CVE-2015-9166 in Android
Summary
by MITRE
In Android before 2018-04-05 or earlier security patch level on Qualcomm Snapdragon Automobile, Snapdragon Mobile, and Snapdragon Wear IPQ4019, MDM9206, MDM9607, MDM9650, MSM8909W, SD 210/SD 212/SD 205, SD 400, SD 410/12, SD 425, SD 430, SD 450, SD 615/16/SD 415, SD 617, SD 625, SD 650/52, SD 808, SD 810, SD 820, SD 820A, SD 835, SD 845, and SD 850, DRM provisioning mechanisms used in QSEE applications have a feature to prevent further provisioning. This is done by creating an SFS file called 'finalize_prov_flag.data' at the end of provisioning. When this feature is enabled, provisioning calls check for the existence of the file in order to decide whether to do provisioning or not. Current implementation allows provisioning without sufficient checks.
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Analysis
by VulDB Data Team • 01/26/2020
The vulnerability described in CVE-2015-9166 represents a critical flaw in the Qualcomm Snapdragon chipset family that affects Android devices released before the 2018-04-05 security patch level. This issue specifically targets the Digital Rights Management (DRM) provisioning mechanisms within the Qualcomm Secure Execution Environment (QSEE) applications. The vulnerability stems from insufficient validation checks during the provisioning process, creating a potential pathway for unauthorized modification of DRM configurations. The affected chipsets include a comprehensive range of Qualcomm mobile, automotive, and wearable processors spanning multiple generations from the SD 200 series through the SD 850 series, indicating the widespread nature of this security weakness.
The technical implementation of this vulnerability involves the creation of a file named 'finalize_prov_flag.data' within the Secure File System (SFS) as part of the DRM provisioning workflow. This file serves as a mechanism to prevent further provisioning attempts once the initial setup has been completed. However, the current implementation fails to properly validate the provisioning state before allowing new provisioning operations to proceed. The flaw allows attackers to bypass the intended protection mechanism by simply removing or manipulating the existence check for this file, effectively enabling unauthorized provisioning operations that should be restricted. This represents a classic case of insufficient input validation and access control, where the system relies on a simple file existence check rather than implementing proper authentication and authorization mechanisms. The vulnerability can be classified under CWE-284 Access Control Issues and specifically relates to improper privilege management within the secure execution environment.
The operational impact of this vulnerability extends beyond simple provisioning bypasses to potentially compromise the entire DRM ecosystem on affected devices. Attackers could exploit this weakness to modify or replace DRM content, potentially enabling unauthorized access to protected media content or creating backdoors within the secure execution environment. The implications are particularly severe given that these chipsets are used in automotive systems, mobile devices, and wearable technology where security and privacy are paramount. The vulnerability creates opportunities for attackers to perform privilege escalation attacks within the QSEE, potentially leading to complete compromise of the device's secure boot process and access to sensitive cryptographic keys stored within the secure environment. This aligns with ATT&CK techniques related to privilege escalation and persistence within secure execution environments. The widespread adoption of these chipsets across multiple device categories means that the potential attack surface is extensive, affecting not just consumer devices but also automotive infotainment systems and wearable devices that rely on Qualcomm's secure processing capabilities.
Mitigation strategies for CVE-2015-9166 should prioritize immediate deployment of the relevant Android security patches released by Qualcomm and device manufacturers. Organizations and individuals should ensure that all affected devices receive the 2018-04-05 security update or later versions that address this provisioning bypass vulnerability. Device manufacturers should implement proper validation checks for provisioning operations, ensuring that the existence of the 'finalize_prov_flag.data' file is verified through secure authentication mechanisms rather than simple file existence checks. The implementation should include proper access control lists and cryptographic verification of provisioning state changes to prevent unauthorized modifications. Security monitoring should be enhanced to detect unusual provisioning activities or attempts to manipulate secure files within the SFS. Additionally, device security teams should consider implementing additional layers of verification for DRM operations and regularly audit provisioning processes to ensure that the secure execution environment maintains proper access controls. The vulnerability highlights the importance of robust secure boot and provisioning mechanisms in embedded systems and demonstrates how seemingly simple file-based state management can create significant security risks when not properly implemented with appropriate access controls and authentication checks.