CVE-2016-0753 in Ruby on Rails
Summary
by MITRE
Active Model in Ruby on Rails 4.1.x before 4.1.14.1, 4.2.x before 4.2.5.1, and 5.x before 5.0.0.beta1.1 supports the use of instance-level writers for class accessors, which allows remote attackers to bypass intended validation steps via crafted parameters.
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Analysis
by VulDB Data Team • 07/06/2022
The vulnerability identified as CVE-2016-0753 represents a critical security flaw in the Ruby on Rails framework that affects multiple version ranges including 4.1.x before 4.1.14.1, 4.2.x before 4.2.5.1, and 5.x before 5.0.0.beta1.1. This issue stems from the Active Model component's improper handling of instance-level writers for class accessors, creating a significant bypass opportunity for malicious actors. The flaw specifically exploits the framework's validation mechanisms, allowing attackers to manipulate object state through carefully crafted parameters that would normally be rejected by the validation layer.
The technical root cause of this vulnerability lies in how Ruby on Rails processes parameter assignment when dealing with class accessors that have instance-level writers defined. When developers define class accessors with instance-level writers, the framework should properly validate that these assignments occur within the intended scope and respect the validation constraints. However, the vulnerability allows attackers to bypass these validation steps by crafting specific parameter values that exploit the interaction between instance-level writers and class-level accessors. This creates a scenario where malicious inputs can modify object attributes without triggering the expected validation checks that should occur during parameter assignment.
From an operational impact perspective, this vulnerability enables remote attackers to perform unauthorized modifications to application data and object states. Attackers can leverage this bypass to manipulate validation rules that are designed to protect against invalid data entry, potentially leading to data corruption, unauthorized access to protected resources, or exploitation of other security controls that depend on proper validation. The vulnerability is particularly dangerous because it operates at the core framework level, meaning that applications built on affected versions of Ruby on Rails are susceptible to this attack regardless of the specific application logic or additional security measures implemented by developers. This makes the impact widespread and potentially devastating for organizations relying on vulnerable Rails applications.
The security implications of CVE-2016-0753 align with CWE-284, which addresses improper access control in software systems, and can be categorized under ATT&CK technique T1078 for valid accounts and T1566 for credential stuffing, as the vulnerability enables attackers to manipulate object states that should be protected by validation mechanisms. Organizations should immediately upgrade to the patched versions of Ruby on Rails to remediate this vulnerability, with specific version requirements including Rails 4.1.14.1, 4.2.5.1, and 5.0.0.beta1.1. Additionally, developers should review their application code to ensure that they are not inadvertently creating class accessors with instance-level writers that could be exploited, and implement proper input validation at multiple layers of their applications. The vulnerability demonstrates the importance of thorough security testing of framework components and the potential for seemingly minor implementation details to create significant security risks in web applications.