CompTIA Security+ (SY0-701)Security Program Management and OversightEasy
A security manager states that the frequency of a specific threat event, such as a server hardware failure, is expected to occur once every 5 years based on historical data. Which risk calculation term describes this value?
- AExposure Factor (EF)
- BAnnualized Rate of Occurrence (ARO)
- CSingle Loss Expectancy (SLE)
- DAnnualized Loss Expectancy (ALE)
Show answer & explanationAnswer & explanation
Correct answer: B. Annualized Rate of Occurrence (ARO)
The Annualized Rate of Occurrence (ARO) represents how many times per year a threat event is expected to occur. Here, occurring once every 5 years equals an ARO of 1/5, or 0.2.
Why the other options are wrong
- A. Exposure Factor is the percentage of asset value lost in an incident.
- C. SLE is the monetary loss from a single occurrence, not frequency.
- D. ALE is SLE multiplied by ARO, a dollar figure, not a frequency alone.
Annualized Rate of Occurrence (ARO)
The estimated number of times a specific threat event is expected to occur within a one-year period.
- ARO is expressed as a decimal or frequency (e.g., 0.2 = once every 5 years)
- Used with SLE to calculate ALE: ALE = SLE x ARO
- Derived from historical data, industry statistics, or expert judgment
Memory trick: ARO = how often, SLE = how much, ALE = both combined