CVE-2016-6675 in Android
Summary
by MITRE
Off-by-one error in CORE/HDD/src/wlan_hdd_hostapd.c in the Qualcomm Wi-Fi driver in Android before 2016-10-05 on Nexus 5X and Android One devices allows attackers to gain privileges or cause a denial of service (buffer overflow) via a crafted application that makes a linkspeed ioctl call, aka Android internal bug 30873776 and Qualcomm internal bug CR 1000861.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability described in CVE-2016-6675 represents a critical off-by-one error within the Qualcomm Wi-Fi driver implementation on Android devices, specifically affecting Nexus 5X and Android One models. This flaw exists in the wlan_hdd_hostapd.c source file within the CORE/HDD/src directory of the Qualcomm Android Wi-Fi driver stack, making it a fundamental issue in the wireless networking subsystem that handles Wi-Fi access point operations and hostapd integration. The vulnerability stems from improper bounds checking during ioctl command processing, particularly when handling linkspeed requests, which creates a condition where one extra byte can be written beyond allocated buffer boundaries. This type of error falls under CWE-121, which specifically addresses buffer overflow conditions where insufficient bounds checking allows memory corruption through array indexing or pointer arithmetic errors.
The technical exploitation of this vulnerability occurs when a malicious application invokes a linkspeed ioctl call that triggers the flawed buffer handling logic. When the driver processes this ioctl command, the off-by-one error allows an attacker to write data beyond the intended buffer limits, potentially overwriting adjacent memory locations with controlled data. This memory corruption can manifest in two primary ways: either by allowing privilege escalation to kernel-level access or by causing a denial of service through system crashes and reboot cycles. The flaw is particularly dangerous because it operates at the kernel level within the Wi-Fi driver, meaning that a compromised user-space application can potentially gain root-level privileges and execute arbitrary code with full system access. The vulnerability impacts devices running Android versions prior to 2016-10-05, representing a significant window of affected devices that were widely distributed and in active use.
The operational impact of CVE-2016-6675 extends beyond simple system instability to represent a serious security risk for affected Android devices. Attackers could leverage this vulnerability to execute remote code execution attacks, potentially compromising user data, accessing sensitive communications, or establishing persistent backdoors on the affected devices. The vulnerability affects the core wireless networking functionality and could be exploited to disrupt network connectivity, steal credentials, or perform man-in-the-middle attacks on Wi-Fi communications. From an attacker's perspective, this represents a low-effort, high-impact exploit opportunity since it only requires a legitimate application to be installed and executed, with no additional privileges or user interaction required. The vulnerability also has implications for enterprise security environments where these devices might be used for corporate communications, as the privilege escalation capability could enable attackers to access sensitive business data or establish persistent access to corporate networks through compromised devices.
Mitigation strategies for this vulnerability must address both the immediate security risk and the underlying architectural issues that allowed the flaw to persist. Device manufacturers should implement immediate security patches that correct the buffer bounds checking in the wlan_hdd_hostapd.c file, ensuring that all ioctl calls properly validate input parameters and enforce proper buffer boundaries. The fix should include proper bounds checking mechanisms that prevent any writes beyond allocated memory regions, implementing defensive programming practices that align with secure coding standards. Organizations should also deploy mobile device management solutions that can monitor for suspicious application behavior and prevent installation of potentially malicious applications that could exploit this vulnerability. Additionally, network administrators should implement network segmentation and monitoring to detect unusual Wi-Fi traffic patterns that might indicate exploitation attempts, while also ensuring that all affected devices receive timely security updates. This vulnerability highlights the importance of robust input validation and memory safety practices in kernel-level drivers, and represents a classic example of how seemingly minor programming errors in core system components can have severe security implications. The flaw also demonstrates the critical need for comprehensive security testing of device drivers and kernel modules, particularly those handling network communications and user-space interactions that could be exploited by malicious applications.