CVE-2016-2185 in Linux
Summary
by MITRE
The ati_remote2_probe function in drivers/input/misc/ati_remote2.c in the Linux kernel before 4.5.1 allows physically proximate attackers to cause a denial of service (NULL pointer dereference and system crash) via a crafted endpoints value in a USB device descriptor.
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Analysis
by VulDB Data Team • 07/10/2022
The vulnerability identified as CVE-2016-2185 resides within the Linux kernel's input subsystem, specifically in the ati_remote2 driver component. This flaw affects kernel versions prior to 4.5.1 and represents a critical denial of service vulnerability that can be exploited by attackers who are physically proximate to the target system. The vulnerability manifests in the ati_remote2_probe function which is responsible for probing and initializing ATI remote control devices connected via USB. The issue stems from inadequate input validation within the device descriptor processing logic, creating a scenario where maliciously crafted USB device descriptors can trigger system instability.
The technical exploitation of this vulnerability occurs when a USB device presents a malformed endpoints value in its device descriptor during the probe phase. The ati_remote2_probe function fails to properly validate this endpoint information before attempting to dereference pointers associated with the endpoint configuration. This NULL pointer dereference results in an immediate system crash and complete denial of service for the affected system. The vulnerability is particularly concerning because it requires only physical proximity to the target device, making it accessible to attackers who can physically interact with the system. The flaw aligns with CWE-476 which describes NULL pointer dereference conditions, and represents a classic case of insufficient input validation in kernel space code.
From an operational perspective, this vulnerability presents significant risks for systems that rely on USB input devices or operate in environments where physical security cannot be guaranteed. The impact extends beyond simple service disruption as the system crash can lead to data loss, service interruption, and potential security implications in environments where system availability is critical. Attackers can exploit this vulnerability without requiring elevated privileges or network access, making it particularly dangerous in shared or public computing environments. The vulnerability is categorized under the ATT&CK technique T1499.004 which covers network denial of service attacks, though in this case the attack vector is physical rather than network-based. Organizations running kernel versions prior to 4.5.1 face a substantial risk of system compromise through this vulnerability.
The recommended mitigation strategy involves upgrading to Linux kernel version 4.5.1 or later where the vulnerability has been addressed through proper input validation in the ati_remote2_probe function. System administrators should also implement physical security measures to prevent unauthorized USB device insertion, particularly in sensitive environments. Additional mitigations include disabling the ati_remote2 driver module if USB remote control functionality is not required, and implementing proper USB device authorization policies. The fix implemented in the patched kernel versions ensures that endpoint values in USB device descriptors are properly validated before any pointer dereference operations occur, preventing the NULL pointer dereference condition that leads to system crashes. Organizations should conduct comprehensive vulnerability assessments to identify systems running vulnerable kernel versions and prioritize patching efforts accordingly.