Memcached is an open source utility designed to cache in RAM frequently used web pages. But some Linux instances by default have left TCP or UDP port 11211 open to internet-borne requests. One of Arbor Networks’ customers was hit by a 1.7 Tbps reflection/amplification attack on a U.S.-based service provider. Some DDoS extortionists are threatening to unleash DDoS disruptions on victims unless they pay ransoms of 50 monero – aka XMR – cryptocurrency.”]
Source: https://www.cuinfosecurity.com/memcached-ddos-attacks-95000-servers-vulnerable-to-abuse-a-10705