A number of sources, including DShield, have noticed an uptick on port 2323 TCP beginning around 3 weeks ago.

This is the scanner portion of the Mirai botnet scanning for IoT devices on both 23/TCP and 2323/TCP.   There are a number of IoT devices that use port 2323/TCP as an alternate port for Telnet.  Those who have setup listeners on port 2323 are seeing brute force credential attacks utilizing a small dictionary.

The Mirai botnet iwas used to attempt to DDOS Brian Krebs website i and ifor the nearly 1 Tbps DDOS against OVH in late September

-- Rick Wanner MSISE - rwanner at isc dot sans dot edu - http://namedeplume.blogspot.com/ - Twitter:namedeplume (Protected)