CVE-2022-37598 in UglifyJS
Summary
by MITRE • 10/20/2022
Prototype pollution vulnerability in function DEFNODE in ast.js in mishoo UglifyJS 3.13.2 via the name variable in ast.js. NOTE: the vendor considers this an invalid report.
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Analysis
by VulDB Data Team • 08/03/2024
The vulnerability CVE-2022-37598 represents a prototype pollution flaw within the mishoo UglifyJS 3.13.2 JavaScript minification tool, specifically affecting the DEFNODE function in the ast.js file. This issue arises from improper handling of the name variable parameter, creating a security risk that could potentially allow attackers to manipulate object prototypes in unexpected ways. The vulnerability demonstrates how seemingly benign code processing functions can introduce critical security implications when input validation is insufficient. Prototype pollution vulnerabilities occur when an application allows untrusted data to modify the prototype of an object, leading to potential execution of malicious code or denial of service conditions. The affected component is part of the core AST (Abstract Syntax Tree) processing functionality that UglifyJS uses to parse and manipulate JavaScript code during the minification process.
The technical implementation flaw stems from the DEFNODE function's inadequate validation of the name variable parameter, which is used to define node types within the abstract syntax tree structure. When untrusted input reaches this function without proper sanitization, attackers can inject malicious property names that pollute the Object.prototype, affecting all objects in the JavaScript environment. This particular vulnerability aligns with CWE-471, which specifically addresses the issue of "Modification of Assumed-Immutable Data" where developers assume certain objects or properties remain unchanged. The flaw operates at the intersection of JavaScript's prototype-based inheritance model and the minification process, where the tool's own code processing becomes a vector for exploitation. The vulnerability's impact is particularly concerning because UglifyJS is widely used in production environments for code optimization, making this a potential attack surface for malicious actors targeting web applications.
The operational impact of this prototype pollution vulnerability extends beyond simple code manipulation, potentially enabling attackers to achieve arbitrary code execution or cause application instability. When exploited, the vulnerability could allow adversaries to inject malicious properties into the global prototype chain, affecting all subsequent object operations within the JavaScript environment. This type of vulnerability can lead to various security consequences including but not limited to denial of service attacks, information disclosure, or privilege escalation within applications that rely on UglifyJS for code processing. The vulnerability's classification as invalid by the vendor suggests potential disagreement over the severity assessment or exploitation feasibility, though the underlying prototype pollution mechanism remains a recognized threat in JavaScript environments. Organizations using UglifyJS 3.13.2 should consider the risk implications of this vulnerability, particularly in applications where JavaScript code processing involves untrusted input streams.
Mitigation strategies for this prototype pollution vulnerability should focus on implementing robust input validation and sanitization mechanisms within the affected DEFNODE function. Developers should ensure that all parameter values passed to prototype-modifying functions are properly validated and sanitized before processing. The recommended approach includes implementing strict validation of property names and ensuring that no user-controllable input can directly influence prototype modifications. Security measures should also involve upgrading to patched versions of UglifyJS when available, as newer releases typically contain fixes for known prototype pollution issues. Additionally, organizations should consider implementing runtime protections such as prototype lockdown mechanisms or using alternative minification tools that have demonstrated better resistance to prototype pollution attacks. The implementation of these mitigations aligns with ATT&CK technique T1059.007 for JavaScript, where adversaries may exploit prototype pollution to execute malicious code. Regular security audits of build processes and dependency management should include verification that minification tools are not introducing prototype pollution vulnerabilities into the application stack.