CVE-2018-16089 in System Management Module
Summary
by MITRE
In System Management Module (SMM) versions prior to 1.06, a field in the header of SMM firmware update images is insufficiently sanitized, allowing post-authentication command injection on the SMM as the root user.
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Analysis
by VulDB Data Team • 04/15/2020
The vulnerability identified as CVE-2018-16089 resides within the System Management Module firmware component, which operates in a privileged execution environment below the operating system level. This SMM firmware serves as a critical subsystem responsible for low-level hardware management and system configuration tasks. The vulnerability specifically affects firmware versions prior to 1.06 and stems from inadequate input validation within the firmware update image header processing logic. The flaw manifests when the SMM firmware processes update images containing maliciously crafted header fields that are not properly sanitized before being utilized in subsequent operations.
The technical implementation of this vulnerability enables an authenticated attacker to inject arbitrary commands directly into the SMM execution context with root-level privileges. This represents a severe privilege escalation vector since the SMM operates with the highest privilege level possible within the system architecture, typically executing with full hardware access and system-level control. The insufficient sanitization of header fields allows attackers to manipulate the firmware update process in such a way that malicious commands are interpreted and executed within the SMM environment, effectively bypassing traditional operating system security controls and access restrictions.
The operational impact of this vulnerability extends beyond typical software exploitation scenarios due to the privileged nature of the SMM execution environment. An attacker who gains authentication access to the system can leverage this vulnerability to achieve persistent root-level control over the firmware itself, potentially enabling undetectable system compromise that survives operating system reinstallation or complete system reset. The SMM operates outside the normal operating system memory space and execution context, making traditional security monitoring tools ineffective against such attacks. This vulnerability aligns with CWE-77 and CWE-78 categories, representing command injection flaws in privileged execution environments. The attack vector follows patterns consistent with ATT&CK technique T1068, which involves exploiting legitimate credentials to execute malicious code in privileged contexts.
Mitigation strategies for CVE-2018-16089 primarily focus on firmware version updates to 1.06 or later, which contain proper sanitization mechanisms for header fields. Organizations should implement firmware integrity monitoring solutions to detect unauthorized modifications to SMM components and establish secure firmware update procedures with proper authentication and verification steps. Additionally, system administrators should consider implementing hardware-based security features such as Platform Trust Technology or Secure Boot mechanisms that can prevent execution of unsigned or modified firmware components. Regular firmware vulnerability assessments and supply chain security reviews become essential practices to prevent exploitation of similar vulnerabilities in other firmware components that may operate within the same privileged execution contexts.