Citrix has released a feature enhancement designed to block attackers from using the Datagram Transport Layer Security (DTLS) feature of Citrix ADC and Gateway devices as an amplification vector in DDoS attacks. The new DTLS feature enhancement adds a “HelloVerifyRequest”” setting that will address the susceptibility to this attack vector and will block attempts made by attackers to abuse them in future attacks. Customers who use DTLS can also temporarily remove the amplification vector by temporarily disabling the DTLS. The effect of this attack appears to be more prominent on connections with limited bandwidth.”
Source: https://www.bleepingcomputer.com/news/security/citrix-adds-netscaler-adc-setting-to-block-recent-ddos-attacks/