Unsafe jQuery plugin¶
ID: js/unsafe-jquery-pluginKind: path-problemSecurity severity: 6.1Severity: warningPrecision: highTags: - security - external/cwe/cwe-079 - external/cwe/cwe-116 - frameworks/jqueryQuery suites: - javascript-code-scanning.qls - javascript-security-extended.qls - javascript-security-and-quality.qls
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Library plugins, such as those for the jQuery library, are often configurable through options provided by the clients of the plugin. Clients, however, do not know the implementation details of the plugin, so it is important to document the capabilities of each option. The documentation for the plugin options that the client is responsible for sanitizing is of particular importance. Otherwise, the plugin may write user input (for example, a URL query parameter) to a web page without properly sanitizing it first, which allows for a cross-site scripting vulnerability in the client application through dynamic HTML construction.
Recommendation¶
Document all options that can lead to cross-site scripting attacks, and guard against unsafe inputs where dynamic HTML construction is not intended.
Example¶
The following example shows a jQuery plugin that selects a DOM element, and copies its text content to another DOM element. The selection is performed by using the plugin optionsourceSelector as a CSS selector.
jQuery.fn.copyText=function(options){// BAD may evaluate `options.sourceSelector` as HTMLvarsource=jQuery(options.sourceSelector),text=source.text();jQuery(this).text(text);}
This is, however, not a safe plugin, since the call tojQuery interpretssourceSelector as HTML if it is a string that starts with<.
Instead of documenting that the client is responsible for sanitizingsourceSelector, the plugin can usejQuery.find to always interpretsourceSelector as a CSS selector:
jQuery.fn.copyText=function(options){// GOOD may not evaluate `options.sourceSelector` as HTMLvarsource=jQuery.find(options.sourceSelector),text=source.text();jQuery(this).text(text);}
References¶
OWASPDOM Based XSS.
Wikipedia:Cross-site scripting.
jQuery:Plugin creation.
Bootstrap:XSS vulnerable bootstrap plugins.
Common Weakness Enumeration:CWE-79.
Common Weakness Enumeration:CWE-116.