This document discusses the limitations of modern network security tools and techniques. It provides examples of how malware authors are able to evade detection from antivirus software, network filters, and other defenses by using techniques like domain generation algorithms, encoding payloads in images and documents, and compromising legitimate websites and infrastructure to host and distribute attacks. The document argues that security vendors struggle to keep up with the constantly evolving tactics of cybercriminals, and that non-targeted social engineering attacks remain an effective way to compromise users.