False Positive
What is False Positive?
False PositiveA security alert that flags benign activity as malicious, costing analyst time and eroding trust in the detection that produced it.
A false positive occurs when a detection rule, signature, or anomaly model classifies legitimate behavior as a threat. Common sources include broad signatures, dynamic test environments, software updates, scheduled scans, and overly aggressive baselines. False positives are expensive because each one consumes analyst attention, can trigger SOAR playbooks, and contributes to alert fatigue. Detection engineering teams measure the false-positive rate per rule, tune logic, add allowlists or context enrichment, and retire rules that cannot be made specific enough. The goal is not zero alerts but a defensible balance between precision, recall, and operational cost.
● Examples
- 01
An IDS rule flags a vulnerability scanner run by the security team itself as an attack.
- 02
An EDR rule treats a software updater that spawns a PowerShell child process as malicious behavior.
● Frequently asked questions
What is False Positive?
A security alert that flags benign activity as malicious, costing analyst time and eroding trust in the detection that produced it. It belongs to the Defense & Operations category of cybersecurity.
What does False Positive mean?
A security alert that flags benign activity as malicious, costing analyst time and eroding trust in the detection that produced it.
How does False Positive work?
A false positive occurs when a detection rule, signature, or anomaly model classifies legitimate behavior as a threat. Common sources include broad signatures, dynamic test environments, software updates, scheduled scans, and overly aggressive baselines. False positives are expensive because each one consumes analyst attention, can trigger SOAR playbooks, and contributes to alert fatigue. Detection engineering teams measure the false-positive rate per rule, tune logic, add allowlists or context enrichment, and retire rules that cannot be made specific enough. The goal is not zero alerts but a defensible balance between precision, recall, and operational cost.
How do you defend against False Positive?
Defences for False Positive typically combine technical controls and operational practices, as detailed in the full definition above.
What are other names for False Positive?
Common alternative names include: FP, Benign alert.
● Related terms
- defense-ops№ 405
False Negative
Malicious activity that a detection failed to flag, leaving the threat unnoticed and allowing the attacker to continue without alerting defenders.
- defense-ops№ 041
Alert Fatigue
The desensitization of analysts caused by excessive, low-value, or repetitive security alerts that erodes attention and slows real incident response.
- defense-ops№ 307
Detection Engineering
The discipline of designing, testing, deploying, and maintaining security detections as code, with measurable coverage of adversary techniques.
- defense-ops№ 1039
SIEM
A platform that aggregates, normalizes and correlates security telemetry from across the enterprise to enable detection, investigation, compliance and reporting.
- network-security№ 048
Anomaly-Based Detection
A detection approach that builds a baseline of normal activity and flags deviations from it as potentially malicious.
● See also
- № 1040SIEM Rule Tuning