Multiple GameSpy 3D 2.62 compatible gaming servers generate very large UDP responses to small requests, which allows remote attackers to use the servers as an amplifier in DDoS attacks with spoofed UDP query packets, as demonstrated using Battlefield 1942.
https://exchange.xforce.ibmcloud.com/vulnerabilities/11084
http://www.securiteam.com/securitynews/5EP0O0K8UO.html