CVE-2018-16490 in mpath
Summary
by MITRE
A prototype pollution vulnerability was found in module mpath <0.5.1 that allows an attacker to inject arbitrary properties onto Object.prototype.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/07/2020
The vulnerability identified as CVE-2018-16490 represents a critical prototype pollution flaw within the mpath module version 0.5.1 and earlier. This issue resides in the module's handling of object property assignment operations, where improper validation allows malicious input to be interpreted as property definitions that get injected into the Object.prototype chain. The vulnerability stems from a lack of proper input sanitization during the processing of nested object paths, enabling attackers to manipulate the prototype of all objects in the JavaScript runtime environment.
Prototype pollution vulnerabilities occur when an application fails to properly validate or sanitize user-supplied input that is used to set object properties. In this specific case, the mpath module processes object path strings to navigate nested object structures, but does not adequately check whether the input contains malicious property names that could alter the prototype chain. When an attacker provides crafted input containing special characters or sequences that are interpreted as property definitions, the module inadvertently creates properties on Object.prototype, which then become accessible to all objects in the application's scope.
The operational impact of this vulnerability is significant as it can lead to various downstream security issues including but not limited to denial of service conditions, privilege escalation, and arbitrary code execution. When properties are injected into Object.prototype, they become available to all objects that inherit from it, potentially allowing attackers to manipulate core object behaviors, bypass security controls, or cause unexpected application behavior. This vulnerability can be particularly dangerous in server-side JavaScript environments where the prototype pollution can affect the entire application runtime, especially in applications that rely heavily on object manipulation and dynamic property access.
The technical flaw manifests when the mpath module processes user-controlled input without proper validation, allowing attackers to inject properties that pollute the prototype chain. This typically occurs when the module uses methods like Object.assign or direct property assignment without checking for potentially malicious property names. The vulnerability is classified under CWE-471 as "Modification of Externally-Controllable Resource" and can be mapped to ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript" as it enables attackers to manipulate JavaScript runtime behavior through prototype manipulation.
Mitigation strategies for this vulnerability include upgrading to mpath version 0.5.1 or later, which contains proper input validation and sanitization mechanisms. Organizations should also implement strict input validation at all points where user-supplied data is processed, particularly when dealing with nested object path operations. Additional protective measures include using secure coding practices such as avoiding direct property assignment from untrusted input, implementing prototype pollution detection mechanisms, and regularly auditing third-party dependencies for known vulnerabilities. Security teams should also consider implementing runtime monitoring to detect anomalous prototype modifications and establish proper dependency management practices to ensure timely patching of vulnerable components.