CVE-2018-9513 in Android
Summary
by MITRE
In copy_process of fork.c, there is possible memory corruption due to a double free. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Product: Android Versions: Android kernel Android ID: A-111081202 References: N/A
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Analysis
by VulDB Data Team • 03/29/2020
The vulnerability identified as CVE-2018-9513 represents a critical memory corruption issue within the Android kernel's process forking mechanism. This flaw exists in the copy_process function located within the fork.c source file, where a double free condition can occur during the kernel's process duplication operations. The vulnerability specifically targets the kernel's memory management subsystem and exploits a fundamental flaw in how the kernel handles process creation and memory allocation during fork operations. The double free condition arises when the kernel attempts to release the same memory block twice, potentially leading to memory corruption that can be leveraged for privilege escalation.
The technical nature of this vulnerability stems from improper memory management within the kernel's process forking implementation. When a process attempts to create a child process through the fork system call, the kernel's copy_process function handles the duplication of process metadata and memory structures. The double free condition occurs when the kernel's memory allocator encounters a scenario where a memory block is freed twice before being reallocated, creating a state where the memory management structures become corrupted. This memory corruption can be exploited by malicious processes to manipulate kernel memory layouts and potentially gain elevated privileges. The vulnerability operates at the kernel level, making it particularly dangerous as it can be exploited without requiring any special execution privileges or user interaction.
The operational impact of CVE-2018-9513 extends beyond simple memory corruption, presenting a direct path to local privilege escalation within Android devices. Since the vulnerability is triggered during normal process creation operations, any application or process running on the device can potentially exploit this flaw to gain root-level access to the kernel. This represents a significant security risk as it allows attackers to bypass normal access controls and execute arbitrary code with the highest privileges available to the kernel. The lack of user interaction requirements makes this vulnerability particularly concerning for mobile environments where users may not be aware of the exploitation occurring in the background. The vulnerability affects Android kernel versions, making it potentially widespread across numerous Android devices and versions that rely on the affected kernel implementation.
This vulnerability maps to CWE-415, which describes improper handling of double free conditions in memory management. The flaw demonstrates a classic example of memory safety issues that can be exploited for privilege escalation in kernel environments. From an attack perspective, this vulnerability aligns with ATT&CK technique T1068, which involves exploiting vulnerabilities to gain elevated privileges. The exploitation process typically involves creating a scenario where the kernel's memory allocator encounters the double free condition, potentially allowing attackers to manipulate memory structures and execute code with kernel-level privileges. The vulnerability's impact is further amplified by its location within the core process management functionality, making it a fundamental weakness in the Android security model.
Mitigation strategies for CVE-2018-9513 primarily involve applying the relevant kernel security patches provided by Android. Device manufacturers and users should ensure that all Android devices receive the appropriate kernel updates that address this memory management flaw. The fix typically involves implementing proper memory management checks within the copy_process function to prevent the double free condition from occurring. Additionally, system administrators should monitor for any signs of exploitation attempts and consider implementing additional security monitoring mechanisms. The vulnerability also highlights the importance of kernel memory safety testing and the need for robust memory management validation in security-critical systems. Regular security audits of kernel code should be conducted to identify and address similar memory corruption vulnerabilities before they can be exploited in the wild.