Intrusion Detection Response Time Calculator
Calculate the total Intrusion Detection and Response Time (IDRT) by summing the time spent across each phase of the incident response lifecycle: detection, analysis, containment, and remediation.
Results will appear here.
Formulas Used
Core Intrusion Detection Response Time (IDRT):
IDRT = T_detection + T_analysis + T_containment + T_remediation
False Positive Overhead per True-Positive Incident:
FP_overhead = (FPR / (1 − FPR)) × T_fp_investigation
Where FPR is the false positive rate as a decimal. This represents the expected analyst time wasted on false alerts for every real incident handled.
Adjusted IDRT:
Adjusted IDRT = IDRT + FP_overhead
Analyst Efficiency Ratio:
Efficiency (%) = (IDRT / Adjusted IDRT) × 100
Component Definitions:
- MTTD (Mean Time to Detect) = T_detection
- MTTR (Mean Time to Respond) = T_analysis + T_containment + T_remediation
Assumptions & References
- All time inputs are in minutes and represent average values per incident.
- The false positive overhead model assumes analysts investigate all alerts before confirming true positives, consistent with real-world SOC workflows.
- The FP overhead formula is derived from the odds ratio: for every true positive, FPR/(1−FPR) false positives are expected at the same alert volume.
- MTTD and MTTR definitions align with NIST SP 800-61 Rev. 2 (Computer Security Incident Handling Guide).
- Industry benchmarks: IBM Cost of a Data Breach Report 2023 cites an average MTTD of 204 days and MTTR of 73 days for breaches; this calculator focuses on the operational SOC response window (minutes to hours).
- SANS Institute recommends a target IDRT of under 1 hour for critical systems.
- False positive rates in enterprise SOCs typically range from 20%–70% (Ponemon Institute, 2022).
- This calculator does not account for parallel response activities, shift handoffs, or escalation delays.