An analyst discovers that a legitimate security alert has been dismissed.

A false negative occurs when an intrusion detection system (IDS) fails to detect and report actual malicious activity. This means that a legitimate security alert has been dismissed or overlooked, allowing potentially harmful traffic to pass through the network undetected. The impact of false negatives can be significant as they represent missed opportunities to stop or mitigate security threats1.

References := Cisco documentation on security systems, such as IPS (Intrusion Prevention System), discusses the importance of accurately detecting malicious activity and the risks associated with false negatives, which include the failure to trigger alerts for actual attacks1.