CVE-2011-1004 in Ruby
Summary
by MITRE
The FileUtils.remove_entry_secure method in Ruby 1.8.6 through 1.8.6-420, 1.8.7 through 1.8.7-330, 1.8.8dev, 1.9.1 through 1.9.1-430, 1.9.2 through 1.9.2-136, and 1.9.3dev allows local users to delete arbitrary files via a symlink attack.
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Analysis
by VulDB Data Team • 03/19/2021
The vulnerability identified as CVE-2011-1004 represents a critical security flaw in Ruby's FileUtils.remove_entry_secure method that affects multiple versions of the Ruby programming language from 1.8.6 through 1.9.3dev. This vulnerability stems from insufficient handling of symbolic links during file removal operations, creating a path traversal attack vector that allows malicious actors to delete files outside the intended directory scope. The flaw specifically manifests when the remove_entry_secure method processes directory entries that contain symbolic links, failing to properly validate or resolve these links before attempting deletion operations. This vulnerability directly maps to CWE-22 Path Traversal and CWE-59 Improper Link Resolution, as it involves improper handling of symbolic links and directory traversal mechanisms. The issue enables attackers to exploit the method's behavior by creating a malicious symlink structure that points to sensitive system files or directories outside the intended target location.
The technical exploitation of this vulnerability requires an attacker to have local access to the system and the ability to create symbolic links within the directory structure that the vulnerable Ruby application operates on. When the remove_entry_secure method processes a directory containing a symbolic link, it follows the link without proper validation and attempts to delete the target file that the link points to, rather than deleting the symbolic link itself. This behavior creates a scenario where an attacker can manipulate the application's file removal process to delete arbitrary files on the system, potentially including system-critical files or files owned by other users. The vulnerability is particularly dangerous because it operates at the filesystem level and can be leveraged by attackers to perform unauthorized file deletions, potentially leading to system instability, data loss, or privilege escalation. The attack vector specifically targets the insecure handling of directory entries in Ruby applications that utilize the FileUtils module for file management operations, making it a widespread concern across applications that depend on these Ruby versions.
The operational impact of CVE-2011-1004 extends beyond simple file deletion capabilities, as it represents a fundamental flaw in how Ruby applications handle file system operations that can be exploited in various attack scenarios. Applications that process user-supplied directory paths or perform automated cleanup operations using the FileUtils.remove_entry_secure method become vulnerable to this attack, particularly in multi-user environments where different applications or users share the same system resources. The vulnerability can be exploited to delete critical system files, configuration files, or files belonging to other users, potentially causing system crashes, service disruption, or data corruption. From an attack framework perspective, this vulnerability aligns with ATT&CK technique T1059 Command and Scripting Interpreter and T1070 Indicator Removal on Host, as it enables attackers to manipulate file systems and potentially remove evidence of their activities. The impact is particularly severe in web applications or system tools that rely on Ruby for file management, as these applications may be exposed to untrusted input that can trigger the vulnerable code path. Organizations running affected Ruby versions are at risk of unauthorized file deletion attacks that could compromise system integrity and availability.
Mitigation strategies for CVE-2011-1004 focus primarily on upgrading to patched versions of Ruby that address the symbolic link handling issue in the FileUtils.remove_entry_secure method. System administrators should prioritize updating Ruby installations to versions 1.8.7-331, 1.9.1-431, 1.9.2-137, or later releases that contain the necessary security fixes. Additionally, applications should implement proper input validation and sanitization when processing directory paths, particularly when dealing with user-supplied input that might be used in file removal operations. Security measures should include restricting the ability to create symbolic links in directories where file removal operations occur, implementing proper file system permissions, and using alternative file removal methods that do not rely on the vulnerable FileUtils.remove_entry_secure approach. Organizations should also consider implementing monitoring and logging for file system operations, particularly those involving directory removals, to detect potential exploitation attempts. The vulnerability highlights the importance of secure coding practices in file system operations and the necessity of proper validation of symbolic links and directory entries before performing destructive operations, aligning with security best practices outlined in the OWASP Top Ten and NIST cybersecurity frameworks.