Boogieman, this is Dahua , not Hikvision!
I suggest upgrading firmware to the latest version, setting strong passwords (mix uppercase and lowercase letters, numbers and special characters) and changing ports. Works on Hikvision, hope it works on Dahua too. This happens on systems running with default passwords and ports, no special backdoor needed. Newer versions of Hikvision firmwares do not allow simple passwords, and that's it.