CVE-2018-5840 in Android
Summary
by MITRE
Buffer Copy without Checking Size of Input can occur during the DRM SDE driver initialization sequence in all Android releases from CAF (Android for MSM, Firefox OS for MSM, QRD Android) using the Linux Kernel.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 02/15/2020
The vulnerability identified as CVE-2018-5840 represents a critical buffer overflow condition within the DRM SDE driver initialization sequence of Android systems based on the Linux kernel. This flaw affects all Android releases from the Code Aurora Forum including Android for MSM, Firefox OS for MSM, and QRD Android platforms, making it a widespread issue across multiple device ecosystems. The vulnerability stems from insufficient input validation during the driver initialization process, specifically when handling buffer operations that do not properly verify the size of incoming data before copying it into fixed-size buffers. This type of vulnerability falls under the CWE-121 category of Buffer Copy without Checking Size of Input, which is classified as a fundamental programming error that can lead to arbitrary code execution and system compromise.
The technical implementation of this vulnerability occurs during the DRM SDE driver initialization sequence where the system attempts to copy data from an untrusted source into a predetermined buffer without first validating whether the source data exceeds the buffer's allocated size. This condition creates a scenario where malicious input can overwrite adjacent memory locations, potentially corrupting critical system data structures or injecting executable code. The flaw is particularly dangerous because it occurs during driver initialization, which typically happens early in the boot process when system privileges are highest and the kernel is in a vulnerable state. Attackers exploiting this vulnerability could leverage the buffer overflow to escalate privileges, execute arbitrary code with kernel-level permissions, or cause system crashes that result in denial of service conditions. The ATT&CK framework categorizes this as a privilege escalation technique through buffer overflow exploitation, specifically targeting kernel-mode components that are essential for system security.
The operational impact of CVE-2018-5840 extends beyond simple system instability to encompass full system compromise and potential data exfiltration capabilities. Devices running affected Android versions become vulnerable to attacks that can bypass security mechanisms such as kernel address space layout randomization and other exploit mitigations. The vulnerability affects a broad range of hardware platforms that utilize the SDE (Secure Display Engine) driver, including smartphones, tablets, and other mobile devices that depend on Qualcomm's MSM (Mobile Station Modem) chipsets. The nature of the flaw means that exploitation could occur through various attack vectors including malicious applications, compromised firmware updates, or even physical device access scenarios. Security researchers have noted that the vulnerability's exploitation potential increases significantly when combined with other weaknesses in the Android security model, particularly in systems that do not implement comprehensive exploit mitigations such as stack canaries or control flow integrity checks.
Mitigation strategies for CVE-2018-5840 require immediate attention from device manufacturers and system administrators to prevent exploitation of this critical vulnerability. The primary recommended approach involves applying the patched kernel versions that include proper input validation and buffer size checking mechanisms during the DRM SDE driver initialization process. Organizations should implement comprehensive patch management protocols to ensure all affected devices receive the necessary security updates promptly. Additionally, system administrators should consider implementing runtime protections such as kernel module signing, integrity checks, and monitoring for suspicious buffer operations that could indicate exploitation attempts. The vulnerability highlights the importance of proper input validation in kernel space code and underscores the need for rigorous security testing of device drivers before deployment. Organizations should also review their security policies to ensure that all system components undergo thorough security analysis, particularly those that handle untrusted input data in kernel mode environments. Given the widespread nature of this vulnerability across multiple Android variants, coordinated patching efforts and security advisories from the Android security team are essential for comprehensive protection against potential exploitation attempts.