CVE-2019-9275 in Android
Summary
by MITRE
In the Android kernel in the mnh driver there is a use after free due to improper locking. 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-2019-9275 resides within the Android kernel's mnh driver, representing a critical security flaw that undermines the integrity of the operating system's privilege management mechanisms. This issue manifests as a use-after-free condition that occurs due to inadequate locking mechanisms within the kernel's memory management subsystem. The mnh driver, which typically handles multimedia and network hardware interactions, becomes a vector for potential privilege escalation attacks when proper synchronization controls are absent during memory allocation and deallocation processes. The vulnerability's classification as a use-after-free directly maps to CWE-416, which specifically addresses the use of memory after it has been freed, creating opportunities for attackers to manipulate memory contents and execute arbitrary code.
The technical implementation of this flaw stems from improper locking mechanisms that govern access to shared resources within the kernel space. When multiple threads or processes attempt to access the same memory region without adequate synchronization, the mnh driver fails to prevent concurrent access patterns that lead to memory corruption. This race condition allows an attacker to exploit the timing window where memory is freed but not yet reallocated, enabling the execution of malicious code with elevated privileges. The absence of proper mutex or spinlock implementations during critical sections of code creates a scenario where memory deallocation occurs while other processes might still reference the freed memory locations, leading to unpredictable behavior and potential code execution.
The operational impact of CVE-2019-9275 extends beyond simple privilege escalation, as it represents a fundamental weakness in Android's kernel security model that could enable complete system compromise. Attackers exploiting this vulnerability can execute code with system-level privileges, bypassing traditional security boundaries and gaining access to sensitive system resources, user data, and communication channels. The lack of user interaction requirements for exploitation makes this vulnerability particularly dangerous as it can be triggered automatically through normal device operations, potentially allowing for silent privilege escalation attacks that go undetected by users and security monitoring systems. This characteristic aligns with ATT&CK technique T1068 which describes the exploitation of legitimate credentials and system privileges for malicious purposes.
Mitigation strategies for this vulnerability require immediate kernel updates from device manufacturers and system administrators, as the flaw exists at the core kernel level where traditional application-level protections cannot provide adequate defense. The recommended approach involves implementing proper locking mechanisms throughout the mnh driver codebase, ensuring that all shared memory access operations are properly synchronized using appropriate kernel synchronization primitives such as mutexes, semaphores, or spinlocks. Additionally, comprehensive code reviews should be conducted to identify similar race conditions in other kernel drivers, as this vulnerability pattern suggests broader systemic issues within the kernel's memory management architecture. Device vendors should also implement robust memory sanitization techniques and runtime checks to detect and prevent memory corruption patterns that could lead to similar use-after-free conditions. The fix must address both the immediate locking deficiencies and establish preventive measures against similar vulnerabilities in the kernel's privilege escalation pathways, as outlined in the CWE-416 category's remediation guidelines for preventing memory management errors.