Name Cross-Site Scripting via Encoded URI Schemes
Summary An attack of this type exploits the ability of most browsers to interpret "data", "javascript" or other URI schemes as client-side executable content placeholders. This attack consists of passing a malicious URI in an anchor tag HREF attribute or any other similar attributes in other HTML tags. Such malicious URI contains, for example, a base64 encoded HTML content with an embedded cross-site scripting payload. The attack is executed when the browser interprets the malicious content i.e., for example, when the victim clicks on the malicious link.
Prerequisites Target client software must allow scripting such as JavaScript and allows executable content delivered using a data URI scheme.
Solutions Design: Use browser technologies that do not allow client side scripting. Design: Utilize strict type, character, and encoding enforcement. Implementation: Ensure all content that is delivered to client is sanitized against an acceptable content specification. Implementation: Ensure all content coming from the client is using the same encoding; if not, the server-side application must canonicalize the data before applying any filtering. Implementation: Perform input validation for all remote content, including remote and user-generated content Implementation: Perform output validation for all remote content. Implementation: Disable scripting languages such as JavaScript in browser Implementation: Patching software. There are many attack vectors for XSS on the client side and the server side. Many vulnerabilities are fixed in service packs for browser, web servers, and plug in technologies, staying current on patch release that deal with XSS countermeasures mitigates this.
Related Weaknesses
CWE ID Description
CWE-20 Improper Input Validation
CWE-71 Apple '.DS_Store'
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-84 Improper Neutralization of Encoded URI Schemes in a Web Page
CWE-85 Doubled Character XSS Manipulations
CWE-86 Improper Neutralization of Invalid Characters in Identifiers in Web Pages
CWE-697 Insufficient Comparison
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