The correct answer is B because the packet capture shows ICMP echo request traffic carrying data in the packet payload. ICMP echo requests are normally used for ping-style connectivity checks, not for transferring business data. The presence of millions of ICMP packets with payload data, combined with the fact that proprietary information is already appearing on the dark web, strongly indicates data exfiltration over an alternative protocol, often described as ICMP tunneling or protocol misuse.

The official CompTIA CySA+ CS0-003 objectives place this directly under Security Operations, specifically analyzing indicators of potentially malicious activity and using packet capture tools. The objectives explicitly include data exfiltration, unexpected outbound communication, packet capture, Wireshark, and tcpdump as relevant skills and tools for determining malicious activity.

Supporting extract from the CySA+ Study Guide: ICMP echo requests are produced by ping, and “Ping communications take place using the Internet Control Message Protocol (ICMP).” This confirms that the observed Type 8 echo request traffic is ICMP ping-style traffic, not a normal file-transfer or application protocol.

Supporting extract from the Secbay CySA+ guide: “Data Exfiltration: Unauthorized transfer of sensitive data from a system, potentially indicating a data breach or insider threat activity.” The same section also states that “Unexpected Outbound Communication” can indicate communication with malicious or unauthorized entities.

Why the other options are incorrect:

A is not the best answer because the evidence does not prove an insider or a command-and-control channel. The packet capture shows ICMP echo requests with data payloads, which points more directly to exfiltration.

C is incorrect because there is no evidence of malware propagation, scans, sweeps, or attempts to infect other systems.

D is incorrect because an ICMP DDoS would normally involve traffic intended to overwhelm a target. Here, the key indicator is data being carried inside ICMP echo request packets, and the business context is stolen proprietary information on the dark web.

Therefore, the most likely malicious activity is exfiltration over an alternative protocol.