CVE-2017-18125 in Android
Summary
by MITRE
In Android before security patch level 2018-04-05 on Qualcomm Snapdragon Mobile and Snapdragon Wear MDM9206, MDM9607, MDM9650, SD 210/SD 212/SD 205, SD 835, SD 845, SD 850, when secure camera is activated it stores captured data in protected buffers. The TEE application which uses secure camera expects those buffers to contain data captured during the current camera session. It is possible though for HLOS to put aside and reuse one or more of the protected buffers with previously captured data during next camera session. Such data reuse must be prevented as the TEE applications expects to receive valid data captured during the current session only.
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Analysis
by VulDB Data Team • 01/24/2020
This vulnerability exists in Qualcomm Snapdragon mobile platforms and represents a critical security flaw in the Trusted Execution Environment (TEE) architecture. The issue affects Android devices prior to the security patch level 2018-04-05 and impacts specific Qualcomm chipsets including MDM9206, MDM9607, MDM9650, SD 210/SD 212/SD 205, SD 835, SD 845, and SD 850. The vulnerability stems from improper memory management within the secure camera functionality where protected buffers are not properly isolated between camera sessions. According to CWE-362, this represents a race condition vulnerability where the TEE application expects exclusive access to fresh data during each camera session, yet the operating system may reuse buffers containing stale data from previous sessions. The TEE application responsible for secure camera operations relies on the assumption that protected buffers contain data captured during the current session only, creating a fundamental security breach.
The technical implementation flaw occurs when the Hypervisor Level Operating System (HLOS) reuses protected buffers that were previously populated with data from earlier camera sessions. This buffer reuse violates the fundamental security principle that protected memory regions should remain isolated between different operational contexts. The vulnerability manifests because the TEE application does not validate whether the buffers contain fresh data or previously captured information. From an ATT&CK perspective, this represents a privilege escalation vector through the use of insecure data handling within the TEE environment, specifically targeting the camera subsystem. The issue is particularly concerning because it affects the secure camera functionality that is designed to protect sensitive visual data from unauthorized access, yet the vulnerability allows for data leakage through buffer reuse attacks. The flaw essentially creates a situation where malicious actors could potentially access previously captured camera data through the TEE application interface.
The operational impact of this vulnerability is significant as it compromises the integrity of secure camera operations and potentially exposes sensitive visual information to unauthorized access. When a TEE application processes camera data, it expects each buffer to contain fresh data from the current session, but the reuse of buffers with stale data means that the application could process and potentially leak information from previous camera sessions. This creates a data integrity issue where the TEE application may not be able to distinguish between legitimate current session data and previously captured data. The vulnerability affects all camera sessions that occur after the initial session, as the buffer reuse can occur at any point during the device's operational lifecycle. Attackers could exploit this to gain access to previously captured visual data, potentially including sensitive information that was supposed to be protected by the secure camera functionality. The impact extends beyond simple data leakage to potentially enabling more sophisticated attacks that rely on accessing historical camera data within the TEE environment.
Mitigation strategies for this vulnerability primarily involve applying the security patches released by Qualcomm and device manufacturers as part of the Android security updates. The patch addresses the buffer management issue by ensuring that protected buffers are properly cleared or invalidated between camera sessions, preventing the reuse of stale data. Organizations should also implement monitoring solutions to detect anomalous camera access patterns that might indicate buffer reuse attempts. From a defense-in-depth perspective, implementing additional memory isolation techniques and regular security assessments of TEE applications can help prevent similar vulnerabilities. Device manufacturers should ensure that all TEE components properly validate buffer contents before processing data, implementing checks that verify data freshness and prevent the processing of previously stored information. The vulnerability also highlights the importance of proper buffer management in secure environments and the need for comprehensive testing of memory handling within TEE applications to prevent similar race condition scenarios. Security teams should also consider implementing automated tools to monitor for improper buffer reuse patterns in TEE applications and establish protocols for rapid patch deployment to address such vulnerabilities.