Yup, it is simply being hacked. Whether the hackers are hijacking your cameras for botnetting purposes or just resetting the passwords to wake up the owners, who can say.
There are several things you should do to prevent this from happening again.
1) In your router's web interface, check if any ports are being forwarded to the camera. If so, delete the forwarding rules to the camera.
2) Find your router's UPnP (Universal Plug and Play) and turn it OFF. This so-called "feature" enables devices like your camera to automatically forward ports to themselves without your knowledge, and is responsible for a huge amount of camera hacking.
3) If your router has any access control feature capable of preventing internet access for single IP addresses or IP ranges, use it to block internet access for your camera. This is a safety measure in case your camera has been left infected with a program that makes it part of a botnet, that program will be unable to function if the camera can't get online.
4) In all existing cameras and all cameras you get in the future, turn off their UPnP feature. This is a bit redundant if the router has UPnP disabled already, but it will help if you get a new router and forget to turn off UPnP right away.
If doing all this disables your remote access to the camera(s) then you should learn about VPN and set up a VPN server. This is the secure way to remotely access things. VPN Primer for Noobs
There are several things you should do to prevent this from happening again.
1) In your router's web interface, check if any ports are being forwarded to the camera. If so, delete the forwarding rules to the camera.
2) Find your router's UPnP (Universal Plug and Play) and turn it OFF. This so-called "feature" enables devices like your camera to automatically forward ports to themselves without your knowledge, and is responsible for a huge amount of camera hacking.
3) If your router has any access control feature capable of preventing internet access for single IP addresses or IP ranges, use it to block internet access for your camera. This is a safety measure in case your camera has been left infected with a program that makes it part of a botnet, that program will be unable to function if the camera can't get online.
4) In all existing cameras and all cameras you get in the future, turn off their UPnP feature. This is a bit redundant if the router has UPnP disabled already, but it will help if you get a new router and forget to turn off UPnP right away.
If doing all this disables your remote access to the camera(s) then you should learn about VPN and set up a VPN server. This is the secure way to remotely access things. VPN Primer for Noobs