Intrusion detection is
|“||the process of monitoring events occurring in a computer system or network and analyzing them for signs of intrusion.||”|
|“||[t]he process of identifying that an intrusion has been attempted, is occurring, or has occurred.||”|
There are two different approaches to analyzing events to detect attacks: signature-based detection and anomaly detection.
- Signature-Based Detection. This approach identifies events or sets of events that match with a predefined pattern of events that describe a known attack. These patterns are called signatures. Signatures may include system states, or accessing system areas that have been explicitly identified as “off-limits.”
- Anomaly Detection. Anomaly detection assumes that all intrusive activities deviate from the norm. These tools typically establish a normal activity profile and then maintain a current activity profile of a system. When the two profiles vary by statistically significant amounts, an intrusion attempt is assumed.
- ↑ NIST Special Publication 800-36, at 21.
- ↑ Report on the NS/EP Implications of Intrusion Detection Technology Research and Development, at 6.
- Overview section: NIST Special Publication 800-36, at 21.