The vulnerability exists due to improper handling of service configuration files. NSSM uses a configuration file to store service settings, and these files are stored in a directory that is writable by the SYSTEM user. When a user with limited privileges attempts to start a service using NSSM, the service manager will attempt to read and write to the configuration file.

An attacker can exploit this vulnerability by creating a malicious configuration file with elevated privileges. When a user with limited privileges attempts to start a service using NSSM, the service manager will execute the malicious configuration file, allowing the attacker to gain elevated privileges.

# Malicious configuration file path malicious_config_file = os.path.join(config_dir, ' malicious_config.txt')