CVE-2017-0843 in Android
Summary
by MITRE
An elevation of privilege vulnerability in the MediaTek ccci. Product: Android. Versions: Android kernel. Android ID: A-62670819. References: M-ALPS03361488.
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Analysis
by VulDB Data Team • 12/07/2019
The vulnerability identified as CVE-2017-0843 represents a critical elevation of privilege flaw within the Android kernel, specifically affecting MediaTek chipsets through the ccci driver component. This vulnerability stems from improper input validation and insufficient access controls within the communication interface between the application processor and the modem subsystem. The issue manifests when the ccci driver fails to properly validate user-supplied data during device communication processes, creating a pathway for malicious actors to escalate their privileges from standard user level to system level access. The vulnerability was catalogued under Android ID A-62670819 and documented by MediaTek under reference M-ALPS03361488, indicating its origins within the MediaTek chipset ecosystem.
The technical flaw resides in the ccci (Communication and Control Interface) driver implementation which handles communication between the main processor and the modem subsystem in MediaTek-based Android devices. When the driver processes certain ioctl (input/output control) commands, it does not adequately validate the parameters passed to it, allowing for potential buffer overflows or memory corruption scenarios. This validation gap enables attackers to craft malicious input that can manipulate kernel memory structures, ultimately leading to privilege escalation. The vulnerability specifically affects the kernel-level driver that manages the communication channel, making it particularly dangerous as it operates at the most privileged level of the system. This flaw aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which addresses heap-based buffer overflow issues, though the specific implementation in this case involves kernel memory management rather than user-space buffers.
The operational impact of CVE-2017-0843 is severe and far-reaching across MediaTek-powered Android devices, as successful exploitation allows attackers to gain full system privileges without requiring physical access or prior authentication. Once escalated, attackers can execute arbitrary code with kernel-level permissions, enabling them to modify system files, install malicious applications, access encrypted data, and potentially compromise the entire device. The vulnerability affects devices running Android versions that incorporate the affected MediaTek ccci driver, making it particularly concerning given the widespread adoption of MediaTek chipsets in mobile devices. The attack vector typically involves sending specially crafted commands through the ccci interface, which can be initiated through legitimate system services or applications that interact with modem communication. This vulnerability directly maps to ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation," and T1059, covering "Command and Scripting Interpreter," as it allows for command execution at the highest privilege level.
Mitigation strategies for CVE-2017-0843 focus primarily on patching the affected MediaTek drivers and kernel components, with manufacturers releasing security updates to address the validation issues in the ccci interface. Users should ensure their devices receive timely security updates from their manufacturers, particularly those addressing kernel-level vulnerabilities. System administrators and security professionals should monitor for the presence of affected MediaTek chipsets in deployed devices and prioritize patching efforts accordingly. Additionally, implementing runtime protections such as kernel address space layout randomization and stack canaries can provide defense-in-depth measures, though these are secondary to the primary patching approach. The vulnerability also underscores the importance of proper input validation in kernel drivers, emphasizing the need for comprehensive security testing of communication interfaces between system components. Organizations should also consider implementing device monitoring solutions that can detect anomalous communication patterns through the ccci interface, serving as an early warning system for potential exploitation attempts.