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5  It’s About the How

5  It’s About the How

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development lifecycle. Different organizations react differently to the need for security,

however, and no two organizations are the same.

We are not going to tell you much about why you should include security testing in

your testing methodology. There are ample books trying to address that question. We

can’t cover what it means to your organization if you have poor security in your software

or how you perform a risk analysis to determine your exposure to software-induced

business risk. Those are important concepts, but they’re beyond the scope of this book.



How, Not What

We are not going to provide you with a database of test data. For example, we will tell

you how you can test for SQL injection or cross-site scripting, but we won’t provide a

comprehensive set of malicious inputs that you can use. There are plenty of resources

for that sort of thing online and we’ll refer you to a few. Given the rapidly changing

nature of software security, you’re better off getting up-to-the-minute attack data online, anyway. The techniques presented in these recipes, however, will last a long time

and will be helpful in delivering attacks of many kinds.



How, Not Where

This book does not present a methodology for assessing your application looking for

weak spots. Assessing a web application—once or on a continuing basis—is not what

we’re helping you do. Assessors come in and find problems. They do not bring the

deep, internal knowledge of the application that the QA staff and developers have.

External consultants do not fit into the software development lifecycle and apply tests

at the unit, integration, and system level. If you need an overall methodology on how

to assess a web application from the ground up, there are many good books on how to

do that. When it’s time to do some of the tasks mentioned in those books, though,

you’ll discover that many are laid out in good detail within the recipes in this book.



How, Not Who

Every organization will have to decide who will perform security testing. It might be

(and probably should be) a combination of both developers and testers. It can involve

folks from the IT security side of the house, too, but don’t let them own security testing

completely. They don’t understand software and software development. If security

testing falls exclusively to the testing and quality side of the organization, then you will

want someone with some software development skills. Although we are not developing

a software product here, the scripts and test cases will be easier to use and reuse if you

have experience with programming and scripting. Even operations staff might benefit

from the recipes in this book.

How you decide whom to assign to these tasks, how you organize their work, and how

you manage the security testing is beyond the scope of this book.



1.5 It’s About the How | 15



How, Not When

Integrating security testing, like any other kind of specialized testing (performance,

fault tolerance, etc.), requires some accommodations in your development lifecycle.

There will be additional smoke tests, unit tests, regression tests, and so on. Ideally these

tests are mapped back to security requirements, which is yet one more place your lifecycle needs to change a little. We are going to give you the building blocks to make

good security tests, but we won’t answer questions about what part of your test cycle

or development methodology to put those tests into. It is difficult to develop security

test cases when security requirements are not specified, but that is a topic for another

book. Instead, we are going to help you build the infrastructure for the test cases. You

will have to determine (by experimenting or by changing your methodology) where

you want to insert them into your lifecycle.



Software Security, Not IT Security

If you play word association games with IT people and say “security,” they’ll often

respond with “firewall.” While firewalls and other network perimeter protections play

an important role in overall security, they are not the subject of this book. We are talking

about software—source code, business logic—written by you, operated by you, or at

least tested by you. We don’t really consider the role of firewalls, routers, or IT security

software like antivirus, antispam, email security products, and so on.

The tests you build using the recipes in this book will help you find flaws in the source

code itself—flaws in how it executes its business functions. This is handy when you

need to check the security of a web application but you do not have the source code

for it (e.g., a third-party application). The techniques are especially powerful when you

have the source itself. Creating narrow, well-defined security tests allows you to facilitate root cause analysis right down to the lines of code that cause the problem.

Although there are products that call themselves “application firewalls” and claim to

defend your application by interposing between your users and youro application, we

will ignore such products and such claims. Our assumption is that the business logic

must be right and that it is our job—as developers, quality assurance personnel, and

software testers—to systematically assess and report on that correctness.



16 | Chapter 1: Introduction



CHAPTER 2



Installing Some Free Tools



Every contrivance of man, every tool, every instrument,

every utensil, every article designed for use, of each and

every kind, evolved from a very simple beginning.

—Robert Collier



These tools can cover the breadth and depth needed to perform comprehensive web

application security testing. Many of these tools will be useful to you, yet some not.

The usefulness of any individual tool will depend heavily on your context—particularly

the web application’s language and what you most need to protect.

This chapter is a reference chapter, even more so than the rest of the book. These recipes

recommend tools and discuss a bit of their use and background. Unlike later chapters,

these recipes don’t directly build up to comprehensive security tests.

Instead, this chapter can be thought of as part of setting up your environment. Just as

you might set up a separate environment for performance testing, you’ll want to set up

at least one workstation with the tools you’ll need for security testing. That said, many

people use the regular QA server and environment for security tests—and this generally

works well. Just beware that any security test failures may corrupt data or take down

the server, impacting existing test efforts.



2.1 Installing Firefox

Problem

The Firefox web browser, with its extensible add-on architecture, serves as the best

browser for web application security testing.



Solution

Using your system default web browser, visit http://www.mozilla.com/en-US/firefox/.

17



Figure 2-1. Approving the View Source Chart extension



Based on your User-Agent string (see Recipe 5.7 for details on User-Agents), the Firefox

website will identify your operating system. Click the Download button, and install

Firefox the same way you would any application. Make sure you have sufficient machine privileges!



Discussion

Even if your application isn’t specifically written for Firefox compatibility, you can use

Firefox to test the less aesthetic, behind the scenes, security-focused aspects. In the case

where using Firefox breaks functionality outright, you will need to rely on web proxies,

command-line utilities, and other browser-agnostic tools.



2.2 Installing Firefox Extensions

Problem

Firefox extensions provide a great deal of additional functionality. We recommend a

few particular extensions for web application security testing. All of these extensions

are installed in a similar fashion.



Solution

Using Firefox, browse to the extension page (listed below).

Click the Install Extension button to add this extension to Firefox, and approve the

installation of the extension when prompted, as shown in Figure 2-1.



18 | Chapter 2: Installing Some Free Tools



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