Security companies such as Symantec issue threat alerts on a daily basis. These alerts serve to make IT professionals aware of current malware and attack activity on the Internet. Symantec defines four threat levels, as follows: Low—no discernible network incident activity and no malicious code activity with a moderate or severe risk rating; Medium—increased alertness; a condition that applies when knowledge or the expectation of attack activity is present without specific events occurring or when malicious code reaches a moderate risk rating; High—known threat, a condition that applies when an isolated threat to the computing infrastructure is currently under way or when malicious code reaches a severe risk rating; Extreme—full alert, a condition that applies when extreme global network incident activity is in progress.
Symantec Corporation. Threat Level. [Online, April 12, 2006.] http:// www.sarc.com/.