A packet capture tool such as tcpdump is essential for examining raw network traffic to identify the nature of the data being transmitted to the external IP address. By capturing the incoming and outgoing packets, the analyst can determine if the pattern corresponds to known malicious activities, such as command and control (C&C) communications, and identify any data exfiltration. Using a vulnerability scanner would typically identify vulnerabilities rather than analyze ongoing traffic for indicators of compromise. Reviewing firewall rules is a preventive step that could potentially stop such traffic but would not analyze it directly for evidence of compromise, and EDR tools are generally focused on endpoint monitoring and would not analyze network traffic at the packet level.