Analyzing Network Traffic For Incidents

Analyzing Network Traffic For Incidents

Overview

Cybersecurity skill for analyzing network traffic for incidents. Follows industry best practices and security standards.

When to Use

Trigger phrases:

• "analyzing network traffic for incidents"

• "Analyzes network traffic captures and flow data to identify adversary activity d"

• SIEM alerts on anomalous network traffic patterns requiring deeper investigation

• C2 beaconing is suspected and needs confirmation through packet-level analysis

• Data exfiltration volume or destination must be quantified from network evidence

• Lateral movement between systems needs to be traced through network connections

• An IDS/IPS alert requires packet-level validation to confirm or dismiss

Do not use for host-based forensic analysis (process execution, file system artifacts); use endpoint forensics tools instead.

When NOT to Use

• When you lack proper authorization for testing
• For production systems without change management
• When the task requires legal or compliance expertise beyond technical scope

Prerequisites

• Full packet capture (PCAP) infrastructure or on-demand capture capability (network tap, SPAN port)
• Wireshark installed on the analysis workstation with appropriate display filters knowledge
• Zeek (formerly Bro) deployed for network metadata generation (conn.log, dns.log, http.log, ssl.log)
• NetFlow/IPFIX collection from network devices for traffic flow analysis
• Network architecture diagram showing VLAN layout, firewall placement, and monitoring points
• Threat intelligence feeds for correlating observed network indicators

Workflow

# Example: IOC detection
import re

IOC_PATTERNS = {
    "ip": r"\b(?:\d{1,3}\.){3}\d{1,3}\b",
    "domain": r"\b[a-z0-9-]+\.[a-z]{2,}\b",
    "hash_md5": r"\b[a-f0-9]{32}\b",
    "hash_sha256": r"\b[a-f0-9]{64}\b",
}

def extract_iocs(text: str) -> dict:
    return {k: re.findall(v, text) for k, v in IOC_PATTERNS.items()}

1. Scope the Analysis — Define what network traffic artifacts or data sources to examine and the investigation timeline.
2. Preserve Evidence — Create forensic copies of relevant data. Maintain chain of custody documentation.
3. Extract Key Indicators — Use incidents to parse and extract relevant network traffic data points from collected artifacts.
4. Correlate Findings — Cross-reference extracted data with other sources (threat intel, logs, timelines).
5. Build Timeline — Construct a chronological sequence of events related to network traffic.
6. Document Analysis — Write findings report with evidence, conclusions, and recommendations.

Tools

• incidents — Primary tool for this skill
• Forensic Toolkit — Evidence collection and analysis
• Timeline Tools — Chronological event reconstruction
• Log Analysis Platform — Centralized log parsing and search

Process

1. Reconnaissance — Gather target information, identify attack surface, enumerate services
2. Analysis/Exploitation — Execute the technique, analyze results, document findings
3. Reporting — Document IOCs, write findings, provide remediation recommendations

Verification

• All network traffic procedures executed completely and documented
• Findings validated against multiple data sources
• False positives identified and filtered
• Results documented with evidence and timestamps
• Recommendations provided with risk-based prioritization

Anti-Rationalization Table