CVE-2019-6260 in ast2400
Summary
by MITRE
The ASPEED ast2400 and ast2500 Baseband Management Controller (BMC) hardware and firmware implement Advanced High-performance Bus (AHB) bridges, which allow arbitrary read and write access to the BMC's physical address space from the host (or from the network in unusual cases where the BMC console uart is attached to a serial concentrator). This CVE applies to the specific cases of iLPC2AHB bridge Pt I, iLPC2AHB bridge Pt II, PCIe VGA P2A bridge, DMA from/to arbitrary BMC memory via X-DMA, UART-based SoC Debug interface, LPC2AHB bridge, PCIe BMC P2A bridge, and Watchdog setup.
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Analysis
by VulDB Data Team • 05/04/2020
The vulnerability described in CVE-2019-6260 represents a critical security flaw in ASPEED AST2400 and AST2500 Baseband Management Controllers that fundamentally compromises the isolation between the host system and the BMC's memory space. This vulnerability stems from the implementation of Advanced High-performance Bus (AHB) bridges within the BMC hardware and firmware, creating pathways that allow unauthorized access to the BMC's physical address space. The affected bridges include iLPC2AHB bridge Pt I and II, PCIe VGA P2A bridge, X-DMA bridges for memory transfers, UART-based SoC Debug interfaces, LPC2AHB bridge, PCIe BMC P2A bridge, and Watchdog setup components. These bridges essentially create backdoors in the security architecture that should normally maintain strict separation between the host system and the isolated BMC environment.
The technical flaw manifests through the improper implementation of memory access controls within the BMC's hardware bridge components, enabling attackers with access to the host system or network to perform arbitrary read and write operations against the BMC's physical memory address space. This vulnerability is particularly dangerous because it operates at a hardware level, bypassing traditional software-based security measures and operating system protections. The attack surface expands significantly when considering that network-based access can be achieved through unusual configurations where the BMC console uart is connected to a serial concentrator, potentially allowing remote exploitation from outside the local network. This architectural weakness directly violates the fundamental principle of hardware isolation that BMCs are designed to provide, creating a persistent threat vector that can be exploited by both local and remote attackers.
The operational impact of this vulnerability is severe and far-reaching, as it provides attackers with complete control over the BMC's memory space and potentially the entire system it manages. An attacker who successfully exploits this vulnerability can access sensitive system information, modify critical firmware components, manipulate system configuration parameters, and potentially establish persistent backdoors within the BMC environment. The vulnerability affects the core management capabilities of the system, potentially allowing attackers to disable security features, modify system behavior, or gain elevated privileges that would normally be restricted to authorized administrators. The impact extends beyond simple data theft to include system compromise and potential denial of service conditions that could render the managed system inoperable.
Mitigation strategies for CVE-2019-6260 require both immediate hardware-level and software-based approaches to address the fundamental architectural flaw. Organizations should implement network segmentation and access control measures to limit exposure of BMC interfaces, particularly the UART-based debug interfaces and serial concentrator connections that may provide remote access paths. Firmware updates from ASPEED are essential to address the specific bridge implementations that create the vulnerability, though these updates may not be available for all affected systems. The implementation of secure boot mechanisms and memory protection features can help limit the damage if exploitation occurs, while regular monitoring of BMC network traffic and system logs can help detect unauthorized access attempts. According to CWE standards, this vulnerability maps to CWE-284 Access Control Issues, specifically related to insufficient access control mechanisms in hardware bridges, and aligns with ATT&CK techniques involving privilege escalation and persistence through system firmware manipulation. The vulnerability underscores the importance of secure hardware design principles and the critical need for proper isolation mechanisms in management controller implementations.