We don’t yet know the root cause(s) that forced Marriott this week to disclose a four-year-long breach involving the personal and financial information of 500 million guests of its Starwood hotel properties. But anytime we see such a colossal intrusion go undetected for so long, the ultimate cause is usually a failure to adopt the most important principle in cybersecurity defense that applies to both corporations and consumers: Assume you are compromised.
For companies, this principle means accepting the notion that it is no longer possible to keep the bad guys out of your networks entirely. This doesn’t mean abandoning all tenets of traditional defense, such as quickly applying software patches and using technologies to block or at least detect malware infections.