CVE-2018-9388 in Android
Summary
by MITRE • 12/06/2024
In store_upgrade and store_cmd of drivers/input/touchscreen/stm/ftm4_pdc.c, there are out of bound writes due to missing bounds checks or integer underflows. These could lead to escalation of privilege.
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Analysis
by VulDB Data Team • 12/19/2024
The vulnerability identified as CVE-2018-9388 resides within the touchscreen driver component of the Linux kernel, specifically in the stm/ftm4_pdc.c file where the store_upgrade and store_cmd functions handle input commands from userspace. This flaw represents a critical security issue that can potentially allow attackers to escalate privileges by exploiting out-of-bounds write conditions. The vulnerability manifests when the driver fails to perform proper bounds checking on data received from user applications, creating opportunities for malicious input to overwrite memory locations beyond the intended buffer boundaries.
The technical implementation of this vulnerability stems from the absence of adequate input validation mechanisms within the touch controller driver. When processing commands through the sysfs interface, the store_upgrade and store_cmd functions do not properly validate the size or content of incoming data before writing to kernel memory regions. This missing bounds checking allows for integer underflows and overflows that can result in memory corruption, enabling attackers to write data beyond the allocated buffer space. The flaw aligns with CWE-129, which describes improper validation of array index or count values, and CWE-190, which addresses integer overflow or wraparound conditions that can lead to memory corruption.
From an operational perspective, this vulnerability presents a significant risk to embedded systems and devices that rely on touchscreen functionality, particularly those running Linux-based operating systems. Attackers could exploit this weakness by crafting malicious input commands that trigger the out-of-bounds write conditions, potentially leading to privilege escalation from user mode to kernel mode. The impact extends beyond simple memory corruption, as successful exploitation could allow attackers to execute arbitrary code with kernel-level privileges, effectively compromising the entire system. This vulnerability affects devices such as industrial control systems, automotive infotainment systems, and IoT devices that utilize the stm touchscreen driver.
The exploitation of this vulnerability requires an attacker to have access to the device's input subsystem and the ability to write to the relevant sysfs interfaces. According to ATT&CK framework category T1068, this represents a privilege escalation technique through kernel vulnerabilities. The attack vector typically involves sending specially crafted commands to the touchscreen driver through the sysfs interface, where the lack of proper input validation allows for memory corruption. Organizations should consider this vulnerability as part of their broader kernel security posture assessment, particularly in environments where physical access to touchscreen devices is possible.
Mitigation strategies for CVE-2018-9388 should include immediate patching of affected kernel versions, implementation of proper input validation mechanisms within the driver code, and deployment of kernel security modules such as kernel address space layout randomization. System administrators should also consider disabling unnecessary sysfs interfaces when possible and implementing proper access controls to limit exposure. The fix requires adding comprehensive bounds checking to prevent integer underflows and ensuring that all input data is validated before being processed by the driver functions. Additionally, regular security audits of kernel drivers should be conducted to identify similar vulnerabilities that may exist in other device drivers within the system.