CVE-2016-5729 in BIOS EFI Driver
Summary
by MITRE
Lenovo BIOS EFI Driver allows local administrators to execute arbitrary code with System Management Mode (SMM) privileges via unspecified vectors.
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Analysis
by VulDB Data Team • 02/15/2019
The vulnerability identified as CVE-2016-5729 represents a critical security flaw within Lenovo's BIOS EFI driver implementation that fundamentally undermines system security through privilege escalation. This issue affects Lenovo computers that utilize EFI firmware and specifically targets the System Management Mode execution environment where the BIOS driver operates with the highest privilege level. The vulnerability allows local administrators to leverage unspecified attack vectors to execute arbitrary code with SMM privileges, effectively bypassing standard operating system security controls and gaining access to the most privileged execution context available to firmware components.
The technical nature of this vulnerability stems from insufficient input validation and privilege control mechanisms within the EFI driver code that handles SMM operations. When a local administrator executes specific commands or loads malicious payloads through the vulnerable driver interface, the system grants execution privileges that extend into the System Management Mode realm. This mode operates outside the normal operating system execution context and has direct access to system memory, hardware components, and can manipulate system behavior at the lowest levels. The unspecified vectors suggest that multiple attack surfaces within the EFI driver implementation may be exploitable, making the vulnerability particularly dangerous as attackers can potentially identify various paths to achieve the same privilege escalation outcome.
The operational impact of this vulnerability is severe and far-reaching across enterprise and consumer environments. Organizations utilizing affected Lenovo systems face significant risk of persistent malware installation that can survive operating system reinstallation, hardware replacement, or complete system recovery procedures. Attackers can leverage this vulnerability to establish rootkits that maintain persistence at the firmware level, making detection and removal extremely difficult. The privilege escalation to SMM level allows attackers to manipulate system firmware, modify boot processes, intercept keystrokes, monitor network traffic, and potentially compromise the entire system infrastructure. This vulnerability directly violates fundamental security principles by enabling unauthorized code execution with the highest possible system privileges, essentially providing attackers with complete control over the affected systems.
Mitigation strategies for CVE-2016-5729 must address both immediate remediation and long-term security posture improvements. Organizations should prioritize applying official firmware updates from Lenovo that address the specific EFI driver vulnerability and ensure that BIOS firmware is kept current with the latest security patches. System administrators should implement strict access controls and privilege management policies, limiting local administrator access to systems where possible. The vulnerability aligns with CWE-284 which addresses improper access control in system components, and represents a significant concern under ATT&CK framework's privilege escalation techniques where attackers seek to gain elevated system privileges. Additionally, organizations should consider implementing firmware integrity monitoring solutions and regular security assessments to detect potential exploitation attempts. Network segmentation and endpoint detection and response systems should be deployed to monitor for suspicious activities that may indicate exploitation of this vulnerability, as traditional security controls may be insufficient to detect SMM-level attacks that operate outside normal operating system monitoring capabilities.