CVE-2018-13787 in X11S
Summary
by MITRE
Certain Supermicro X11S, X10, X9, X8SI, K1SP, C9X299, C7, B1, A2, and A1 products have a misconfigured Descriptor Region, allowing OS programs to modify firmware.
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Analysis
by VulDB Data Team • 03/03/2020
This vulnerability affects a range of Supermicro server products including X11S, X10, X9, X8SI, K1SP, C9X299, C7, B1, A2, and A1 models. The issue stems from a misconfigured Descriptor Region within the firmware architecture that creates an unauthorized access path for operating system programs to modify critical firmware components. The Descriptor Region serves as a control mechanism that defines the permissions and access levels for various firmware regions, and when improperly configured, it allows software running at lower privilege levels to gain unauthorized write access to protected firmware areas. This misconfiguration represents a fundamental flaw in the firmware security model that violates basic principles of privilege separation and access control.
The technical flaw manifests as an insufficient access control mechanism within the firmware descriptor table structure. When firmware is properly configured, the Descriptor Region should enforce strict access controls that prevent operating system software from modifying critical firmware components. However, in the affected Supermicro products, this protection has been disabled or improperly configured, allowing user-mode applications to directly manipulate firmware regions that should remain protected from OS-level access. This creates a persistent security weakness that can be exploited by malware or malicious software running with standard user privileges to gain deeper system control and potentially compromise the entire platform security.
The operational impact of this vulnerability is significant as it fundamentally undermines the integrity of the system firmware and creates a persistent backdoor for attackers. An attacker who gains access to the operating system can leverage this weakness to modify firmware components such as the BIOS/UEFI firmware, which contains critical system configuration data and boot code. This capability allows for persistent rootkit installations, firmware-level malware deployment, and complete system compromise that can survive operating system reinstallation or even hardware replacement. The vulnerability affects the core security architecture of these servers and can lead to complete system takeover, data exfiltration, and long-term persistence within enterprise environments.
Mitigation strategies should focus on immediate firmware updates provided by Supermicro to correct the Descriptor Region configuration. Organizations must also implement firmware integrity monitoring solutions that can detect unauthorized modifications to firmware components. The vulnerability aligns with CWE-284 Access Control Issues and can be categorized under ATT&CK technique T1067.001 for persistence through registry modification, though in this case the persistence occurs at the firmware level rather than the operating system level. Additional protective measures include implementing secure boot mechanisms, enabling firmware write protection where available, and conducting regular firmware integrity checks. System administrators should also consider network segmentation and monitoring to detect potential exploitation attempts, as the vulnerability allows for stealthy modifications that may not immediately manifest as system errors.