CVE-2018-1992 in Power 9 OP910
Summary
by MITRE
The IBM Power 9 OP910, OP920, and FW910 boot firmware's bootloader is responsible for loading and validating the initial boot firmware image that drives the rest of the system's hardware initialization. The bootloader firmware contains a buffer overflow vulnerability such that, if an attacker were able to replace the initial boot firmware image with a very carefully crafted and sufficiently large, malicious replacement, it could cause the bootloader, during the load of that image, to overwrite its own instruction memory and circumvent secure boot protections, install trojans, etc. IBM X-Force ID: 154345.
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Analysis
by VulDB Data Team • 08/03/2023
The vulnerability identified as CVE-2018-1992 resides within the bootloader firmware of IBM Power 9 systems including models OP910, OP920, and FW910. This represents a critical security flaw that directly impacts the system's boot process and hardware initialization sequence. The bootloader serves as the primary gatekeeper for the firmware loading process, making it a prime target for attackers seeking to compromise system integrity from the earliest stages of operation. The vulnerability stems from inadequate input validation within the bootloader's memory management functions, creating a condition where maliciously crafted firmware images can trigger buffer overflow conditions.
This buffer overflow vulnerability operates through a classic memory corruption attack vector where an attacker can manipulate the bootloader's behavior by replacing the legitimate boot firmware image with a specially crafted malicious payload. The attack requires the attacker to have physical access to the system or the ability to influence the boot process through supply chain compromise or other means of firmware manipulation. When the vulnerable bootloader attempts to load the oversized malicious firmware image, it fails to properly bounds-check the input data, leading to memory corruption that overwrites the bootloader's own instruction memory space. This allows for complete bypass of the secure boot protections that are designed to prevent unauthorized firmware modifications.
The operational impact of this vulnerability extends far beyond simple system compromise, as it enables attackers to completely circumvent the hardware-level security controls that protect against malicious firmware installation. The ability to overwrite instruction memory means that attackers can effectively rewrite the bootloader's own code execution flow, allowing them to install persistent trojan malware that survives system reboots and operates below the level of normal operating system security controls. This vulnerability represents a fundamental breach in the system's trust model, as it allows attackers to gain control before the operating system has any opportunity to enforce security policies. The implications align with CWE-121, which describes heap-based buffer overflow conditions, and the attack pattern corresponds to techniques described in the ATT&CK framework under T1068 for exploit for privilege escalation.
Mitigation strategies for this vulnerability require immediate attention from system administrators and security teams responsible for IBM Power 9 environments. The primary recommendation involves applying the official firmware updates provided by IBM to patch the buffer overflow condition in the bootloader firmware. Organizations should also implement robust firmware integrity monitoring solutions that can detect unauthorized modifications to the boot process. Physical security measures become paramount, as the vulnerability requires either direct system access or supply chain compromise to exploit effectively. Network segmentation and access controls should be strengthened to limit potential attack vectors, while regular firmware integrity checks should be implemented as part of the overall security monitoring program. The vulnerability demonstrates the critical importance of securing firmware supply chains and implementing defense-in-depth strategies that protect system integrity at all levels of the computing stack.