Which of the following network attacks relies on sending an abnormally large packet size that exceeds TCP/ IP specifications?

The ping of death crafts malformed ICMP packets whose total size exceeds the 65,535-byte maximum defined in the IPv4 specification. When the target system reassembles the fragmented oversized packet, it overflows allocated buffers, leading to crashes, freezes, or reboots. This attack directly exploits the TCP/IP specification limit, which matches the question's description of 'abnormally large packet size that exceeds TCP/IP specifications.'

SYN flooding attacks exhaust server connection resources by sending large numbers of TCP SYN packets without completing the three-way handshake, not by sending oversized packets.

TCP hijacking involves an attacker seizing control of an established TCP session by predicting or sniffing sequence numbers, unrelated to packet size.

A Smurf attack amplifies ICMP traffic by broadcasting spoofed ping requests to an entire subnet so all hosts reply to the victim, not by exceeding packet size limits.