Dependability and its threats: A Taxonomy

1
Availability Reliability Safety Confidentiality In
tegrity Maintainability
Attributes
Fault Prevention Fault Tolerance Fault
Removal Fault Forecasting
Dependability
Means
ability to deliver service that can justifiably
be trusted
Faults Errors Failures
Threats
2
Risk definition and expression

• IEC 61508 (1998) Combination of the probability
  of a damage and of its severity
• MIL-STD-882D (Février 2000) An expression of
  the impact and possibility of a mishap in terms
  of potential mishap severity and probability of
  occurrence

Mishap severity
Negligible
Marginal
Critical
Catastrophic
Frequent
High
Probable
Probability of occurrence
Occasional
Serious
Remote
Low
Medium
Improbable
Appliocation domains (transportation, energy
production, telecommunications, banking, etc.)
Probabilities of occurrence and mishap severity
3

• Risk assessment
• Practices vary according to countries
• France globally at least as relevant (GAMAB)
• UK As low as reasonably possible (ALARP)
• Germany Minimum endogenous mortality (MEM)
• Risk management
• Current situation Risk level ? strength of
  verification and validation activities
• Software considerations in airborne systems and
  equipment certification, DO-178-B
• Common Criteria for Information Technology
  Security Evaluation, ISO/IEC Standard 15408

4
Fault Prevention Fault Tolerance Fault
Removal Fault Forecasting

Means for dependability
Verificationand Validation