CVE-2021-3766 in objection.js
Summary
by MITRE • 09/06/2021
objection.js is vulnerable to Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
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Analysis
by VulDB Data Team • 09/09/2021
The vulnerability identified as CVE-2021-3766 affects the objection.js library, which is commonly used for mocking HTTP requests in testing environments and development workflows. This security flaw represents a prototype pollution vulnerability that allows attackers to manipulate the prototype of JavaScript objects, potentially leading to arbitrary code execution or other malicious behaviors within applications that rely on this library. The issue stems from improper validation of object property names during runtime modifications, creating opportunities for attackers to inject malicious properties into object prototypes.
Prototype pollution occurs when an application fails to properly sanitize user input or object property names before incorporating them into object prototypes. In the context of objection.js, this vulnerability manifests when the library processes configuration parameters or mock data that contains specially crafted property names designed to modify the Object.prototype directly. This flaw is particularly dangerous because JavaScript prototypes are shared across all instances of objects, meaning that pollution of a prototype affects the entire application's object hierarchy. The vulnerability enables attackers to modify core object behaviors, potentially leading to privilege escalation, denial of service, or remote code execution depending on how the polluted prototype is subsequently used.
The operational impact of this vulnerability extends beyond simple testing environments where objection.js is typically deployed. Applications that use this library for API mocking, integration testing, or development workflows could be compromised if the library receives untrusted input or if the testing environment is exposed to malicious actors. Attackers could exploit this vulnerability to inject malicious properties into the global object prototype, potentially affecting application behavior, causing unexpected crashes, or enabling more sophisticated attacks. The vulnerability is classified under CWE-471, which specifically addresses the improper control of object prototype attributes, and aligns with ATT&CK technique T1059.007 for scripting languages and T1566.001 for spearphishing attachments, as exploitation often occurs through manipulated configuration files or testing data.
Mitigation strategies for CVE-2021-3766 involve immediate library version updates to patched releases that properly sanitize object property names and validate prototype modifications. Organizations should implement strict input validation for any data that might be processed by objection.js or similar mocking libraries, ensuring that property names are properly sanitized before being used to modify object prototypes. Additionally, developers should avoid using user-controlled data directly in prototype modification operations and implement defensive programming practices such as using Object.freeze() or Object.preventExtensions() on critical objects. Security monitoring should include detection of unusual prototype modifications within application logs, and organizations should conduct thorough code reviews to identify any other libraries or components that might be susceptible to similar prototype pollution vulnerabilities. The remediation process should also involve updating all development and testing environments to ensure that the patched versions of objection.js are deployed consistently across all systems where the library is utilized.