CVE-2017-9607 in Trusted Firmware
Summary
by MITRE
The BL1 FWU SMC handling code in ARM Trusted Firmware before 1.4 might allow attackers to write arbitrary data to secure memory, bypass the bl1_plat_mem_check protection mechanism, cause a denial of service, or possibly have unspecified other impact via a crafted AArch32 image, which triggers an integer overflow.
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Analysis
by VulDB Data Team • 06/05/2026
The vulnerability identified as CVE-2017-9607 resides within the BL1 FWU SMC handling code of ARM Trusted Firmware versions prior to 1.4, representing a critical security flaw that undermines the integrity of secure memory operations. This vulnerability manifests through improper handling of AArch32 images that contain crafted payloads designed to exploit integer overflow conditions within the firmware update mechanism. The flaw specifically affects the boot loader stage one component which is responsible for initializing secure execution environments and managing memory protection boundaries. The integer overflow occurs during memory address calculations when processing firmware update requests, creating opportunities for attackers to manipulate memory layout and bypass established security protections.
The technical exploitation of this vulnerability leverages the absence of proper input validation and bounds checking within the BL1 firmware update handling routines. When a malicious AArch32 image is processed, the integer overflow corrupts memory management calculations, allowing unauthorized write operations to occur in secure memory regions that should remain protected from modification. This flaw directly violates the fundamental security principle of memory isolation and enables attackers to circumvent the bl1_plat_mem_check protection mechanism that is specifically designed to validate memory access permissions and prevent unauthorized modifications to secure firmware areas. The vulnerability stems from CWE-190, which addresses integer overflow conditions, and CWE-122, which covers improper restriction of operations within a memory buffer, both of which are critical weaknesses in memory management implementations.
Operationally, this vulnerability presents significant risks to embedded systems and mobile devices that rely on ARM Trusted Firmware for secure boot processes and runtime protection. Attackers can potentially execute arbitrary code within the secure world, leading to complete system compromise and bypass of hardware security features. The impact extends beyond simple privilege escalation to include denial of service conditions where legitimate firmware updates may be prevented from completing successfully, effectively rendering devices inoperable. Additionally, the unspecified other impacts referenced in the vulnerability description suggest potential for more severe consequences including data exfiltration, persistent backdoor installation, or complete compromise of the trusted execution environment. This vulnerability aligns with ATT&CK technique T1068, which covers exploitation of remote services and system vulnerabilities, and T1547, which addresses boot or logon persistence mechanisms that could be leveraged through compromised firmware components.
Mitigation strategies for CVE-2017-9607 require immediate deployment of ARM Trusted Firmware version 1.4 or later, which includes proper bounds checking and integer overflow protection mechanisms. System administrators should implement firmware update policies that ensure all devices receive the latest security patches and validate that the updated firmware versions contain the necessary protections against integer overflow conditions. Additional defensive measures include monitoring for anomalous firmware update activities and implementing runtime integrity checks that can detect unauthorized modifications to secure memory regions. Organizations should also consider employing hardware security modules or trusted platform modules that can provide additional layers of protection against firmware-level attacks, while maintaining comprehensive logging and audit trails to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of secure firmware development practices and proper input validation in trusted execution environments.