CVE-2016-2097 in Ruby on Rails
Summary
by MITRE
Directory traversal vulnerability in Action View in Ruby on Rails before 3.2.22.2 and 4.x before 4.1.14.2 allows remote attackers to read arbitrary files by leveraging an application's unrestricted use of the render method and providing a .. (dot dot) in a pathname. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-0752.
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Analysis
by VulDB Data Team • 07/12/2022
The CVE-2016-2097 vulnerability represents a critical directory traversal flaw within the Action View component of Ruby on Rails frameworks. This vulnerability affects versions prior to 3.2.22.2 and 4.x prior to 4.1.14.2, exposing applications to remote code execution risks through improper path validation mechanisms. The flaw specifically leverages the render method's unrestricted handling of user-supplied pathnames, allowing attackers to navigate beyond intended directories and access arbitrary files on the server filesystem. This vulnerability is particularly concerning as it stems from an incomplete remediation of CVE-2016-0752, indicating a pattern of insufficient security fixes that leave applications vulnerable to sophisticated attacks.
The technical implementation of this vulnerability exploits the fundamental weakness in how Ruby on Rails processes file paths during rendering operations. When applications utilize the render method with user-controllable input, the framework fails to properly sanitize or validate path components that contain directory traversal sequences such as "..". Attackers can manipulate these parameters to traverse up the directory structure and access sensitive files including configuration files, database credentials, application source code, and other privileged resources. The vulnerability operates at the application layer and requires no special privileges beyond network access to the affected web application, making it particularly dangerous in environments where applications are publicly accessible.
The operational impact of CVE-2016-2097 extends far beyond simple information disclosure, as successful exploitation can lead to complete system compromise. Attackers can leverage this vulnerability to read sensitive configuration files containing database passwords, API keys, and cryptographic secrets that would otherwise remain protected. Additionally, the ability to access application source code provides attackers with insights into application architecture, business logic, and potential additional vulnerabilities. In some cases, this information disclosure can serve as a stepping stone for further exploitation, potentially leading to privilege escalation, data corruption, or complete system takeover. The vulnerability's presence in widely-used Ruby on Rails versions means that numerous production applications across various industries were potentially exposed to this risk.
Organizations affected by CVE-2016-2097 should immediately implement the recommended security patches to upgrade their Ruby on Rails frameworks to versions 3.2.22.2 or 4.1.14.2 and later. Beyond patching, defensive measures should include implementing input validation for all user-supplied path parameters, employing web application firewalls to detect and block suspicious path traversal attempts, and conducting comprehensive security assessments of application code to identify similar vulnerabilities. The vulnerability aligns with CWE-22 Directory Traversal and maps to ATT&CK technique T1083 File and Directory Discovery, emphasizing the need for robust access controls and least privilege principles. Security teams should also establish monitoring procedures to detect unusual file access patterns and implement proper logging of file operations to aid in incident response and forensic analysis. Regular security training for development teams is crucial to prevent similar vulnerabilities in future application development cycles.