It's most likely due to read through thread
Hikvision camera resets ITSELF to factory default twice! and
Full Disclosure: Access control bypass in Hikvision IP Cameras
It happened to two of my cameras that were port forwarded around September 23rd. I knew there were risks to making cameras remotely accessible through port forwarding, but hadn't had any issue after years of doing it until the backdoor vulnerability came out. Since mine are Chinese PTZ cameras (Imporx brand) that have Hikvision modules rather than Hikvsion from head to toe, I don't think I will have an easy time obtaining firmware that addresses the vulnerability. I've now gone to using
Blue Iris Blue Iris - Video Security Software for the cameras which can be setup for remote viewing through an Android app
Blue Iris - Android Apps on Google Play
Changing your IP address will most likely do nothing, there is most likely a botnet, someone running scripts that scans millions of IP addresses and looks for the vulnerability and resets them in mass. Both my cameras were in completely different locations, hours away from each other on unrelated Internet service providers. Both of them got factory reset within days of each other. I brought one back up, and it reset itself within about day and a half. After I searched forums and found out about the exploit, turned off port forwarding and it hasn't happened since. The cameras had been running fine since 2014 and to my knowledge had never been hacked previously. I do miss being able to access them directly remotely, but Blue Iris does a pretty good job and is highly configurable. Blue Iris can be setup for HTTPS via stunnel.
It's obviously possible that someone discovers and discloses a vulnerability in Blue Iris, although since they update frequently, it should be addressed promptly. As others suggested, the most prudent method is to only access through VPN, although that makes things a bit more complicated when you just simply want to open up an app on your phone to quickly view remotely.
