A risk analyst is conducting a quantitative risk assessment for a database server hosting … — CompTIA Security+

A risk analyst is conducting a quantitative risk assessment for a database server hosting core enterprise operational data. The Asset Value ( $AV$ ) of the server is established at $\$500,000$ . Threat intelligence data indicates that a major ransomware incident targeting this database occurs approximately once every 5 years. Financial modeling determines that the Annual Loss Expectancy ( $ALE$ ) for this threat scenario is $\$25,000$ . Based on these quantitative metrics, what is the Exposure Factor ( $EF$ ) associated with a single ransomware incident?

25%Answer
B
5%
C
20%
D
80%

Answer

The Exposure Factor (EF) associated with a single ransomware incident is 25%.

The Exposure Factor (

EF

) measures the percentage of an asset destroyed or damaged during a single threat occurrence. Given

ALE = \$25,000

and

ARO = 0.20

(once every 5 years), the Single Loss Expectancy (

SLE

) is

\$25,000 / 0.20 = \$125,000

. Dividing

SLE

by the total Asset Value (

AV = \$500,000

) gives

EF = \$125,000 / \$500,000 = 0.25

, or 25%.

Step-by-Step Solution

Calculate the Annual Rate of Occurrence (ARO)

ARO = \frac{1}{\text{5 years}} = 0.20

The event occurs once every 5 years, giving an annual frequency of 0.20.

Calculate the Single Loss Expectancy (SLE) from ALE and ARO

SLE = \frac{ALE}{ARO} = \frac{\$25,000}{0.20} = \$125,000

Since

ALE = SLE \times ARO

, dividing

ALE

ARO

yields the expected monetary loss per single incident.

Calculate the Exposure Factor (EF)

EF = \frac{SLE}{AV} = \frac{\$125,000}{\$500,000} = 0.25 \text{ or } 25\%

The Exposure Factor represents the percentage of asset value lost during a single realization of a risk (

SLE = AV \times EF

Key Concept

Quantitative Risk Assessment Metrics (ALE, SLE, ARO, EF)

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