CVE-2018-3722 in merge-deep
Summary
by MITRE
merge-deep node module before 3.0.1 suffers from a Modification of Assumed-Immutable Data (MAID) vulnerability, which allows a malicious user to modify the prototype of "Object" via __proto__, causing the addition or modification of an existing property that will exist on all objects.
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Analysis
by VulDB Data Team • 03/21/2023
The CVE-2018-3722 vulnerability resides within the merge-deep node module version 3.0.1 and earlier, representing a critical modification of assumed-immutable data flaw that fundamentally compromises object integrity within javascript applications. This vulnerability falls under the CWE-1047 category, which specifically addresses issues where developers assume object properties or prototypes remain immutable, creating dangerous attack vectors for malicious actors. The flaw enables attackers to manipulate the Object prototype through the _proto_ property, a mechanism that should remain protected from user-controlled modifications in secure applications.
The technical implementation of this vulnerability exploits the merge-deep module's failure to properly sanitize or validate prototype properties during object merging operations. When the module processes user-provided data structures, it inadvertently allows malicious input to modify the prototype chain of the Object constructor itself. This occurs because the module does not implement proper prototype validation or isolation mechanisms, allowing attackers to inject malicious properties through prototype pollution attacks that persist across all object instances in the application's memory space.
The operational impact of CVE-2018-3722 extends far beyond simple data corruption, as it creates persistent backdoors and attack vectors that can compromise entire application architectures. Once an attacker successfully pollutes the Object prototype, any subsequent object creation or property access may be influenced by the maliciously injected properties, potentially leading to arbitrary code execution, privilege escalation, or data exfiltration. This vulnerability is particularly dangerous because it affects the fundamental object model of javascript applications, making it difficult to detect and remediate without complete application rearchitecture.
Security practitioners should implement immediate mitigations including updating to merge-deep version 3.0.1 or later, which addresses the prototype pollution vulnerability through proper prototype validation. Organizations must also consider implementing prototype pollution detection tools and runtime protections that monitor for unauthorized prototype modifications. The vulnerability aligns with ATT&CK technique T1059.007 for JavaScript, where attackers leverage prototype pollution to achieve persistent access and code execution within node.js environments, making this issue particularly relevant for modern web application security assessments and penetration testing procedures.