If you are using ZyXEL device and haven't changed the default password , your device might be compromised

An uptick in botnet activity associated with a variant of Mirai. Targeted are ports 23 and 2323 on internet-connected devices made by ZyXEL Communications that are using default credentials.

In October 2016, Mirai malware spread itself to IoT devices gaining access via default password and usernames. The malware then roped affected devices into a botnet and carried out distributed denial of service (DDoS) attacks


For More:
https://threatpost.com/newly-published-exploit-code-used-to-spread-marai-variant/128998/