Anything that’s a misuse or uses a networking protocol in ways it wasn’t intended to be used can be considered a threat.

Common examples #

NTP attack #

An attacker can spoof a source IP and submit a type of ntpdc query called monlist. This generates a lot of output and can effectively DoS the target server (spoofed source IP).

DHCP attack #

Hacker can send malformed packets to try to break, gain access, or shut down the DHCP server.

cite: CompTIA Network+