Security Onion + PCAP Investigation: A Comprehensive Overview

Abstract

Introduction

Security Onion is a powerful, open-source platform designed for network security monitoring (NSM), intrusion detection, log management, and incident response. It integrates multiple tools such as Suricata, Zeek, Wireshark, and the ELK stack (Elasticsearch, Logstash, Kibana) to provide a full-featured solution for security operations centers (SOCs). One of its core capabilities is PCAP (Packet Capture) investigation, which captures and analyzes raw network traffic to detect and respond to cyber threats.

Key Features & Components

1. Integrated Tools:

   • Suricata & Zeek for real-time intrusion detection.

   • Wireshark for detailed packet analysis.

   • ELK Stack for log aggregation, visualization, and search.

   • Wazuh for host-based monitoring.

2. PCAP Investigation:

   • Captures every packet on the network.

   • Enables session reconstruction, payload inspection, and attacker identification.

   • Useful for real-time monitoring and post-incident forensics.

3. Alerting System:

   • Real-time alerts triggered by predefined rules in Suricata.

   • Alerts include metadata: IPs, timestamps, threat category, and severity (informational to critical).

How Security Onion Works

1. Data Collection:

   • Monitors network traffic using Zeek and Suricata, saving data as PCAP files.

2. Analysis:

   • Uses tools like Wireshark, Zeek, and the ELK stack to identify malicious traffic and patterns.

3. Detection & Alerting:

   • Detects malware, DDoS, APTs, and abnormal behaviors.

   • Sends alerts for rapid response.

4. Incident Response:

   • Enables forensic analysis, threat containment, and recovery planning.

Benefits and Impacts

• Enhanced Threat Detection: Identifies advanced threats via packet-level inspection.

• Faster Incident Response: Quickly investigates and mitigates security incidents.

• Cost-Effective: Free, open-source alternative to commercial tools.

• Scalable & Flexible: Suitable for small to large-scale networks.

• Forensic Capability: Full traffic capture enables deep post-incident analysis.

Security Operations & Use Cases

1. Detection & Prevention:

   • Signature-based and behavioral analysis.

2. Incident Investigation:

   • Correlate alerts with PCAP data, extract files, perform deep packet inspection.

3. Security Compliance:

   • Helps meet data security and regulatory requirements.

4. Threat Hunting:

   • Analyze historical data for indicators of compromise (IOCs).

5. Training Tool:

   • Ideal for hands-on cybersecurity training and simulated attack response.

6. Network Optimization:

   • Detects performance issues, misuse of resources, and misconfigurations.

Analysis Tools & Interfaces

• Sguil: View and correlate alerts with PCAP data.

• Wireshark: GUI-based inspection of network packets.

• Zeek Logs: Metadata analysis (e.g., DNS, HTTP, file transfers).

• Kibana Dashboards: Visualize logs and network activity in real-time.

• TheHive Integration: Automates incident handling and threat intelligence enrichment.

Conclusion

Security Onion is a comprehensive, scalable solution that enhances an organization\'s ability to detect, analyze, and respond to network threats through PCAP investigation and integrated monitoring tools. It supports proactive defense, incident response, forensic analysis, and regulatory compliance, making it invaluable for any SOC or cybersecurity team.

Copyright

Copyright © 2025 Rajalakshmi R., Akash K., Keshavan T., Rohit K., Vinoth Kumar M.. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.