CVE-2016-6676 in Android
Summary
by MITRE
Off-by-one error in CORE/HDD/src/wlan_hdd_cfg.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 GET_CFG ioctl call, aka Android internal bug 30874066 and Qualcomm internal bug CR 1000853.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability identified as CVE-2016-6676 represents a critical off-by-one error within the Qualcomm Wi-Fi driver component of Android operating systems. This flaw exists in the CORE/HDD/src/wlan_hdd_cfg.c file and specifically affects devices running Android versions prior to October 5, 2016, including Nexus 5X and Android One devices. The vulnerability stems from improper boundary checking during ioctl command processing, creating a condition where an attacker can manipulate memory access patterns through crafted applications. The issue manifests when a malicious application invokes a GET_CFG ioctl call, which triggers the flawed buffer handling mechanism within the wireless driver subsystem. This type of vulnerability falls under the CWE-129 category of Improper Validation of Array Index, specifically manifesting as an off-by-one error that allows for unauthorized memory access.
The technical exploitation of this vulnerability occurs through the manipulation of ioctl (input/output control) system calls within the Android kernel's wireless subsystem. When a crafted application executes a GET_CFG ioctl call, the driver's configuration handling code fails to properly validate the buffer boundaries, resulting in a potential buffer overflow condition. The off-by-one error specifically affects how the driver calculates array indices during configuration parameter retrieval, allowing an attacker to write beyond the allocated buffer space. This memory corruption can be leveraged to execute arbitrary code with elevated privileges or to cause a system crash resulting in denial of service. The vulnerability demonstrates characteristics consistent with the ATT&CK technique T1068 which involves exploiting legitimate credentials or system access to gain higher privileges, and T1499 which involves disrupting availability through system resource exhaustion or corruption.
The operational impact of CVE-2016-6676 extends beyond simple privilege escalation to encompass potential system instability and unauthorized access to wireless networking capabilities. An attacker with local application-level access can exploit this vulnerability to compromise the integrity of the device's wireless subsystem, potentially gaining access to sensitive network configurations or using the compromised driver to establish persistent access to wireless networks. The buffer overflow condition creates a predictable memory corruption pattern that can be reliably exploited across affected device models, making it particularly dangerous for widespread deployment. The vulnerability affects the core wireless driver functionality, meaning that successful exploitation could result in complete loss of wireless connectivity or unauthorized network access. Additionally, the nature of the flaw in the kernel-level driver component means that any successful exploitation would likely result in system-wide compromise rather than isolated application-level issues.
Mitigation strategies for CVE-2016-6676 primarily focus on updating affected Android devices to patched versions released by Google and Qualcomm. Device manufacturers should implement immediate security updates that correct the boundary checking logic in the wlan_hdd_cfg.c file, ensuring proper validation of array indices during ioctl processing. System administrators and security teams should prioritize patching affected devices, particularly those in enterprise environments where wireless connectivity is critical. Network monitoring solutions should be enhanced to detect anomalous ioctl call patterns that might indicate exploitation attempts. The vulnerability highlights the importance of proper input validation in kernel space drivers and reinforces the need for comprehensive security testing of system-level components. Organizations should also implement application whitelisting policies to prevent unauthorized applications from making low-level ioctl calls that could trigger similar vulnerabilities. Device manufacturers should consider implementing additional runtime protections such as stack canaries or memory protection mechanisms to detect and prevent buffer overflow exploitation attempts. The remediation process should include thorough regression testing to ensure that security patches do not negatively impact wireless functionality or device performance.