CVE-2020-24939 in Supermixer
Summary
by MITRE • 06/16/2021
Prototype pollution in Stampit supermixer 1.0.3 allows an attacker to modify the prototype of a base object which can vary in severity depending on the implementation.
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Analysis
by VulDB Data Team • 06/19/2021
Prototype pollution vulnerabilities occur when an application fails to properly validate or sanitize user input that is used to modify object prototypes. In the case of CVE-2020-24939 affecting Stampit supermixer version 1.0.3, this vulnerability allows attackers to inject malicious data into the prototype chain of base objects, potentially enabling arbitrary code execution or other security breaches. The flaw exists because the library does not adequately check or sanitize incoming data before using it to extend or modify object prototypes, creating a pathway for attackers to manipulate the fundamental structure of objects within the application's memory space.
The technical implementation of this vulnerability stems from how Stampit processes object merging and inheritance operations. When the supermixer function is called with user-controlled input, it fails to properly isolate or validate the properties being added to objects, allowing attackers to inject properties that modify the Object.prototype directly. This creates a dangerous situation where any object in the application's prototype chain can be polluted, potentially affecting all subsequent object instantiations that inherit from the modified prototype. The severity of this vulnerability varies significantly based on how the application implements object creation and property access patterns, with some implementations being more susceptible to exploitation than others.
The operational impact of CVE-2020-24939 extends beyond simple data manipulation, as it can lead to serious security consequences including privilege escalation, denial of service, and in some cases, complete system compromise. When an attacker successfully pollutes a prototype, they can potentially manipulate core application functionality, inject malicious properties that persist across different object instances, or even override critical methods that control application behavior. The vulnerability is particularly dangerous because it can be exploited through various attack vectors including API endpoints, configuration files, or user input fields that are processed by the Stampit library. The indirect nature of the attack means that even if the direct interface to the vulnerable library is not exposed to user input, indirect access through other components that utilize Stampit can still lead to successful exploitation.
This vulnerability maps directly to CWE-471, which specifically addresses the weakness of "Modification of Assumed-Immutable Data" and aligns with ATT&CK technique T1059.001 for command and script injection. Organizations should implement immediate mitigations including updating to patched versions of Stampit supermixer, implementing input validation and sanitization at all levels where object merging occurs, and conducting thorough code reviews to identify other potential prototype pollution vectors within their applications. Additionally, developers should employ defensive programming practices such as using Object.freeze() on critical objects, implementing proper property enumeration controls, and ensuring that all user-supplied data is validated before being used in object construction or modification operations. The remediation process should also include monitoring for any suspicious prototype modifications in production environments and implementing runtime protections that can detect and block prototype pollution attempts.