TCP.Split.Handshake type alert

Message meets Alert condition

The following intrusion was observed: TCP.Split.Handshake.

date=2018-10-23 time=18:00:56 devname=FG200D3916815028 devid=FG200D3916815028 logid=0419016384 type=utm subtype=ips eventtype=signature level=alert vd=root severity=medium srcip=23.234.39.77 srccountry="United States" dstip=172.16.10.38 srcintf="wan1" dstintf="port16" policyid=13 sessionid=71453405 action=detected proto=6 service="ca.vsign.in_http" attack="TCP.Split.Handshake" srcport=13633 dstport=8999 direction=outgoing attackid=26339 profile="all_default" ref="http://www.fortinet.com/ids/VID26339" incidentserialno=257015217 msg="a-ipdf: TCP.Split.Handshake, TCP split handshake at state: ESTABLISHED" crscore=10 crlevel=medium