During a red team assessment at a retail bank in New York, ethical hacker Aisha...

This is a SYN flood because the attack floods the target with TCP SYN packets (connection initiation). The server responds by allocating resources and sending SYN-ACK replies, moving each connection into a half-open state while it waits for the client’s final ACK to complete the three-way handshake. In a SYN flood, that final ACK never arrives (often because the source addresses are spoofed or because the attacker deliberately does not complete the handshake). As a result, the server’s backlog queue of pending connections fills up, consuming memory/connection slots and preventing legitimate users from establishing new sessions.

The scenario’s language matches the mechanics precisely: “flood of TCP connection initiation packets,” “exhausting the server’s backlog of half-open connections,” and “never receives the final ACK.” Those are the classic identifiers of SYN flooding.

Why the other options are incorrect:

ACK flood (A) involves flooding with TCP ACK packets; it does not primarily create half-open handshakes because ACKs are not the connection-initiation step.

TCP SACK Panic (B) refers to a specific vulnerability/issue related to TCP Selective Acknowledgment processing, not a generic handshake backlog exhaustion attack pattern.

APT attack (C) is not a DoS attack type; it refers to advanced persistent threat campaigns and is unrelated to TCP handshake flooding.

Therefore, Aisha is simulating D. SYN Flood Attack.