. must consider potential attacksmust consider potential attacks3.3. procedures used counter-intuitiveprocedures used counter-intuitive4.4. involve algorithms and secret infoinvolve algorithms and secret info5.5. must decide where to deploy mechanismsmust decide where to deploy mechanisms6.6. battle of wits between attacker / adminbattle of wits between attacker / admin7.7. not perceived on benefit until failsnot perceived on benefit until fails8.8. requires regular monitoringrequires regular monitoring9.9. too often an after-thoughttoo often an after-thought10.10. regarded as impediment to using systemregarded as impediment to using system
OSI Security ArchitectureOSI Security Architecture
ITU-T X.800 “Security Architecture for OSI”ITU-T X.800 “Security Architecture for OSI” defines a systematic way of defining and defines a systematic way of defining and
providing security requirementsproviding security requirements for us it provides a useful, if abstract, for us it provides a useful, if abstract,
overview of concepts we will studyoverview of concepts we will study
Aspects of SecurityAspects of Security
3 aspects of information security:3 aspects of information security: security attacksecurity attack security mechanism: detect, prevent, security mechanism: detect, prevent,
recoverrecover security servicesecurity service
termsterms threat threat –– a a potential for violation of securitypotential for violation of security attack attack –– an an assault on system security, a assault on system security, a
deliberate attempt to evade security servicesdeliberate attempt to evade security services
Passive Attacks (1)Passive Attacks (1)Release of Message ContentsRelease of Message Contents
Passive Attacks (2)Passive Attacks (2)Traffic AnalysisTraffic Analysis
Passive attacks do not affect system resources Eavesdropping, monitoring
Two types of passive attacks Release of message contents Traffic analysis
Passive attacks are very difficult to detect Message transmission apparently normal
• No alteration of the data Emphasis on prevention rather than detection
• By means of encryption
Active Attacks (1)Active Attacks (1)MasqueradeMasquerade
Active Attacks (2)Active Attacks (2)ReplayReplay
Active Attacks (3)Active Attacks (3)Modification of MessagesModification of Messages
Active Attacks (4)Active Attacks (4)Denial of ServiceDenial of Service
Active attacks try to alter system resources or affect their operation
Modification of data, or creation of false data Four categories
Masquerade Replay Modification of messages Denial of service: preventing normal use
• A specific target or entire network Difficult to prevent
The goal is to detect and recover
Security ServiceSecurity Service
enhance security of data processing systems enhance security of data processing systems and information transfers of an organizationand information transfers of an organization
intended to counter security attacksintended to counter security attacks using one or more security mechanisms using one or more security mechanisms often replicates functions normally associated often replicates functions normally associated
with physical documentswith physical documents• which, for example, have signatures, dates; need which, for example, have signatures, dates; need
protection from disclosure, tampering, or protection from disclosure, tampering, or destruction; be notarized or witnessed; be destruction; be notarized or witnessed; be recorded or licensedrecorded or licensed
Security ServicesSecurity Services
X.800:X.800:““a service provided by a protocol layer of a service provided by a protocol layer of
communicating open systems, which ensures communicating open systems, which ensures adequate security of the systems or of data adequate security of the systems or of data transfers”transfers”
RFC 2828:RFC 2828:““a processing or communication service a processing or communication service
provided by a system to give a specific kind of provided by a system to give a specific kind of protection to system resources”protection to system resources”
Security Services (X.800)Security Services (X.800) AuthenticationAuthentication - - assurance that communicating assurance that communicating
entity is the one claimedentity is the one claimed have both peer-entity & data origin authenticationhave both peer-entity & data origin authentication
Access ControlAccess Control - - prevention of the prevention of the unauthorized use of a resourceunauthorized use of a resource
Data ConfidentialityData Confidentiality – –protection of data from protection of data from unauthorized disclosureunauthorized disclosure
Data IntegrityData Integrity - - assurance that data received is assurance that data received is as sent by an authorized entityas sent by an authorized entity
Non-RepudiationNon-Repudiation - - protection against denial by protection against denial by one of the parties in a communicationone of the parties in a communication
AvailabilityAvailability – resource accessible/usable – resource accessible/usable
Security MechanismSecurity Mechanism
feature designed to detect, prevent, or feature designed to detect, prevent, or recover from a security attackrecover from a security attack
no single mechanism that will support all no single mechanism that will support all services requiredservices required
however however one particular element underlies one particular element underlies many of the security mechanisms in use:many of the security mechanisms in use: cryptographic techniquescryptographic techniques
hence our focus on this topichence our focus on this topic
Security Mechanisms (X.800)Security Mechanisms (X.800)
specific security mechanisms:specific security mechanisms: encipherment, digital signatures, access encipherment, digital signatures, access
controls, data integrity, authentication controls, data integrity, authentication exchange, traffic padding, routing control, exchange, traffic padding, routing control, notarizationnotarization
pervasive security mechanisms:pervasive security mechanisms: trusted functionality, security labels, event trusted functionality, security labels, event
detection, security audit trails, security detection, security audit trails, security recoveryrecovery
Model for Network SecurityModel for Network Security
Model for Network SecurityModel for Network Security
using this model requires us to: using this model requires us to: 1.1. design a suitable design a suitable algorithmalgorithm for the security for the security
transformation transformation 2.2. generate the generate the secret information (keys)secret information (keys) used used
by the algorithm by the algorithm 3.3. develop methods to distribute and share the develop methods to distribute and share the
secret information secret information 4.4. specify a specify a protocolprotocol enabling the principals to enabling the principals to
use the transformation and secret use the transformation and secret information for a security service information for a security service
Model for Network Access Model for Network Access SecuritySecurity
Model for Network Access Model for Network Access SecuritySecurity
using this model requires us to: using this model requires us to: 1.1. select appropriate select appropriate gatekeeper functionsgatekeeper functions to to
identify users identify users 2.2. implement implement security controlssecurity controls to ensure only to ensure only
authorised users access designated authorised users access designated information or resources information or resources
Standards
NIST: National Institute of Standards and Technology FIPS: Federal Information Processing
Standards SP: Special Publications
ISOC: Internet Society Home for IETF (Internet Engineering Task
Force) and IAB (Internet Architecture Board) RFCs: Requests for Comments
SummarySummary
topic roadmap & standards organizationstopic roadmap & standards organizations security concepts:security concepts:
confidentiality, integrity, availabilityconfidentiality, integrity, availability X.800 security architectureX.800 security architecture security attacks, services, mechanismssecurity attacks, services, mechanisms models for network (access) securitymodels for network (access) security