2KKUU7ita

Figure 14-7:
Script code
reflected to
the browser.
Chapter 14: Websites and Applications
If your budget is limited, you may consider using a free SQL injection tool such
as SQL Power Injector (www.sqlpowerinjector.com) or the Firefox Addon,
SQL Inject Me (https://addons.mozilla.org/en-us/firefox/
addon/sql-inject-me).
I cover database security in depth in Chapter 15.
Cross-site scripting
Cross-site scripting (XSS) is perhaps the most well-known web vulnerability
that occurs when a web page displays user input — typically via JavaScript—
that isn’t properly validated. A criminal hacker can take advantage of the
absence of input filtering and cause a web page to execute malicious code on
any user’s computer that views the page.
For example, an XSS attack can display the user ID and password login page
from another rogue website. If users unknowingly enter their user IDs and
passwords in the login page, the user IDs and passwords are entered into the
hacker’s web server log file. Other malicious code can be sent to a victim’s
computer and run with the same security privileges as the web browser or
e-mail application that’s viewing it on the system; the malicious code could
provide a hacker with full Read/Write access to browser cookies, browser
history files, or even permit the download/installation of malware.
A simple test shows whether your web application is vulnerable to XSS. Look
for any fields in the application that accept user input (such as on a login or
search form), and enter the following JavaScript statement:
alert(‘XSS’)
If a window pops up that reads XSS, as shown in Figure 14-7, the application
is vulnerable.
There are many more iterations for exploiting XSS, such as those requiring
user interaction via the JavaScript onmouseover function. As with SQL injection,
you really need to use an automated scanner to check for XSS. Both
WebInspect and Acunetix Web Vulnerability Scanner do a great job of finding
XSS. However, they often tend to find different XSS issues, a detail that highlights
the importance of using multiple scanners when you can. Figure 14-8
shows some sample XSS findings in Acunetix Web Vulnerability Scanner.
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