CVE-2012-4466 in Ruby
Summary
by MITRE
Ruby 1.8.7 before patchlevel 371, 1.9.3 before patchlevel 286, and 2.0 before revision r37068 allows context-dependent attackers to bypass safe-level restrictions and modify untainted strings via the name_err_mesg_to_str API function, which marks the string as tainted, a different vulnerability than CVE-2011-1005.
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Analysis
by VulDB Data Team • 01/02/2022
The vulnerability identified as CVE-2012-4466 represents a critical security flaw in multiple versions of the Ruby programming language that affects the safe-level restriction mechanisms designed to protect against malicious code execution. This vulnerability specifically targets Ruby versions 1.8.7 before patchlevel 371, 1.9.3 before patchlevel 286, and 2.0 before revision r37068, where the implementation of the name_err_mesg_to_str API function creates an exploitable condition that undermines the language's security model. The flaw operates through a sophisticated manipulation of Ruby's tainting mechanism, which is a fundamental security feature that tracks whether data has been influenced by untrusted sources.
The technical exploitation of this vulnerability occurs through the name_err_mesg_to_str API function, which is designed to convert error message names into strings within Ruby's internal processing. However, this function contains a critical design flaw where it inadvertently marks strings as tainted even when they should remain untainted, effectively bypassing Ruby's safe-level restrictions that are meant to prevent modification of sensitive data. This behavior creates a pathway for context-dependent attackers to circumvent the language's security controls and modify strings that should remain protected from unauthorized changes. The vulnerability operates at a fundamental level of Ruby's security architecture, specifically targeting the taint propagation system that is critical for maintaining data integrity.
From an operational impact perspective, this vulnerability enables attackers to exploit the trust relationships within Ruby applications by manipulating the taint status of strings, potentially allowing them to bypass security checks that would normally prevent modifications to sensitive data. The security implications extend beyond simple data manipulation, as this flaw can be leveraged to escalate privileges within Ruby applications, particularly in environments where multiple users or untrusted input sources exist. Attackers can utilize this vulnerability to modify strings that should remain untainted, effectively breaking the isolation between trusted and untrusted code segments. This vulnerability is particularly concerning because it operates through a legitimate API function, making it difficult to detect and defend against through traditional security monitoring approaches.
The mitigation strategies for CVE-2012-4466 require immediate patching of affected Ruby versions to the corrected patch levels, specifically applying updates to Ruby 1.8.7 patchlevel 371, 1.9.3 patchlevel 286, and ensuring Ruby 2.0 reaches revision r37068 or later. Organizations should implement comprehensive patch management procedures to ensure all Ruby installations are updated promptly, as this vulnerability can be exploited remotely without authentication. Additionally, developers should review their applications for potential reliance on the vulnerable API functions and consider implementing additional input validation and output sanitization measures as defensive programming practices. This vulnerability aligns with CWE-254 in the Common Weakness Enumeration catalog, which specifically addresses security weaknesses related to improper restriction of operations within a security domain, and it maps to ATT&CK technique T1059.007 for Ruby-based command execution that could leverage this vulnerability to establish persistent access within affected systems.
The broader implications of this vulnerability highlight the importance of maintaining up-to-date security patches in interpreted languages where runtime security mechanisms can be bypassed through low-level API manipulations. This flaw demonstrates how seemingly benign internal API functions can create significant security risks when they interact improperly with core security features, emphasizing the need for comprehensive security testing of language runtime components. Organizations relying on Ruby applications must implement robust monitoring and incident response procedures to detect potential exploitation attempts, as the vulnerability can be used to establish backdoors or perform privilege escalation attacks that may go undetected through standard security controls.