Citrix confirms ongoing DDoS attack impacting NetScaler ADCs By 06:26 AM Citrix has confirmed today that an ongoing 'DDoS attack pattern' using DTLS as an amplification vector is affecting Citrix Application Delivery Controller (ADC) networking appliances with EDT enabled. Datagram Transport Layer Security (DTLS) is a communications protocol for securing delay-sensitive apps and services that use datagram transport. DTLS is based on the Transport Layer Security (TLS) protocol and it is designed to prevent eavesdropping and tampering, and to protect data privacy. Reports of the attack have startedtrickling in on December 21st, with customers reporting an ongoing DDOS amplify attack over UDP/443 against Citrix (NetScaler) Gateway devices.