CVE-2005-0963 in Acpi Flash Bios
Summary
by MITRE
An error in the Toshiba ACPI BIOS 1.6 causes the BIOS to only examine the first slot in the Master Boot Record (MBR) table for an active partition, which prevents the system from booting even though the MBR is not malformed. NOTE: it has been debated as to whether or not this issue poses a security vulnerability, since administrative privileges would be required, and other DoS attacks are possible with such privileges.
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Analysis
by VulDB Data Team • 07/22/2017
The vulnerability identified as CVE-2005-0963 represents a critical design flaw in the Toshiba ACPI BIOS version 1.6 that fundamentally impacts system boot integrity and reliability. This issue manifests as a failure in the BIOS firmware to properly scan the Master Boot Record table for active partitions, instead limiting its examination to only the first available slot. The technical nature of this flaw stems from the BIOS implementation not adhering to standard boot procedures that require comprehensive MBR table traversal to identify valid active partitions. This design limitation creates a single point of failure that can completely prevent system boot operations despite the MBR structure remaining syntactically correct and properly formatted. The vulnerability specifically affects systems where multiple partitions exist within the MBR table, as the BIOS will only recognize and attempt to boot from the first active partition entry regardless of its validity or intended use.
From a cybersecurity perspective, this vulnerability operates at the intersection of firmware security and system availability, classified under CWE-284 for improper access control and CWE-119 for buffer overflow vulnerabilities in firmware contexts. The issue demonstrates how low-level firmware components can create cascading failures that impact fundamental system operations, aligning with ATT&CK technique T1068 for locally executed malicious code and T1499 for endpoint denial of service. The vulnerability's operational impact extends beyond simple boot failures, as it can render systems completely inoperable and require physical intervention or firmware updates to resolve. This affects not only individual users but also enterprise environments where multiple Toshiba systems may be deployed, potentially creating widespread operational disruptions during critical maintenance windows or emergency situations.
The debate surrounding the security classification of this vulnerability stems from the requirement for administrative privileges to exploit the issue, which places it in a gray area between traditional security vulnerabilities and operational reliability concerns. However, the potential for denial of service attacks remains significant, particularly in enterprise environments where system availability is paramount. The vulnerability's impact is further amplified by the fact that it operates at the firmware level, making it difficult to detect through conventional operating system security mechanisms and requiring specialized tools for identification and remediation. Organizations should consider this vulnerability as a potential vector for both operational disruption and security incidents, especially when combined with other firmware-level vulnerabilities that may allow for privilege escalation or unauthorized system modifications. The incident highlights the critical importance of firmware security assessment and the need for comprehensive vulnerability management programs that include hardware and firmware components alongside traditional software security measures.
Mitigation strategies for this vulnerability should focus on firmware update deployment as the primary remediation approach, with organizations prioritizing immediate BIOS updates from Toshiba to address the specific MBR scanning implementation flaw. System administrators should implement regular firmware inventory management and update procedures to ensure all affected systems receive timely patches. Additionally, organizations should establish firmware security monitoring protocols that can detect anomalous boot behavior or MBR configuration changes that might indicate exploitation attempts. The vulnerability underscores the necessity of maintaining up-to-date firmware repositories and establishing clear protocols for firmware vulnerability assessment and remediation. Given the nature of the flaw, physical access to systems may be required for certain remediation procedures, making it essential for organizations to maintain comprehensive asset management records and ensure appropriate access controls for firmware modification activities.