Can GTP-U be used for DDoS attacks, and how?

Yes, GTP-U (User Plane) traffic can be used for DDoS attacks. Attackers can generate a massive volume of GTP-U packets, either with legitimate-looking headers but excessive data, or malformed data payloads. This floods the user plane tunnels and the corresponding network elements, consuming bandwidth and processing power, thereby impacting service availability for legitimate user traffic.