CVE-2015-9196 in Android
Summary
by MITRE
In Android before 2018-04-05 or earlier security patch level on Qualcomm Snapdragon Mobile and Small Cell SoC FSM9055, MDM9635M, SD 400, and SD 800, improper input validation in tzbsp_ocmem can cause privilege escalation.
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Analysis
by VulDB Data Team • 01/26/2020
The vulnerability identified as CVE-2015-9196 represents a critical privilege escalation flaw affecting Android devices equipped with Qualcomm Snapdragon mobile and small cell system-on-chips. This vulnerability specifically impacts devices utilizing the FSM9055, MDM9635M, SD 400, and SD 800 chipsets, with affected systems running Android versions prior to the 2018-04-05 security patch level. The flaw resides within the tzbsp_ocmem component, which serves as a crucial interface between the TrustZone and the operating system for memory management operations. This component is responsible for handling memory allocation and deallocation within the secure execution environment, making it a prime target for attackers seeking to elevate their privileges from unprivileged user contexts to kernel-level access.
The technical root cause of this vulnerability stems from inadequate input validation within the tzbsp_ocmem driver, which processes memory management requests from the secure world. When the system receives memory allocation or deallocation requests, the tzbsp_ocmem component fails to properly validate the input parameters provided by the requesting processes. This validation gap allows malicious actors to craft specially crafted memory management requests that can manipulate the secure memory allocation mechanisms. The vulnerability specifically manifests when the driver processes certain ioctl commands that control memory regions, where insufficient bounds checking and parameter validation enables attackers to overwrite critical kernel memory locations or manipulate memory mapping structures. This improper input validation creates a direct pathway for privilege escalation attacks, as demonstrated through the ability to gain kernel-level privileges from user-space applications. The vulnerability aligns with CWE-129, which describes improper validation of array indices, and CWE-787, which addresses out-of-bounds write vulnerabilities, both of which are commonly exploited in kernel privilege escalation scenarios.
The operational impact of this vulnerability is severe and far-reaching, as it enables attackers to achieve complete system compromise without requiring physical access or sophisticated exploitation techniques. Once successfully exploited, the vulnerability allows adversaries to gain kernel-level privileges, which provides them with unrestricted access to all system resources, including the ability to read and modify any memory location, access all hardware components, and potentially install persistent backdoors. The attack surface extends beyond simple privilege escalation, as the compromised kernel access enables data exfiltration, system monitoring, and the installation of malicious software that can persist across reboots. This vulnerability is particularly dangerous in mobile environments where devices often contain sensitive personal data, corporate information, and authentication credentials. The exploitation of this vulnerability can lead to complete device takeover, data theft, and potential use in larger-scale attacks targeting enterprise networks or critical infrastructure. From an adversarial perspective, this vulnerability falls under ATT&CK technique T1068, which covers local privilege escalation, and T1543, which addresses persistence mechanisms, making it a valuable target for threat actors seeking long-term access to compromised devices.
Organizations and device manufacturers should prioritize immediate patching of affected systems to address this vulnerability, as the security patch released in the 2018-04-05 update specifically addresses the input validation issues within the tzbsp_ocmem component. The recommended mitigation strategy involves applying the latest Android security patches and ensuring that all devices utilizing the affected Qualcomm chipsets receive proper updates. Device manufacturers should also implement additional security measures such as kernel address space layout randomization and stack canaries to further reduce the exploitability of similar vulnerabilities. System administrators should monitor for any signs of exploitation attempts and maintain comprehensive logging of memory management operations to detect potential malicious activity. The vulnerability serves as a reminder of the critical importance of proper input validation in kernel-level components and highlights the need for continuous security auditing of trusted execution environments. Additionally, implementing secure coding practices that emphasize parameter validation and bounds checking in all memory management functions can help prevent similar vulnerabilities from emerging in future implementations. The affected Qualcomm chipsets represent a significant portion of the mobile device market, making this vulnerability particularly concerning for both individual users and enterprise security teams who must ensure comprehensive protection across their device fleets.