CVE-2017-7932 in i.MX 28
Summary
by MITRE
An improper certificate validation issue was discovered in NXP i.MX 28 i.MX 50, i.MX 53, i.MX 7Solo i.MX 7Dual Vybrid VF3xx, Vybrid VF5xx, Vybrid VF6xx, i.MX 6ULL, i.MX 6UltraLite, i.MX 6SoloLite, i.MX 6Solo, i.MX 6DualLite, i.MX 6SoloX, i.MX 6Dual, i.MX 6Quad, i.MX 6DualPlus, and i.MX 6QuadPlus. When the device is configured in security enabled configuration, under certain conditions it is possible to bypass the signature verification by using a specially crafted certificate leading to the execution of an unsigned image.
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Analysis
by VulDB Data Team • 01/07/2021
The vulnerability identified as CVE-2017-7932 represents a critical weakness in the cryptographic validation mechanisms of NXP's i.MX series of application processors, affecting a broad range of devices including the i.MX 28, 50, 53, 7Solo, Vybrid VF3xx, VF5xx, VF6xx, 6ULL, 6UltraLite, 6SoloLite, 6Solo, 6DualLite, 6SoloX, 6Dual, 6Quad, 6DualPlus, and 6QuadPlus models. This issue stems from improper certificate validation procedures that are fundamental to the secure boot process of these embedded systems. The vulnerability specifically targets devices configured in security enabled mode, where cryptographic signatures are supposed to verify the authenticity and integrity of firmware images before execution. The flaw allows attackers to bypass signature verification through the use of specially crafted certificates, effectively undermining the entire security architecture designed to prevent unauthorized code execution.
The technical implementation of this vulnerability resides in the certificate validation logic within the secure boot chain of these processors. When a device operates in security enabled configuration, it expects certificates to contain valid signatures that can be verified against trusted root certificates. However, the flawed validation process permits certain malformed or crafted certificates to pass verification checks, allowing unsigned images to be executed. This weakness directly relates to CWE-330, which addresses the use of insufficiently random values in cryptographic operations, and can be categorized under CWE-295, which covers improper certificate validation. The vulnerability exploits the trust model inherent in the secure boot process, where the system assumes that valid certificates can be trusted to authenticate code integrity, but fails to properly validate the certificate's signature chain or structure.
The operational impact of this vulnerability extends across numerous embedded systems and IoT devices that rely on NXP's i.MX processors for secure operations. Devices utilizing these processors include industrial control systems, automotive electronics, network appliances, and various security appliances where firmware integrity is paramount. An attacker exploiting this vulnerability could potentially install malicious firmware, execute unauthorized code, or compromise the entire device's security posture. The implications are particularly severe in industrial environments where these processors are used for critical control systems, as they could enable attackers to gain unauthorized access to operational technology infrastructure. This vulnerability essentially creates a backdoor that bypasses the fundamental security mechanisms designed to protect against firmware tampering, making it a significant concern for device manufacturers and security administrators who rely on secure boot processes for device integrity.
Mitigation strategies for CVE-2017-7932 should focus on both immediate remediation and long-term architectural improvements. Device manufacturers should implement firmware updates that correct the certificate validation logic, ensuring that all certificates undergo proper signature verification before code execution is permitted. The fix should enforce stricter certificate validation procedures that properly check certificate structures, signature algorithms, and chain of trust relationships. Additionally, system administrators should consider implementing runtime monitoring to detect anomalous certificate usage patterns or unauthorized code execution attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and execution of malicious code through compromised firmware, specifically related to T1072 and T1059. Organizations should also review their supply chain security practices to ensure that only authenticated and verified firmware images are deployed to affected devices, and implement continuous security monitoring to detect potential exploitation attempts. The vulnerability underscores the importance of proper cryptographic implementation in embedded systems and highlights the need for comprehensive security testing of secure boot mechanisms before deployment in production environments.