CVE-2017-3775 in System X Server BIOS
Summary
by MITRE
Some Lenovo System x server BIOS/UEFI versions, when Secure Boot mode is enabled by a system administrator, do not properly authenticate signed code before booting it. As a result, an attacker with physical access to the system could boot unsigned code.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 02/02/2020
The vulnerability identified as CVE-2017-3775 affects Lenovo System x server BIOS/UEFI implementations and represents a critical failure in the secure boot mechanism that is fundamental to modern hardware security architectures. This weakness specifically manifests when Secure Boot mode is enabled by system administrators, creating a scenario where the firmware fails to properly validate the authenticity of code before execution. The flaw fundamentally undermines the trust model that Secure Boot is designed to establish between the hardware platform and the operating system, creating a pathway for malicious actors to bypass critical security controls that are intended to prevent unauthorized code execution.
The technical nature of this vulnerability stems from improper implementation of the UEFI Secure Boot specification, which is governed by the UEFI Forum standards and aligns with the Common Weakness Enumeration CWE-377 weakness category. When Secure Boot is enabled, the system should verify digital signatures of bootloaders and operating system components against trusted certificate authorities before allowing execution. However, in affected Lenovo System x servers, this verification process is insufficient or flawed, allowing unsigned code to be executed during the boot process. This represents a direct violation of the principle of least privilege and integrity checking that forms the foundation of modern firmware security models.
The operational impact of CVE-2017-3775 is particularly severe given that it requires only physical access to the target system, making it exploitable by attackers who have gained local administrative privileges or physical access to server environments. This vulnerability creates a persistent backdoor that can be leveraged for various malicious activities including bootkits, rootkits, and other low-level attacks that operate below the visibility of traditional operating system security controls. The attack surface expands significantly as this weakness can be exploited to compromise the entire system lifecycle from initial boot through runtime operations, potentially allowing attackers to establish persistence mechanisms that survive operating system reinstallation or updates.
Organizations implementing affected Lenovo System x servers face substantial risk exposure when Secure Boot is enabled, as this vulnerability directly contradicts the security assurances that administrators expect from hardware-level protections. The attack vector is particularly concerning because physical access often represents a trusted access path within many enterprise environments, making this vulnerability particularly dangerous in scenarios where server rooms or data centers do not maintain strict physical security controls. Mitigation strategies should include immediate firmware updates from Lenovo to address the Secure Boot implementation flaw, consideration of disabling Secure Boot in environments where physical security cannot be guaranteed, and implementation of additional monitoring controls to detect unauthorized boot modifications.
The vulnerability demonstrates the critical importance of proper firmware security implementation and highlights the challenges associated with hardware-level security controls in enterprise environments. From an ATT&CK framework perspective, this vulnerability maps to techniques involving bootkit development and persistence mechanisms, specifically targeting the boot process and firmware integrity validation. Organizations should also consider implementing hardware security modules, TPM-based attestation, and comprehensive firmware integrity monitoring solutions to provide defense-in-depth against similar vulnerabilities. The incident underscores the necessity for continuous security validation of firmware components and highlights the need for robust supply chain security practices to prevent such implementation flaws from reaching production environments.