CVE-2018-16476 in Active Job
Summary
by MITRE
A Broken Access Control vulnerability in Active Job versions >= 4.2.0 allows an attacker to craft user input which can cause Active Job to deserialize it using GlobalId and give them access to information that they should not have.
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Analysis
by VulDB Data Team • 06/12/2023
The vulnerability identified as CVE-2018-16476 represents a critical broken access control flaw within Ruby on Rails Active Job framework versions 4.2.0 and later. This weakness stems from improper input validation during the deserialization process, specifically when Active Job processes user-supplied data through the GlobalId library. The vulnerability creates a path for unauthorized information disclosure by allowing attackers to manipulate serialized objects that are subsequently processed by the framework's job queue system.
The technical exploitation of this vulnerability occurs when user input is passed through Active Job's serialization mechanism without adequate sanitization or access control checks. The GlobalId library, which is designed to provide unique identifiers for objects across different systems, becomes a vector for privilege escalation when combined with insufficient validation of serialized data. Attackers can craft malicious serialized payloads that, when processed by Active Job, result in unauthorized access to data that should be restricted to specific user roles or permissions. This flaw operates at the intersection of serialization security and access control mechanisms, creating a scenario where the framework's intended object persistence features become weaponized against the application's security boundaries.
The operational impact of CVE-2018-16476 extends beyond simple information disclosure to potentially enable more severe attacks including privilege escalation and data exfiltration. Organizations running affected Rails applications face significant risk as attackers can exploit this vulnerability to access sensitive user data, system information, or administrative resources that should be protected by proper access controls. The vulnerability affects applications that utilize Active Job's background processing capabilities, making it particularly dangerous for web applications that handle sensitive data or require robust security controls. The attack surface is broad since Active Job is commonly used across various Rails applications for processing tasks asynchronously, increasing the potential exposure of affected systems.
Mitigation strategies for this vulnerability require immediate action including upgrading to patched versions of Ruby on Rails Active Job, typically version 5.2.1 or later which address the deserialization issue. Organizations should implement input validation and sanitization measures to prevent malicious data from reaching the serialization layer, while also reviewing their access control policies to ensure proper authorization checks are in place. The vulnerability aligns with CWE-284 (Improper Access Control) and can be mapped to ATT&CK technique T1078 (Valid Accounts) and T1566 (Phishing) as attackers may leverage this flaw to escalate privileges or gain unauthorized access to systems. Additional protective measures include implementing proper monitoring and logging of job queue activities, conducting regular security assessments of serialized data handling, and ensuring that all applications are running supported versions of the framework to minimize exposure to known vulnerabilities.