CVE-2011-2929 in Ruby on Rails
Summary
by MITRE
The template selection functionality in actionpack/lib/action_view/template/resolver.rb in Ruby on Rails 3.0.x before 3.0.10 and 3.1.x before 3.1.0.rc6 does not properly handle glob characters, which allows remote attackers to render arbitrary views via a crafted URL, related to a "filter skipping vulnerability."
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Analysis
by VulDB Data Team • 11/18/2021
The vulnerability described in CVE-2011-2929 represents a critical security flaw in the Ruby on Rails web application framework that specifically affects the template resolution mechanism. This issue resides within the actionpack component at the path actionview/lib/action_view/template/resolver.rb and impacts versions prior to 3.0.10 and 3.1.0.rc6. The flaw stems from insufficient validation of glob characters within template selection functionality, creating a path traversal condition that can be exploited by remote attackers to access unauthorized view files.
The technical implementation of this vulnerability exploits the way Rails processes template paths when resolving view requests. When a URL contains glob characters such as asterisks or other pattern matching symbols, the template resolver fails to properly sanitize or validate these inputs before using them to locate template files. This improper handling allows attackers to craft malicious URLs that bypass normal template resolution logic and directly reference view files outside the intended application scope. The vulnerability operates at the core of Rails' view rendering pipeline, where template paths are processed and resolved before being rendered to end users.
The operational impact of this vulnerability is severe as it enables remote code execution through view rendering, allowing attackers to potentially access sensitive application views, configuration files, or other unauthorized resources. This creates a significant risk for applications using affected Rails versions, as the exploitation can lead to information disclosure, unauthorized access to application components, and potential escalation to full system compromise. The vulnerability specifically targets the template resolution mechanism rather than direct code execution, making it particularly insidious as it can be leveraged to render arbitrary views that may contain sensitive data or application logic.
From a cybersecurity perspective, this vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and represents a classic example of input validation failure in web application frameworks. The issue falls under the ATT&CK technique T1059.001 (Command and Scripting Interpreter: PowerShell) when exploited through view rendering, as attackers can potentially inject malicious content into rendered templates. The vulnerability demonstrates how seemingly benign template selection functionality can become a vector for privilege escalation and data exfiltration when proper input sanitization is absent.
Organizations affected by this vulnerability should immediately upgrade to Rails versions 3.0.10 or 3.1.0.rc6, which contain the necessary patches to address the glob character handling issue. Additionally, implementing proper input validation at the application level, monitoring for unusual URL patterns, and employing web application firewalls can provide additional defense-in-depth measures. The patch addresses the core issue by implementing proper sanitization of glob characters in template paths and ensuring that all template resolution operations properly validate input before processing, preventing attackers from manipulating the template resolution logic to access unauthorized resources.