Organizations determine the required vulnerability scanning for system components and ensure that potential sources of vulnerabilities (e.g., networked printers, scanners, and copiers) are not overlooked. Vulnerability analyses for custom software may require additional approaches, such as static analysis, dynamic analysis, or binary analysis. Organizations can use these approaches in source code reviews and tools (e.g., static analysis tools, web-based application scanners, binary analyzers). Vulnerability scanning includes scanning for patch levels; scanning for functions, ports, protocols, and services that should not be accessible to users or devices; and scanning for improperly configured or incorrectly operating flow control mechanisms. To facilitate interoperability, organizations consider using scanning tools that express vulnerabilities in the Common Vulnerabilities and Exposures (CVE) naming convention. Sources for vulnerability information also include the Common Weakness Enumeration (CWE) listing, the National Vulnerability Database (NVD), and the Common Vulnerability Scoring System (CVSS).