alert udp any any -> any 123 (
msg:"ET DOS Possible NTP DDoS Inbound Frequent Un-Authed PEER_LIST Requests IMPL 0x03";
content:"|00 03 00|"; offset:1; depth:3;
byte_test:1,!&,128,0;
byte_test:1,&,4,0;
byte_test:1,&,2,0;
byte_test:1,&,1,0;
threshold:type both,track by_dst,count 2,seconds 60;
reference:url,community.rapid7.com/community/metasploit/blog/2014/08/25/r7-2014-12-more-amplification-vulnerabilities-in-ntp-allow-even-more-drdos-attacks;
classtype:attempted-dos;
sid:2019016; rev:3;
metadata:created_at 2014_08_26, confidence Medium, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2019_07_26;
)