The Web Application Hacker’s Handbook Discovering and Exploiting Security Flaws

that protects users from malicious cloned sites.

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Most banks won’t take responsibility if their customers visit a cloned

web site. They cannot disassociate themselves so easily if customers

are attacked via an XSS flaw in their own application.

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As you will see, there are ways of delivering XSS attacks that do not

use phishing-style techniques.

Stored XSS Vulnerabilities

A different category of XSS vulnerability is often referred to as stored cross-site

scripting. This version arises when data submitted by one user is stored within

the application (typically in a back-end database) and then displayed to other

users without being filtered or sanitized appropriately.

Stored XSS vulnerabilities are common in applications that support interac-

tion between end users, or where administrative staff access user records and

data within the same application. For example, consider an auction applica-

tion that allows buyers to post questions about specific items, and sellers to