CVE-2021-23442 in cookiex-deep
Summary
by MITRE • 09/17/2021
This affects all versions of package @cookiex/deep. The global proto object can be polluted using the __proto__ object.
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Analysis
by VulDB Data Team • 09/22/2021
The vulnerability identified as CVE-2021-23442 represents a critical prototype pollution flaw within the @cookiex/deep package, affecting all versions of this npm module. This type of vulnerability falls under the category of prototype pollution attacks where an attacker can manipulate the prototype of JavaScript objects, leading to unpredictable behavior and potential security breaches. The issue specifically arises from the improper handling of the _proto_ property during object manipulation operations, allowing malicious input to alter the global Object.prototype object. When developers use this package in their applications, they inadvertently expose their code to potential exploitation through prototype pollution vectors.
The technical implementation of this vulnerability stems from the package's failure to properly sanitize or validate object properties when processing user input or external data. The _proto_ property in JavaScript serves as a mechanism to access and modify an object's prototype chain, but when this property becomes writable and is not properly restricted, attackers can inject malicious prototypes into the global object. This occurs because the package likely uses a method that directly assigns properties to objects without validating whether those properties correspond to prototype-polluting keywords like _proto_, constructor, or prototype. The flaw allows attackers to inject arbitrary code or manipulate object behavior by polluting the prototype chain of the global Object constructor, which affects all subsequent object instantiations.
The operational impact of this vulnerability extends far beyond simple code injection, potentially enabling attackers to achieve arbitrary code execution, bypass security controls, or manipulate application behavior at a fundamental level. When prototype pollution occurs in a global context, it can affect not just the specific application using the vulnerable package but also potentially compromise other modules or libraries that rely on the integrity of the global prototype chain. This vulnerability can be exploited in various attack scenarios including server-side prototype pollution, where the attacker can manipulate object properties to inject malicious code that executes when the application processes data. The implications are particularly severe in Node.js environments where prototype pollution can lead to privilege escalation, denial of service, or complete system compromise. This vulnerability aligns with CWE-471, which specifically addresses the issue of "Modification of Object Prototype Attributes" and represents a classic example of how improper input validation can lead to prototype pollution attacks.
Mitigation strategies for CVE-2021-23442 require immediate action to update the vulnerable package to a patched version or implement defensive programming practices. Organizations should prioritize updating their dependencies to versions that properly sanitize object properties and prevent prototype pollution through validation of input data. Developers must implement proper input validation and sanitization routines that explicitly check for and reject prototype-polluting keywords during object manipulation. The use of libraries like prototype-check or similar validation tools can help prevent malicious prototype pollution attempts. Additionally, implementing Content Security Policy headers and using secure coding practices such as avoiding direct property assignment to objects with user-controlled data can significantly reduce the risk. From an ATT&CK framework perspective, this vulnerability maps to T1059.006 for Node.js command injection and T1190 for exploit development, making it a critical target for security teams to address through both immediate patching and long-term defensive measures. Organizations should also consider implementing dependency monitoring solutions to detect and alert on vulnerable packages in their software supply chains, as this type of vulnerability can persist across multiple applications and environments.