introduction into computer...
TRANSCRIPT
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T H E U N I V E R S I T Y O F B R I T I S H C O L U M B I A
Introduction into Computer Security
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• security -- “safety, or freedom from worry”
• thesaurus: peace of mind, feeling of safety, stability, certainty, happiness, confidence.
what is “computer security”?
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in Pali
• Aham avero homi
• Abyapajjho homi
• Anigha homi
• Sukhi attanam pariharami
in English
• May I be safe, free from enmity and danger.
• May I be at peace, free from mental suffering.
• May I be safe, free from physical suffering.
• May I take care of myself, and live happily.
Buddhist chant of metta (loving-kindness)
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• security -- “safety, or freedom from worry”
• thesaurus: peace of mind, feeling of safety, stability, certainty, happiness, confidence.
• where does it come from?
• how can it be achieved?
– make computers too heavy to steal
– buy insurance
– create redundancy (disaster recovery services)
what is “computer security”?
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Ass
et V
alue
Vulnerability Value
Threat
Value
Risk = Asset x Vulnerability x Threat
it’s all about risk management
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example (photos on a smartphone)
from www.apple.com/ca/ios/whats-new/
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• avoid
• transfer
• reduce
• accept
what can be done about risk?
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Source: Common Criteria for Information Technology Security Evaluation. 1999
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example: food for thought
analyze and suggest
1. assets at risk and their value
2. threats to these assets
3. threat agents
4. risk management
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• deterrence
• Deter attacks
• prevention
• Prevent attackers from violating security policy
• detection
• Detect attackers’ violation of security policy
• recovery
• Stop attack, assess and repair damage
• Continue to function correctly even if attack succeeds
• investigation
• Find out how the attack was executed: forensics
• Decide what to change in the future to minimize the risk
goals of computer security
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Solovki Monastery, White Sea, Russia
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Castle of Chillon
from www.picture-newsletter.com/chillon/
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Goal:
Means:
Fortification
• provides safety
• involves layering
• expensive
• requires maintenance
• eventually compromised
Prevent people from violating system’s security policy
conventional fortress-based security
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• no absolute safety
• one weakness/error sufficient
• extra layers at extra cost
• important to understand threats
• limited defender’s resources
• adjust to attacks
• resource suppliers
• distinguishing noncombatants from attackers
• containment
Some points about fortresses
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fortress
• against external attackers
• protects only insiders
• defences cannot change
computer security• control of insiders
• has to keep system usable
• has to protect from new types of attacks
limitations of the fortress analogy
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• Confidentiality
• keeping data and resources hidden
• Integrity
• data integrity (integrity)
• origin integrity (authentication)
• Availability
• enabling access to data and resources
CIA
what computer security policies are concerned with?
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ProtectionAuthorization Accountability Availability
Acc
ess
Con
trol
Dat
a Pr
otec
tion
Audit
Non-Repudiation
Serv
ice
Con
tinui
ty
Dis
aste
r R
ecov
ery
Assurance
Req
uire
men
ts A
ssur
ance
Dev
elop
men
t Ass
uran
ce
Ope
ratio
nal A
ssur
ance
Des
ign
Ass
uran
ceAuthenticationCryptography
conventional approach to computer security
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provided by a set of mechanisms (countermeasures) to prevent bad things (threats) from happening
Protection
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protection against breaking rulesRule examples:
– Only registered students should be able to take exam or fill out surveys
– Only the bank account owner can debit an account
– Only hospital’s medical personnel should have access to the patient’s medical records
– Your example…
Authorization
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• No way to check the rules
– e.g. telephone wire or wireless networks
• No trust to enforce the rules
– e.g., mobile devices
Authorization Mechanisms: Data Protection
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You can tell who did what when
• (security) audit -- actions are recorded in audit log
• Non-repudiation -- evidence of actions is generated and stored
Accountability
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• Service continuity -- you can always get to your resources
• Disaster recovery -- you can always get back to your work after the interruption
Availability
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secure precise broad
set of reachable states set of secure states
types of mechanisms
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Set of things the system builder and the operator of the system do to convince you that it is really safe to use.
• the system can enforce the policy you are interested in, and
• the system works as intended
Assurance
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securing systems
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1. analyze risks
• asset values
• threat degrees
• vulnerabilities
2. develop/change policies
3. choose & develop countermeasures
4. assure
5. go back to the beginning
steps of improving security
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in the following scenario, analyze
1. Assets at risk and their value
2. Threats to these assets
3. Threat agents
4. Ways to manage risk
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ProtectionAuthorization Accountability Availability
Acc
ess
Con
trol
Dat
a Pr
otec
tion
Audit
Non-Repudiation
Serv
ice
Con
tinui
ty
Dis
aste
r R
ecov
ery
Assurance
Req
uire
men
ts A
ssur
ance
Dev
elop
men
t Ass
uran
ce
Ope
ratio
nal A
ssur
ance
Des
ign
Ass
uran
ce
AuthenticationCryptography
Key Points
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• secure, precise, and broad mechanisms
• Risk = Asset x Vulnerability x Threat
• steps of improving security
• classes of threats
• disclosure
• deception
• disruption
• usurpation
key points (cont-ed)