CVE-2019-9441 in Android
Summary
by MITRE
In the Android kernel in the mnh driver there is a possible out of bounds write due to improper input validation. This could lead to escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 12/13/2023
The vulnerability identified as CVE-2019-9441 resides within the Android kernel's mnh driver, representing a critical security flaw that could enable privilege escalation attacks. This issue manifests as a potential out of bounds write condition that stems from inadequate input validation mechanisms within the kernel module. The mnh driver, which typically handles multimedia and networking functions, contains a flaw that allows malicious code to write data beyond the allocated memory boundaries of the affected buffer. Such vulnerabilities are particularly dangerous in kernel space contexts where the attacker can leverage the flaw to gain elevated privileges and execute code with system-level permissions. The vulnerability's classification as a privilege escalation issue indicates that exploitation would allow an attacker to move from a lower-privileged user context to a system-level execution environment, fundamentally compromising the device's security posture.
The technical nature of this flaw aligns with CWE-787, which specifically addresses out of bounds write vulnerabilities in software systems. The improper input validation in the mnh driver's kernel module creates an environment where attacker-controlled data can be processed without adequate boundary checks, leading to memory corruption that could be exploited for arbitrary code execution. This type of vulnerability typically occurs when the driver fails to validate the size or content of incoming data structures before processing them, allowing an attacker to craft inputs that exceed the intended buffer boundaries. The exploitation requires system execution privileges as a precondition, meaning that while the initial access might come from a regular user context, the vulnerability's successful exploitation necessitates the ability to execute code at the system level. This requirement suggests that the vulnerability may be chained with other exploits or that the target system has already been compromised through different attack vectors.
The operational impact of CVE-2019-9441 extends beyond simple data corruption, as it provides a pathway for full system compromise through privilege escalation. Attackers could leverage this vulnerability to gain root access to affected Android devices, potentially leading to complete device takeover, data exfiltration, and persistent backdoor installation. The fact that user interaction is not required for exploitation makes this vulnerability particularly concerning as it can be triggered automatically through various attack scenarios including malicious applications or network-based attacks. The vulnerability affects Android devices that utilize the affected kernel version and mnh driver implementation, potentially impacting a wide range of mobile devices and embedded systems. Organizations and users should consider this vulnerability as a critical threat requiring immediate attention, as it represents a fundamental weakness in the kernel's memory management and input validation processes that could be exploited by sophisticated attackers.
Mitigation strategies for CVE-2019-9441 should focus on both immediate patching and defensive measures. The primary solution involves applying the relevant security patches provided by Android vendors and device manufacturers to update the kernel and mnh driver components. Additionally, implementing kernel memory protection mechanisms such as stack canaries, address space layout randomization, and kernel address space layout randomization can help reduce the effectiveness of exploitation attempts. System administrators should also consider monitoring for unusual kernel-level activities and implementing application whitelisting to prevent unauthorized code execution. From a broader security perspective, organizations should conduct comprehensive vulnerability assessments to identify other potential kernel-level vulnerabilities and implement robust input validation practices across all system components. The ATT&CK framework's privilege escalation techniques would be relevant for understanding how this vulnerability could be leveraged, particularly in the context of kernel exploits and system-level attack vectors. Regular security updates and kernel hardening practices should be maintained to prevent similar vulnerabilities from being exploited in the future, as this type of flaw demonstrates the critical importance of robust input validation in kernel space operations.