Understanding and Handling False Positives

False positives occur when legitimate IPs are incorrectly identified as malicious. Understanding why they happen helps minimize their impact.

What is a False Positive?

A false positive in the context of IP blocklists is when a legitimate IP address is incorrectly flagged as malicious and blocked from accessing services.

False positives can disrupt business operations, frustrate users, and damage customer relationships if not handled properly.

Common Causes

• Shared IP Addresses - NAT, proxies, and VPNs mean multiple users share IPs - one bad actor can affect many innocent users
• IP Reassignment - Dynamic IPs are reassigned; a previously malicious IP may now belong to a legitimate user
• Compromised Systems - Legitimate servers get infected with malware and listed, then cleaned but remain listed
• Overly Aggressive Rules - Blocking entire ranges when only specific IPs are problematic

Minimizing False Positives

Strategies to reduce false positive impact:

• Use Confidence Scores - Block high-confidence threats, challenge medium, allow low
• Implement Decay - Let old listings expire if no new malicious activity is observed
• Allow Disputes - Provide a clear process for legitimate users to report false positives

Remediation Process

If you believe your IP was incorrectly listed:

1. Check the listing details to understand why the IP was flagged
2. Verify the issue has been resolved (malware removed, spam stopped)
3. Submit a dispute request with evidence of remediation
4. Monitor the IP for new issues that could cause re-listing