CVE-2017-9724 in Android
Summary
by MITRE
In all Qualcomm products with Android releases from CAF using the Linux kernel, user-level permissions can be used to gain access to kernel memory, specifically the ION cache maintenance code is writing to a user supplied address.
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Analysis
by VulDB Data Team • 01/14/2021
The vulnerability identified as CVE-2017-9724 represents a critical privilege escalation flaw within Qualcomm-based Android devices that utilize the Linux kernel. This issue stems from improper input validation within the ION cache maintenance code, which is a memory management component designed to handle buffer allocations and cache operations in embedded systems. The vulnerability specifically affects devices running Android versions that incorporate Qualcomm's Android Common HAL (CAF) implementations, creating a widespread impact across numerous mobile devices and embedded systems that rely on Qualcomm's hardware platforms. The flaw resides in the kernel-level code responsible for managing memory cache operations, where user-space applications can manipulate memory addresses through the ION subsystem.
The technical implementation of this vulnerability involves a direct write operation to user-supplied memory addresses within kernel space, bypassing normal memory protection mechanisms. When the ION cache maintenance code processes user-provided parameters, it fails to validate the memory addresses before performing write operations, allowing malicious applications to specify arbitrary kernel memory locations. This creates a privilege escalation vector where applications with standard user permissions can directly manipulate kernel memory structures, potentially leading to complete system compromise. The vulnerability manifests through improper bounds checking and address validation within the kernel's memory management subsystem, which is classified under CWE-787 as "Out-of-bounds Write" and CWE-122 as "Heap-based Buffer Overflow." The flaw enables attackers to write to kernel memory locations that should remain protected, fundamentally undermining the security model of the operating system.
The operational impact of CVE-2017-9724 extends beyond simple privilege escalation, as it provides attackers with the capability to manipulate critical kernel data structures and potentially execute arbitrary code with kernel-level privileges. This vulnerability allows malicious actors to gain access to sensitive kernel memory regions, potentially enabling them to modify system call tables, alter security policies, or extract confidential information from kernel memory. The implications are particularly severe in mobile environments where users frequently install third-party applications, as the vulnerability can be exploited through seemingly benign applications that request standard permissions. Attackers can leverage this flaw to establish persistent backdoors, modify system integrity checks, or disable security mechanisms, creating a persistent threat that can survive device reboots and software updates. This vulnerability directly aligns with ATT&CK technique T1068 as "Local Privilege Escalation" and T1059 as "Command and Scripting Interpreter" when used to execute malicious payloads within kernel space.
Mitigation strategies for CVE-2017-9724 require immediate patching of affected Qualcomm platforms and kernel versions, as the vulnerability cannot be effectively addressed through configuration changes alone. Device manufacturers must implement comprehensive security updates that include proper input validation within the ION cache maintenance code and address the root cause of the memory address handling. System administrators should monitor for patches from Qualcomm and Android vendors, particularly focusing on kernel updates that address memory management vulnerabilities in the ION subsystem. The vulnerability highlights the importance of kernel memory protection mechanisms and proper input validation in embedded systems, emphasizing the need for robust security testing of kernel components. Organizations should implement continuous monitoring for similar vulnerabilities in memory management subsystems and consider implementing additional security controls such as kernel address space layout randomization and stack canaries to mitigate the impact of similar future vulnerabilities. The remediation process should include thorough testing of patches to ensure that security updates do not introduce regressions in device functionality while effectively closing the privilege escalation pathway.