A comparison of the block performances of multiple protection technologies reveals a significant correlation of failures to detect exploits. The number of exploits that were able to bypass layers of security is significantly higher than is the prediction for risk models ignoring correlation. This not only raises questions about risk models that underestimate or ignore correlation, but also considerably impacts currently held beliefs about the effectiveness of layered security. How does an organization ensure effective breach protection and defend against exploits that are able to escape detection by several layers of defense? This analyst brief provides answers to the challenge.