CVE-2018-16092 in System Management Module
Summary
by MITRE
In System Management Module (SMM) versions prior to 1.06, the FFDC feature includes the collection of SMM system files containing sensitive information; notably, the SMM user account credentials and the system shadow file.
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Analysis
by VulDB Data Team • 04/15/2020
The vulnerability described in CVE-2018-16092 represents a critical security flaw within the System Management Module (SMM) firmware component of certain computer systems. SMM is a privileged execution environment that operates below the operating system level, providing low-level system management functions and maintaining system security through its elevated privileges. The FFDC (First Failure Data Collection) feature within these SMM implementations was designed to gather diagnostic information during system failures, but it contained a significant design flaw that exposed sensitive system data. This vulnerability affects SMM versions prior to 1.06, indicating that the issue was present in older firmware implementations that lacked proper data sanitization and access controls. The flaw directly violates fundamental security principles by allowing unauthorized access to critical system credentials and authentication data through a diagnostic feature that should only collect non-sensitive operational information.
The technical implementation of this vulnerability stems from inadequate data handling within the SMM's FFDC functionality. When system failures occur, the FFDC mechanism is intended to collect diagnostic data for troubleshooting purposes, but it fails to properly filter or sanitize the collected information. Specifically, the feature indiscriminately includes sensitive system files such as SMM user account credentials and the system shadow file in its data collection process. This represents a severe breakdown in information flow control and privilege separation, as the diagnostic collection process operates with the same elevated privileges as the SMM itself. The vulnerability manifests as a failure to properly isolate sensitive data from diagnostic collections, creating an information disclosure channel that bypasses normal operating system security controls. This flaw aligns with CWE-200 (Information Exposure) and CWE-210 (Privilege Escalation) categories, demonstrating how improper access control and information handling can create persistent security weaknesses.
The operational impact of this vulnerability extends far beyond typical software security flaws, as it affects the fundamental security architecture of computer systems at the firmware level. Attackers who can exploit this vulnerability gain access to SMM user credentials and system shadow files, which contain hashed passwords and authentication information that could be used for privilege escalation attacks. The implications are particularly severe because SMM operates below the operating system level, making detection and mitigation extremely difficult. This vulnerability creates a persistent backdoor that can be exploited by attackers with physical access to systems or those who can execute code within the SMM environment. The exposure of system shadow files particularly undermines the security of password-based authentication systems, as these files typically contain password hashes that can be subjected to offline password cracking attacks. This vulnerability directly maps to ATT&CK technique T1068 (Local Privilege Escalation) and T1003 (OS Credential Dumping) by providing unauthorized access to system authentication data through firmware-level mechanisms.
Mitigation strategies for this vulnerability require firmware-level updates and patches to properly implement data sanitization within the SMM's FFDC feature. System administrators should prioritize updating affected SMM firmware to version 1.06 or later, which contains the necessary fixes to prevent sensitive data collection. Additional mitigations include implementing secure boot mechanisms, disabling unnecessary diagnostic features when not actively needed, and monitoring for unusual SMM activity that might indicate exploitation attempts. Organizations should also consider implementing hardware security modules or trusted platform modules that can provide additional layers of protection against firmware-level attacks. The vulnerability highlights the importance of proper security testing and validation of firmware components, particularly those operating with elevated privileges. Regular firmware audits and vulnerability assessments should be conducted to identify similar issues in other system management modules. The incident underscores the need for comprehensive security controls throughout the entire system lifecycle, from hardware design through firmware implementation and operational deployment, as vulnerabilities at the firmware level can compromise entire system security architectures.