The document provides information on several digital signage systems and related security issues, including:
1) Eight cases of vulnerabilities found in different digital signage systems are described, such as remote code execution, SQL injection, authentication bypass, and more.
2) Common attack vectors for digital signage systems are explained, including exposed management interfaces, known vulnerabilities, default or hard-coded credentials, lack of authentication and authorization, and more.
3) Details are given on specific exploits against systems like Cayin, QiHang Media, UBICOD Medivision, and others, demonstrating privilege escalation, unauthorized file access and deletion, and in some cases gaining full remote code execution.