Securing Ajax Applications

Risk Analysis

What if something goes wrong? We need a plan. We need to know what to do if we are attacked. We need to know how we can be attacked and the likelihood of an attack. A good process for answering these questions is to develop a threat model for the application.

How do we evaluate the security of an application? Well, first we have to identify what a web application is.

Web Application Anatomy

Web applications potentially connect users anywhere on the planet to your database. On one end these applications face the Internet and process incoming HTTP requests and responses. On the other end they connect to all of the goodies: files, system resources, and data. Because these applications provide access to backend resources they need to be looked at more critically.

Entry points

Entry points are locations in the application that data can enter the system. Data entering the system needs validation. If the data is not validated or inspected before use, it should be considered tainted.

Applications rely on valid data to execute correctly. If tainted data enters the system the application could inadvertently display that data to the user. Likewise, the system could halt or throw an exception thereby revealing information about the application. Attackers look for these types of conditions and exploit them.

Data can enter the application from all sorts of places:

• User input

• Files

• Sockets

• System properties

• Named pipes

• Programmatic interface

• Registry

• Email

• Command-line arguments

• Initialization ...