CVE-2017-18141 in Snapdragon Automobile
Summary
by MITRE
When a 3rd party TEE has been loaded it is possible for the non-secure world to create a secure monitor call which will give it access to privileged functions meant to only be accessible from the TEE in Snapdragon Automobile, Snapdragon Mobile and Snapdragon Wear in versions IPQ8074, MDM9206, MDM9607, MDM9635M, MDM9650, MDM9655, MSM8996AU, SD 210/SD 212/SD 205, SD 410/12, SD 425, SD 427, SD 430, SD 435, SD 439 / SD 429, SD 450, SD 625, SD 632, SD 636, SD 650/52, SD 810, SD 820, SD 820A, SD 835, SDA660, SDM439, SDM630, SDM660, SDX24, Snapdragon_High_Med_2016.
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Analysis
by VulDB Data Team • 05/04/2020
This vulnerability represents a critical flaw in the secure execution environment of Qualcomm Snapdragon processors where the boundary between secure and non-secure worlds becomes compromised. The issue manifests when a third-party trusted execution environment has been loaded onto the system, creating an unexpected pathway for privilege escalation. The vulnerability specifically affects the secure monitor call mechanism that should normally only be accessible from within the trusted execution environment itself, but can now be invoked from the non-secure world through crafted malicious code execution.
The technical implementation of this flaw involves a breakdown in the ARM TrustZone security architecture where the secure monitor call interface fails to properly validate the calling context. This allows malicious actors in the non-secure world to forge secure monitor calls that would normally only be permitted from within the TEE, effectively bypassing the fundamental security boundaries designed to isolate sensitive operations. The vulnerability stems from inadequate validation of the execution context when handling secure monitor calls, creating a privilege escalation vector that can be exploited by attackers with access to the non-secure execution environment.
The operational impact of this vulnerability is severe across all affected Snapdragon platforms, potentially enabling attackers to gain unauthorized access to privileged functions that should remain isolated within the trusted execution environment. This could allow for extraction of sensitive cryptographic keys, manipulation of secure storage, or execution of arbitrary code with elevated privileges that would normally be restricted to the TEE. The vulnerability affects a wide range of devices including automotive systems, mobile phones, and wearable devices, making it particularly dangerous as it could compromise security across multiple device categories. Attackers could leverage this vulnerability to perform persistent exploitation that would be difficult to detect and remediate.
The security implications extend beyond simple privilege escalation into more complex attack vectors that align with several ATT&CK framework techniques including privilege escalation, defense evasion, and credential access. This vulnerability directly maps to CWE-284 which describes improper access control in software systems, and represents a failure in the mandatory access control mechanisms that should protect the secure world from unauthorized access. The affected hardware platforms span multiple generations of Qualcomm processors, indicating this is not a localized issue but rather a systemic flaw in the secure world implementation. Organizations should implement immediate mitigations including firmware updates from device manufacturers, disabling third-party TEE components where possible, and monitoring for suspicious secure monitor call activity. The vulnerability also highlights the importance of proper secure world boundary enforcement and the need for comprehensive testing of inter-world communication mechanisms in trusted execution environments.