CVE-2020-28503 in copy-props
Summary
by MITRE • 03/23/2021
The package copy-props before 2.0.5 are vulnerable to Prototype Pollution via the main functionality.
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Analysis
by VulDB Data Team • 04/03/2021
The vulnerability identified as CVE-2020-28503 affects the copy-props npm package version prior to 2.0.5, representing a critical prototype pollution flaw that can be exploited by attackers to manipulate object prototypes within JavaScript applications. This type of vulnerability occurs when an application fails to properly validate or sanitize user-provided input that is used to set properties on objects, allowing malicious actors to inject properties into the Object.prototype chain. The affected package serves as a utility for copying properties between objects, making it a common dependency in many Node.js applications and build processes.
The technical mechanism behind this prototype pollution vulnerability involves the package's handling of property names during the copying process. When the copy-props function processes user-controllable input without proper sanitization, it can inadvertently set properties on the Object.prototype object itself rather than on the intended target object. This occurs because JavaScript's prototype chain allows properties set on Object.prototype to be inherited by all objects, creating a persistent security risk that can affect the entire application runtime. The vulnerability is classified under CWE-471, which specifically addresses the issue of using insecure functions that can lead to prototype pollution attacks.
The operational impact of this vulnerability extends beyond simple data manipulation, as prototype pollution can enable attackers to perform various malicious activities including but not limited to remote code execution, denial of service attacks, and privilege escalation within applications. When exploited, this vulnerability can allow attackers to inject malicious properties into the prototype chain, potentially affecting the behavior of other parts of the application that rely on standard object methods or properties. The attack surface is particularly concerning because copy-props is frequently used in build systems, configuration management tools, and various automation scripts where it may process untrusted input from external sources.
Mitigation strategies for CVE-2020-28503 primarily involve upgrading the affected package to version 2.0.5 or later, which includes proper input validation and sanitization measures to prevent prototype pollution. Organizations should conduct comprehensive dependency audits to identify all instances of the vulnerable package across their codebase and ensure that all affected applications are updated promptly. Additionally, implementing proper input validation at multiple layers of the application architecture can provide defense-in-depth against similar vulnerabilities. Security practitioners should also consider implementing runtime protections such as prototype pollution detection mechanisms and monitoring for unusual property additions to prototype objects, aligning with ATT&CK technique T1068 which covers exploit for privilege escalation through prototype pollution. The vulnerability underscores the importance of maintaining up-to-date dependencies and implementing robust security controls in software development lifecycle processes to prevent such critical flaws from being exploited in production environments.