Describe CVE-2018-18931.
What is CVE-2018-18931?
An issue was discovered in the Tightrope Media Carousel digital signage product 7.0.4.104. Due to insecure default permissions on the C:\TRMS\Services directory, an attacker who has gained access to the system can elevate their privileges from a restricted account to full SYSTEM by replacing the Carousel.Service.exe file with a custom malicious executable. This service is independent of the associated IIS web site, which means that this service can be manipulated by an attacker without losing access to vulnerabilities in the web interface (which would potentially be used in conjunction with this attack, to control the service). Once the attacker has replaced Carousel.Service.exe, the server can be restarted using the command "shutdown -r -t 0" from a web shell, causing the system to reboot and launching the malicious Carousel.Service.exe as SYSTEM on startup. If this malicious Carousel.Service.exe is configured to launch a reverse shell back to the attacker, then upon reboot the attacker will have a fully privileged remote command-line environment to manipulate the system further..