Operational security (OPSEC) is the discipline of protecting critical information about your organization's plans, capabilities, and personnel from adversary collection. In cybersecurity, OPSEC means controlling what attackers can learn about your infrastructure, employees, and security posture.
Infostealer infections are one of the most common OPSEC failures. An employee who installs unapproved software on a work device leaks passwords, internal URLs, and session tokens that reveal organizational structure and access patterns to criminals.