CVE-2021-23402 in record-like-deep-assign
Summary
by MITRE • 07/02/2021
All versions of package record-like-deep-assign are vulnerable to Prototype Pollution via the main functionality.
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Analysis
by VulDB Data Team • 07/09/2021
The vulnerability identified as CVE-2021-23402 affects the record-like-deep-assign package, which is susceptible to prototype pollution attacks through its core functionality. This type of vulnerability occurs when an attacker can manipulate the prototype of an object, potentially leading to arbitrary code execution or other malicious behaviors. The issue is particularly concerning because it affects all versions of the package, indicating a persistent flaw that has not been addressed through version updates. Prototype pollution vulnerabilities arise when applications fail to properly validate or sanitize user input before using it to modify object prototypes, creating a pathway for attackers to inject malicious properties into the prototype chain. The vulnerability can be exploited when the package processes data that originates from untrusted sources, allowing attackers to pollute the prototype of objects and potentially alter the behavior of the application. This flaw directly relates to CWE-471, which defines the weakness of "Modification of Assumed-Immutable Data", and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: JavaScript", as the exploitation can lead to execution of arbitrary JavaScript code. The attack vector typically involves providing malicious input that gets processed by the vulnerable package, which then modifies the prototype of objects in unexpected ways. This can result in the application behaving differently than intended, potentially allowing attackers to gain unauthorized access or manipulate application logic. The impact extends beyond simple data corruption, as prototype pollution can enable more sophisticated attacks such as bypassing security controls or causing denial of service conditions.
The technical implementation of this vulnerability stems from inadequate input validation within the deep assignment functionality of the record-like-deep-assign package. When the package processes objects that contain properties with special keys such as constructor or _proto_, it fails to sanitize these inputs properly, allowing attackers to inject properties that modify the prototype chain. This flaw is particularly dangerous because JavaScript prototypes are shared across all instances of objects, meaning that pollution of a prototype affects the entire application. The vulnerability can be exploited through various means including API endpoints, file uploads, or any input mechanism that passes data through the affected package. Attackers can craft payloads that contain prototype-polluting properties, which when processed by the vulnerable code, can alter the behavior of core JavaScript objects and potentially enable code execution. The exploitability is enhanced by the fact that many applications use deep assignment libraries to merge configuration objects or process user data, making the attack surface wide and potentially affecting numerous applications. This vulnerability also intersects with CWE-345, "Insufficient Verification of Data Authenticity", as it demonstrates how unverified data can be used to manipulate critical application components. The exploitation pattern aligns with ATT&CK technique T1211 for "Exploitation for Privilege Escalation" when the prototype pollution leads to elevated privileges within the application context.
The operational impact of CVE-2021-23402 extends beyond immediate security concerns to potentially compromise entire application ecosystems that rely on the vulnerable package. Organizations using this package in their applications face significant risk of unauthorized access, data manipulation, or service disruption. The vulnerability's persistence across all versions means that organizations must urgently assess their dependency trees to identify affected applications and implement immediate mitigations. The exploitation can lead to various attack scenarios including but not limited to bypassing authentication mechanisms, manipulating application configuration, or creating backdoor access points. The attack surface is particularly wide as the package is likely used in various application contexts including web servers, microservices, and backend systems. Organizations may experience cascading effects if the vulnerability is present in core libraries that other components depend upon, potentially affecting multiple applications within the same ecosystem. The vulnerability also creates challenges for incident response teams as it may not be immediately apparent which applications are affected, requiring comprehensive dependency analysis and vulnerability scanning. The remediation process requires careful consideration of the package's usage within applications, as complete replacement may not always be feasible. Organizations should also implement monitoring to detect potential exploitation attempts and establish procedures for rapid response to any signs of compromise.
Mitigation strategies for CVE-2021-23402 should prioritize immediate actions to reduce the attack surface and prevent exploitation. The most effective approach involves replacing the vulnerable package with a secure alternative or updating to a patched version if available. Organizations should conduct thorough dependency audits to identify all applications using the affected package and prioritize remediation based on risk assessment. Input validation and sanitization should be implemented at multiple layers to prevent malicious data from reaching the vulnerable code paths, particularly focusing on any user-provided data that gets processed by deep assignment functions. The implementation of Content Security Policy headers and other web application security measures can provide additional defense-in-depth. Regular security scanning and monitoring of dependency trees should be established to prevent future vulnerabilities from being introduced through third-party packages. Organizations should also consider implementing automated vulnerability detection tools that can identify and alert on the presence of known vulnerable packages. For environments where immediate replacement is not feasible, temporary workarounds such as implementing strict input validation, using proxy layers to sanitize data, or implementing application-level protections can provide interim security. The remediation process should include comprehensive testing to ensure that the mitigation does not introduce new issues or break existing functionality. Additionally, organizations should review their software supply chain security practices to improve identification and handling of vulnerable dependencies in the future, including implementing policies for regular dependency updates and vulnerability assessments.