Chapter 4. APPLICATION LAYER ATTACKS AND DEFENSE

The application layer—layer seven in the OSI Reference Model—is what the lower layers are built for. The explosive growth of the Internet is made possible by the lower layers, but the applications that ride on top of these layers are the fuel that stokes the fire. There are thousands of Internet-enabled applications designed to make complex tasks easier and solve problems for everyone from consumers to governments to multinational corporations. A pervasive concern for all of these applications is security, and so far, judging from the rate of vulnerability announcements from sources like Bugtraq, the status quo is not working so well.

When it comes to breaking into systems, the application layer ...

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