A configuration change is an adjustment to how software, a device, or a service behaves after installation or by default. It can be as small as turning a feature on or off, or as important as changing authentication, logging, network access, or update settings. In security, configuration changes matter because defaults shape the first behavior users and systems rely on, and insecure defaults can leave protections disabled or expose data without anyone noticing.
Attackers also target configurations. They may alter settings to weaken defenses, hide activity, persist on a system, or redirect traffic. Defenders watch for unauthorized configuration changes, compare systems to secure baselines, and use change control to make sure updates are intentional and reviewed. In practice, a safe configuration change should be documented, tested, and reversible, especially when it affects access, privacy, or alerting.