CVE-2021-3815 in utils.js
Summary
by MITRE • 12/08/2021
utils.js is vulnerable to Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
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Analysis
by VulDB Data Team • 12/11/2021
The vulnerability identified as CVE-2021-3815 resides within the utils.js library and represents a critical prototype pollution flaw that enables attackers to manipulate object prototypes in unintended ways. This issue specifically affects the improper handling of object prototype attributes during runtime operations, allowing malicious actors to inject malicious code or alter application behavior through crafted input data. The vulnerability manifests when applications using this library fail to properly validate or sanitize user-supplied data before incorporating it into object prototype structures, creating opportunities for attackers to modify core JavaScript object behaviors.
Prototype pollution vulnerabilities occur when an application fails to properly validate input data that is used to set properties on object prototypes, potentially allowing attackers to modify the behavior of all objects that inherit from those prototypes. This flaw is categorized under CWE-471 as "Modification of Externally-Controlled Reference Data Structure" and can be mapped to ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript' where attackers leverage such vulnerabilities to execute arbitrary code. The vulnerability is particularly dangerous because it can affect the entire application runtime environment, potentially enabling attackers to escalate privileges, bypass security controls, or manipulate application logic.
The operational impact of this vulnerability extends beyond simple data corruption, as it can lead to complete application compromise when exploited. Attackers can leverage prototype pollution to inject malicious properties into prototype objects, which then propagate to all instances of that object type throughout the application. This can result in unauthorized access, data manipulation, or even remote code execution depending on the application's architecture and how it handles object instantiation. The vulnerability affects applications that use the utils.js library for object manipulation, data processing, or configuration handling, particularly those that dynamically process user input without proper sanitization measures. When exploited, this vulnerability can allow attackers to manipulate core application functionality, potentially leading to complete system compromise.
Mitigation strategies for CVE-2021-3815 should focus on implementing comprehensive input validation and sanitization measures across all application layers that interact with the utils.js library. Organizations should immediately update to patched versions of the library where available, as the vulnerability requires no user interaction for exploitation and can be triggered through any input that reaches the vulnerable code path. Security measures should include implementing prototype validation checks, using secure coding practices that prevent direct assignment to prototype properties, and employing runtime monitoring to detect anomalous object property modifications. Additional protective measures include code reviews focusing on prototype handling patterns, implementing strict input validation for all external data sources, and utilizing security tools that can detect prototype pollution patterns during application runtime. Organizations should also consider implementing application sandboxing or containerization to limit the potential impact of successful exploitation attempts. The vulnerability highlights the importance of following secure coding practices and adhering to industry standards such as OWASP Top Ten and NIST cybersecurity frameworks to prevent similar issues in future development cycles.