CVE-2017-9679 in Android
Summary
by MITRE
In all Qualcomm products with Android releases from CAF using the Linux kernel, if a userspace string is not NULL-terminated, kernel memory contents can leak to system logs.
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Analysis
by VulDB Data Team • 11/09/2019
The vulnerability identified as CVE-2017-9679 represents a critical information disclosure flaw within Qualcomm's Android implementations that leverages kernel memory leakage through improper string handling. This vulnerability affects all Qualcomm products utilizing Android releases from the Code Aurora Forum that operate on the Linux kernel architecture. The flaw manifests when userspace applications pass strings to kernel space without ensuring proper NULL termination, creating a condition where kernel memory contents become accessible to system logging mechanisms. This issue stems from inadequate input validation and memory management practices within the kernel's string processing routines, particularly in how kernel space handles potentially malformed string data from userspace applications.
The technical exploitation of this vulnerability occurs through the kernel's logging subsystem where improperly terminated strings are processed and subsequently logged to system logs. When a userspace application provides a string that lacks proper NULL termination, the kernel's string handling functions may read beyond the intended string boundaries, inadvertently including adjacent kernel memory contents in the log output. This memory leakage can expose sensitive information such as kernel stack contents, memory addresses, cryptographic keys, or other confidential data that resides in the kernel's memory space. The vulnerability is classified under CWE-126 as "Buffer Over-read" and specifically relates to improper handling of buffer boundaries in kernel space operations, making it a direct threat to system confidentiality and integrity.
The operational impact of CVE-2017-9679 extends beyond simple information disclosure, as the leaked kernel memory contents can provide attackers with valuable insights into the system's internal state and memory layout. This information can be leveraged to facilitate more sophisticated attacks including kernel exploitation, privilege escalation, or targeted attacks against specific memory regions. The vulnerability affects a broad range of Qualcomm-based devices including smartphones, tablets, and other mobile platforms that utilize the Linux kernel for their Android implementations. According to ATT&CK framework category T1059, this vulnerability enables adversaries to gather system information through command and scripting interfaces, while T1068 relates to the potential for privilege escalation once attackers obtain kernel memory information. The exposure of kernel memory contents creates a pathway for attackers to understand the system's memory organization, which can aid in bypassing security mitigations such as stack canaries, address space layout randomization, and other exploit prevention mechanisms.
Mitigation strategies for this vulnerability require immediate implementation of proper string validation and boundary checking within kernel space code. System administrators should ensure that all kernel modules and drivers implement robust input validation to prevent improper string handling and memory over-read conditions. The recommended approach involves enforcing NULL termination of strings before processing them in kernel space, implementing proper buffer size checking, and utilizing kernel memory protection mechanisms such as kernel page table isolation and memory sanitization routines. Additionally, regular security updates and patches from Qualcomm should be applied immediately to address this vulnerability. Organizations should also implement monitoring of system logs for unusual memory content patterns that might indicate exploitation attempts, while maintaining comprehensive system integrity verification procedures. The vulnerability highlights the importance of adhering to secure coding practices in kernel space development and demonstrates how seemingly minor input validation flaws can lead to significant security implications in embedded systems and mobile platforms.