CVE-2016-7915 in Android
Summary
by MITRE
The hid_input_field function in drivers/hid/hid-core.c in the Linux kernel before 4.6 allows physically proximate attackers to obtain sensitive information from kernel memory or cause a denial of service (out-of-bounds read) by connecting a device, as demonstrated by a Logitech DJ receiver.
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Analysis
by VulDB Data Team • 09/30/2022
The vulnerability identified as CVE-2016-7915 represents a critical security flaw in the Linux kernel's Human Interface Device (HID) subsystem that affects versions prior to 4.6. This issue resides within the hid_input_field function located in drivers/hid/hid-core.c, which is responsible for processing input reports from HID devices such as keyboards, mice, and other peripheral devices. The vulnerability manifests when a maliciously crafted HID device is physically connected to a target system, exploiting a flaw in how the kernel handles input field processing and validation. The specific threat vector involves an attacker positioning themselves in close physical proximity to a target system and connecting a specially crafted HID device, such as the Logitech DJ receiver demonstrated in the exploit.
The technical nature of this vulnerability constitutes an out-of-bounds read condition that can lead to two distinct but serious security implications. The primary concern is information disclosure where attackers can read sensitive data from kernel memory spaces that should remain protected from user-space access. This occurs due to insufficient bounds checking in the hid_input_field function when processing input reports from connected HID devices. The vulnerability stems from a lack of proper validation of input field sizes and offsets, allowing an attacker to craft input reports that reference memory locations beyond the intended buffer boundaries. This type of flaw is classified as a CWE-125: Out-of-bounds Read according to the Common Weakness Enumeration taxonomy, which specifically addresses situations where a program reads data past the end of a buffer or array.
The operational impact of CVE-2016-7915 extends beyond simple information disclosure to include potential denial of service conditions that can severely compromise system availability. When exploited, the out-of-bounds read can cause the kernel to access invalid memory locations, potentially resulting in kernel panics, system crashes, or other instability issues that render the affected system unusable. The physical proximity requirement for exploitation makes this vulnerability particularly concerning in environments where untrusted devices might be connected to systems, such as public computers, kiosks, or shared workstations. Attackers can leverage this vulnerability to gain unauthorized access to kernel memory contents, potentially extracting sensitive information such as cryptographic keys, passwords, or other confidential data stored in memory. The ATT&CK framework categorizes this type of vulnerability under T1068: Exploitation for Privilege Escalation and T1547.001: Registry Run Keys / Startup Folder, as it can be used to establish persistent access or escalate privileges through kernel memory access.
Mitigation strategies for CVE-2016-7915 primarily focus on updating the Linux kernel to version 4.6 or later where the vulnerability has been addressed through proper bounds checking implementation. System administrators should prioritize patching affected systems and ensuring that all kernel components are up to date with the latest security releases. Additional protective measures include implementing device whitelisting policies that restrict which HID devices can be connected to critical systems, disabling unnecessary HID drivers when not required, and monitoring for suspicious device connections. The vulnerability also highlights the importance of input validation and proper memory management in kernel space operations, emphasizing the need for comprehensive security testing of kernel subsystems. Organizations should consider implementing security controls such as kernel module signing, secure boot configurations, and runtime monitoring to detect and prevent exploitation attempts. The fix implemented in kernel version 4.6 specifically addresses the missing bounds checking by ensuring that input field processing validates the size and offset parameters before accessing kernel memory, thereby preventing the out-of-bounds read conditions that enabled both information disclosure and denial of service attacks.