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HTML5 storage manipulation (stored DOM-based)

Description: HTML5 storage manipulation (stored DOM-based)

Stored DOM-based vulnerabilities arise when user input is stored and later embedded into a response within a part of the DOM that is then processed in an unsafe way by a client-side script. An attacker can leverage the data storage to control a part of the response (for example, a JavaScript string) that can be used to trigger the DOM-based vulnerability.

HTML5 storage manipulation arises when a script stores controllable data in the HTML5 storage of the web browser (either localStorage or sessionStorage). An attacker may be able to use this behavior to construct a URL that, if visited by another application user, will cause the user's browser to store attacker-controllable data.

This behavior does not in itself constitute a security vulnerability. However, if the application later reads the data back from storage and processes it in an unsafe way, then an attacker may be able to leverage the storage mechanism to deliver other DOM-based attacks, such as cross-site scripting and JavaScript injection.

Burp Suite automatically identifies this issue using dynamic and static code analysis. Static analysis can lead to false positives that are not actually exploitable. If Burp Scanner has not provided any evidence resulting from dynamic analysis, you should review the relevant code and execution paths to determine whether this vulnerability is indeed present, or whether mitigations are in place that would prevent exploitation.

Remediation: HTML5 storage manipulation (stored DOM-based)

The most effective way to avoid DOM-based HTML5 storage manipulation is not to place in HTML5 storage any data that originated from any untrusted source. If the desired functionality of the application means that this behavior is unavoidable, then defenses must be implemented within the client-side code to prevent malicious data from being stored.


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