The ethical hacker is likely performing an SYN scan to stealthily identify open ports without fully establishing a connection. An SYN scan, also known as a half-open scan or a stealth scan, is a type of port scanning technique that exploits the TCP three-way handshake process. The hacker sends an SYN packet to a target port and waits for a response. If the target responds with an SYN/ACK packet, it means the port is open and listening for connections. If the target responds with an RST packet, it means the port is closed and not accepting connections. However, instead of completing the handshake with an ACK packet, the hacker sends an RST packet to abort the connection. This way, the hacker avoids creating a full connection and logging an entry in the target’s system, making the scan less detectable and intrusive. The hacker can repeat this process for different ports and identify which ones are open and potentially vulnerable to exploitation12.

The other options are not correct for the following reasons:

B. They are performing a TCP connect scan to identify open ports on the target machine: This option is incorrect because a TCP connect scan involves establishing a full connection with the target port by completing the TCP three-way handshake. The hacker sends an SYN packet, receives an SYN/ACK packet, and then sends an ACK packet to finalize the connection. Then, the hacker terminates the connection with an RST or FIN packet. A TCP connect scan is more reliable and compatible than an SYN scan, but also more noisy and slow, as it creates more traffic and logs on the target system12.

C. They are performing a vulnerability scan to identify any weaknesses in the target system: This option is incorrect because a vulnerability scan is a broader and deeper process than a port scan. A vulnerability scan involves identifying and assessing the security flaws and risks in a system or network, such as missing patches, misconfigurations, outdated software, or weak passwords. A vulnerability scan may use port scanning as one of its techniques, but it also uses other methods, such as banner grabbing, service enumeration, or exploit testing. A vulnerability scan usually requires more time, resources, and permissions than a port scan34.

D. They are performing a network scan to identify live hosts and their IP addresses: This option is incorrect because a network scan is a different process than a port scan. A network scan involves discovering and mapping the devices and hosts connected to a network, such as routers, switches, servers, or workstations. A network scan may use ping, traceroute, or ARP requests to identify the IP addresses, MAC addresses, and hostnames of the live hosts. A network scan usually precedes a port scan, as it provides the target range and scope for the port scan56.

References:

1: Port Scanning Techniques - an overview | ScienceDirect Topics

2: nmap Host Discovery Techniques

3: Vulnerability Scanning Tools | OWASP Foundation

4: What Is Vulnerability Scanning? Types, Tools and Best Practices | Splunk

5: Network Scanning - an overview | ScienceDirect Topics

6: Network Scanning - Nmap