Defeating Hackers and Malware With Disorder

Entropy -- the measure of disorder or randomness -- isn't always desirable in the world of IT security. Kinda, sorta patching your IT systems sometimes, for example, would be a bad thing. At times, though, entropy can be a powerful tool, as in the case of well-chosen passwords that are difficult to crack. A fast-growing SIEM (security incident event managment) company called Vigilant is using entropy in an innovative way that warrants a closer look: Its anomaly-detection service identifies malicious threats based on entropy.

First, a quick primer: Entropy, often measured in bits, is the technical measurement of the randomness of the next piece of data in a string. If you see a sequence of letters with a clear pattern, such as "ABABABABA," you would logically predict the next letter in the series will be B. Because the answer is fairly certain, the entropy would be 0. If you're flipping a coin, the predicted outcome, heads or tails, is considered to be 1 bit of entropy. If a native English speaker is shown a sequence of standard English text and is asked to predict the next letter, he or she could guess it with great accuracy. English text is considered to have an entropy of 0.6 to 1.5 bits.