CVE-2002-0176 in Libsafe
Summary
by MITRE
The printf wrappers in libsafe 2.0-11 and earlier do not properly handle argument indexing specifiers, which could allow attackers to exploit certain function calls through arguments that are not verified by libsafe.
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Analysis
by VulDB Data Team • 06/17/2024
The vulnerability described in CVE-2002-0176 resides within the libsafe library version 2.0-11 and earlier implementations, specifically affecting the printf wrapper functions that are designed to provide enhanced security against buffer overflow attacks. This flaw represents a critical weakness in the library's argument handling mechanism where the printf wrappers fail to properly process argument indexing specifiers, creating potential pathways for exploitation that bypass the intended security protections. The issue stems from the library's inability to correctly validate and process format string arguments that contain indexing specifiers, which are used to reference specific arguments in a variadic function call.
The technical implementation flaw manifests when the printf wrapper functions encounter format strings containing argument indexing specifiers such as %1$s, %2$d, or similar constructs that explicitly reference arguments by position rather than by order. In normal operation, these specifiers should be properly parsed and validated to ensure that the referenced arguments exist and are properly formatted. However, the libsafe library fails to adequately verify these indexed arguments, allowing attackers to craft malicious input that can manipulate the function call stack or access memory locations that should remain protected. This vulnerability operates at the intersection of format string vulnerabilities and library security mechanisms, creating a scenario where the very security features designed to prevent exploitation become the vector for successful attacks.
The operational impact of this vulnerability extends beyond simple buffer overflow protection failures, as it fundamentally undermines the security model that libsafe was designed to enforce. When attackers can bypass the argument validation mechanisms, they gain the ability to manipulate the execution flow of programs that rely on libsafe for security protection, potentially leading to arbitrary code execution, information disclosure, or denial of service conditions. The vulnerability is particularly dangerous because it affects the core printf wrapper functionality that many applications depend upon for secure string formatting operations, meaning that exploitation could compromise multiple applications simultaneously. This represents a classic case of security through obscurity failing, where the library's defensive mechanisms are subverted by insufficient input validation.
Mitigation strategies for this vulnerability require immediate attention from system administrators and developers who have deployed libsafe 2.0-11 or earlier versions. The most effective solution involves upgrading to a patched version of libsafe that properly handles argument indexing specifiers and implements comprehensive validation of all format string arguments. Organizations should also conduct thorough audits of their applications to identify any reliance on potentially vulnerable printf wrapper functions and implement additional input validation measures. From a defensive perspective, this vulnerability aligns with attack patterns documented in the attack technique matrix where adversaries exploit library-level security flaws to bypass application-level protections. The issue demonstrates the importance of proper validation of all input parameters, particularly in security libraries where incomplete implementation of core functionality can create dangerous attack vectors. This vulnerability also highlights the necessity of following established security standards such as those defined in the CWE database, specifically CWE-134 which addresses format string vulnerabilities, and reinforces the principles of secure coding practices that emphasize the importance of comprehensive input validation and proper argument handling in security-critical libraries.