CVE-2018-9399 in Android
Summary
by MITRE • 12/05/2024
In /proc/driver/wmt_dbg driver, there are several possible out of bounds writes. These could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 12/19/2024
The vulnerability identified as CVE-2018-9399 resides within the /proc/driver/wmt_dbg driver component, which represents a critical security flaw in embedded systems and mobile device kernels. This driver interface exposes kernel-level functionality through the proc filesystem, making it accessible to user-space processes while maintaining system-level privileges. The vulnerability manifests as multiple out-of-bounds write conditions that occur when processing input data from user-space applications interacting with the driver through the /proc interface. These buffer overflows represent a fundamental breakdown in input validation and memory management practices within the kernel driver code.
The technical nature of this flaw stems from inadequate bounds checking during data processing within the wmt_dbg driver implementation. When user-space applications submit malformed or oversized data structures to the driver through the /proc interface, the driver fails to properly validate input lengths before writing to allocated memory buffers. This results in memory corruption that can overwrite adjacent kernel memory locations, potentially including critical data structures, function pointers, or privilege control mechanisms. The vulnerability requires system execution privileges for exploitation, indicating that attackers must already have access to the system to initiate the attack, though the end result provides a path to escalate privileges to system level. This aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-787, which covers out-of-bounds write vulnerabilities in heap-based memory structures.
The operational impact of CVE-2018-9399 represents a significant threat to system integrity and security, as local privilege escalation vulnerabilities can be exploited by malicious actors to gain root-level access to affected systems. Once escalated to system privileges, attackers can manipulate core system functions, modify critical files, install persistent backdoors, or extract sensitive information from the device. The lack of user interaction requirements for exploitation makes this vulnerability particularly dangerous as it can be triggered automatically through malicious applications or scripts without requiring user deception or social engineering tactics. This characteristic places the vulnerability within ATT&CK framework category TA0004 (Privilege Escalation) and specifically maps to techniques such as T1068 (Local Privilege Escalation) and T1548.001 (Abuse Elevation Control Mechanism). The vulnerability affects systems running kernel versions that include the problematic wmt_dbg driver, typically found in embedded devices, smartphones, and IoT systems that utilize MediaTek chipsets.
Mitigation strategies for CVE-2018-9399 should focus on both immediate patching and defensive measures to reduce attack surface. The primary solution involves applying kernel updates from device manufacturers that include fixed versions of the wmt_dbg driver with proper bounds checking and input validation mechanisms. System administrators should implement strict access controls for /proc filesystem entries and consider disabling unnecessary driver interfaces when not required for system operation. Additionally, monitoring for unusual patterns of access to the /proc/driver/wmt_dbg interface can help detect potential exploitation attempts. Organizations should also consider implementing kernel hardening techniques such as stack canaries, address space layout randomization, and kernel address space protection mechanisms. The vulnerability highlights the importance of secure coding practices in kernel-space development and underscores the need for comprehensive input validation and bounds checking throughout all driver interfaces to prevent similar issues from occurring in future implementations.