Name AJAX Fingerprinting
Summary This attack utilizes the frequent client-server roundtrips in Ajax conversation to scan a system. While Ajax does not open up new vulnerabilities per se, it does optimize them from an attacker point of view. In many XSS attacks the attacker must get a "hole in one" and successfully exploit the vulnerability on the victim side the first time, once the client is redirected the attacker has many chances to engage in follow on probes, but there is only one first chance. In a widely used web application this is not a major problem because 1 in a 1,000 is good enough in a widely used application. A common first step for an attacker is to footprint the environment to understand what attacks will work. Since footprinting relies on enumeration, the conversational pattern of rapid, multiple requests and responses that are typical in Ajax applications enable an attacker to look for many vulnerabilities, well-known ports, network locations and so on.
Prerequisites The user must allow JavaScript to execute in their browser
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: Perform input validation for all remote 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-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-86 Improper Neutralization of Invalid Characters in Identifiers in Web Pages
CWE-96 Improper Neutralization of Directives in Statically Saved Code ('Static Code Injection')
CWE-113 Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting')
CWE-116 Improper Encoding or Escaping of Output
CWE-184 Incomplete Blacklist
CWE-348 Use of Less Trusted Source
CWE-692
CWE-712
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