CVE-2013-4285 in PAM S
Summary
by MITRE
A certain Gentoo patch for the PAM S/Key module does not properly clear credentials from memory, which allows local users to obtain sensitive information by reading system memory.
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Analysis
by VulDB Data Team • 05/12/2026
The vulnerability identified as CVE-2013-4285 resides within the PAM S/Key module implementation in Gentoo Linux systems, representing a critical security flaw in credential handling mechanisms. This issue specifically affects the Secure Remote Password authentication method that relies on S/Key one-time passwords for enhanced security. The vulnerability stems from improper memory management practices within the PAM module where authentication credentials and sensitive data are not adequately cleared from memory after use, leaving residual information accessible to unauthorized local processes. This flaw demonstrates a fundamental weakness in how the module handles sensitive information during authentication cycles, creating a persistent security risk that extends beyond the immediate authentication event.
The technical exploitation of this vulnerability occurs through local memory inspection techniques where malicious processes can access memory segments previously occupied by the PAM S/Key module. The flaw constitutes a memory corruption issue that directly violates proper secure coding practices and represents a classic example of insufficient memory sanitization. When the PAM module processes authentication requests, it stores sensitive data including one-time passwords and cryptographic keys in memory locations that remain accessible to other processes running with the same privileges. This memory leakage creates an information disclosure vulnerability that can be exploited by local attackers with minimal privileges to extract potentially sensitive authentication data from system memory. The vulnerability specifically aligns with CWE-128, which addresses insufficient clearing of sensitive data from memory, and reflects poor memory management practices that compromise system security.
From an operational perspective, this vulnerability presents significant risk to systems relying on PAM S/Key authentication, particularly in environments where local privilege escalation is a concern. The impact extends beyond simple information disclosure as attackers can potentially reconstruct authentication sequences and exploit the leaked information for further attacks. The vulnerability is particularly concerning because it affects the core authentication infrastructure of the system, making it a prime target for attackers seeking to escalate privileges or compromise additional system resources. Local users with access to the system can leverage this flaw to extract sensitive information that may include cryptographic keys, authentication tokens, or other credentials that could be used to bypass authentication mechanisms. The attack surface is broad since any process running with sufficient privileges can potentially access this leaked memory, creating a persistent threat vector that remains active throughout the system's operation.
Mitigation strategies for CVE-2013-4285 require immediate patching of the affected PAM S/Key module implementation in Gentoo systems, with administrators prioritizing the application of vendor-provided security updates. The recommended approach involves implementing proper memory clearing mechanisms that ensure all sensitive data is completely overwritten before memory segments are released back to the system. System administrators should also consider implementing additional monitoring for unauthorized memory access patterns and establish regular security audits to detect potential exploitation attempts. The vulnerability highlights the importance of following secure coding practices and proper memory management in authentication modules, aligning with ATT&CK technique T1003.001 for OS credential dumping and T1059.003 for command and scripting interpreter usage patterns. Organizations should also implement principle of least privilege controls to limit the potential impact of such vulnerabilities and consider adopting more robust authentication mechanisms that do not rely on potentially vulnerable memory handling practices. Regular security assessments and penetration testing should be conducted to identify similar memory management issues in other system components and ensure comprehensive protection against credential leakage vulnerabilities.