OWASP Software Assurance Maturity Model

Operations
The Operations Business Function encompasses those activities necessary to ensure confidentiality, integrity, and availability are maintained throughout the operational lifetime of an application and its associated data. Increased maturity with regard to this Business Function provides greater assurance that the organization is resilient in the face of operational disruptions, and responsive to changes in the operational landscape.

Environment Management
The organization’s work on application security doesn’t end once the application becomes operational. New security features and patches are regularly released for the various elements of the technology stack you’re using, until they become obsolete or are no longer supported.
Most of the technologies in any application stack are not secure by default. This is frequently intentional, to enhance backwards compatibility or ease of setup. For this reason, ensuring the secure operation of the organization’s technology stack requires the consistent application of secure baseline configurations to all components. The Environment Management (EM) practice focuses on keeping your environment clean and secure.
Vulnerabilities are discovered throughout the lifecycles of the technologies on which your organization relies, and new versions addressing them are released on various schedules. This makes it essential to monitor vulnerability reports and perform orderly, timely patching across all affected systems.