In the late 1980s and early 1990s, the typical intrusion was fairly straightforward. Intruders most often exploited relatively simple weaknesses, such as poor passwords and misconfigured systems, that allowed greater access to the system than was intended. Once on a system, the intruders exploited one or another well-known, but usually unfixed, vulnerability to gain privileged access, enabling them to use the system as they wished.
There was little need to be more sophisticated because these simple techniques were effective. Vendors delivered systems with default settings that made it easy to break into systems. Configuring systems in a secure manner was not straightforward, and many system administrators did not have the time, expertise, or tools to monitor their systems adequately for intruder activity.
Unfortunately, all these activities continue in 1996; however, more sophisticated intrusions are now common. In eight years of operation, the CERT Coordination Center has seen intruders demonstrate increased technical knowledge, develop new ways to exploit system vulnerabilities, and create software tools to automate attacks. At the same time, intruders with little technical knowledge are becoming more effective as the sophisticated intruders share their knowledge and tools.