Outgoing connection to an IRC channel from GeoNetwork

I’m using a GeoNetwork 3.10 service installed on an Ubuntu 18 server, and noticed that this server often experiences what seems to be Denial-Of-Service attacks, overwhelming Apache and Tomcat.
I then ran the following command to check the outgoing connections made by the server :

netstat -putw

I noticed that GeoNetwork apparently connects an external IRC channel :

tcp6       0      0 geocatalogue.afric:http irc.efnet.nl:ircd       SYN_RECV    -

Is there any explanation for this ? It seems that it is a backdoor being exploited. Is there any possibility to block this suspicious script and to identify the part of the GeoNetwork code doing this ?

EDIT : I’m not 100% sure that the outgoing connection is performed by GeoNetwork (netstat doesn’t list nor java nor the pid of the involved process) but the problem appeared after having upgraded GeoNetwork from 3.0 to 3.10….