CVE-2015-4002 in Linux
Summary
by MITRE
drivers/staging/ozwpan/ozusbsvc1.c in the OZWPAN driver in the Linux kernel through 4.0.5 does not ensure that certain length values are sufficiently large, which allows remote attackers to cause a denial of service (system crash or large loop) or possibly execute arbitrary code via a crafted packet, related to the (1) oz_usb_rx and (2) oz_usb_handle_ep_data functions.
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Analysis
by VulDB Data Team • 05/20/2022
The vulnerability identified as CVE-2015-4002 resides within the OZWPAN driver component of the Linux kernel, specifically in the file drivers/staging/ozwpan/ozusbsvc1.c. This driver facilitates communication with certain USB-based wireless networking devices, particularly those implementing the OZ7255 and similar chipsets. The flaw manifests in the improper validation of packet length parameters during USB data processing operations, creating a critical security gap that affects Linux kernel versions up to 4.0.5. The vulnerability is particularly concerning because it operates at the kernel level, providing attackers with potential pathways to compromise system integrity and availability.
The technical implementation flaw occurs within two primary functions: oz_usb_rx and oz_usb_handle_ep_data, which handle USB receive operations and endpoint data processing respectively. These functions fail to adequately validate the length fields contained within incoming USB packets before proceeding with data processing operations. When malformed packets containing excessively large or malformed length values are received, the driver's processing logic can become trapped in infinite loops or cause memory corruption. This improper validation creates a condition where attackers can craft specific USB packets that, when processed by the vulnerable driver, trigger buffer overflows or excessive loop iterations. The vulnerability falls under the CWE-129 weakness category, which specifically addresses insufficient validation of length values in buffer operations, making it a classic example of improper input validation that can lead to both denial of service and potential code execution scenarios.
The operational impact of this vulnerability extends beyond simple system crashes, presenting attackers with opportunities for both persistent denial of service and arbitrary code execution. When the driver encounters packets with oversized length values, it can enter infinite loops during packet processing, consuming system resources and eventually causing the entire system to become unresponsive or crash entirely. In some exploitation scenarios, particularly when attackers can control the memory layout, the vulnerability may allow for arbitrary code execution with kernel-level privileges. This presents a significant threat to systems relying on USB wireless networking capabilities, as the attack can be executed remotely through USB device connections, potentially affecting servers, desktops, and embedded systems. The vulnerability aligns with ATT&CK technique T1059.007, which covers the execution of commands through kernel modules, and T1499.004, which addresses network denial of service attacks through malformed packet processing.
Mitigation strategies for CVE-2015-4002 should focus on both immediate patching and operational security measures. The most effective solution involves upgrading to a Linux kernel version that contains the appropriate fixes, typically kernel versions 4.1 and later where the validation logic has been corrected. System administrators should also implement USB device access controls through udev rules to restrict which devices can connect to critical systems, particularly disabling the OZWPAN driver on systems where it is not required. Network segmentation and monitoring can help detect anomalous USB traffic patterns that might indicate exploitation attempts. Additionally, organizations should consider implementing kernel module signing requirements and disabling unnecessary kernel drivers through kernel configuration options to reduce the attack surface. The vulnerability demonstrates the critical importance of proper input validation in kernel space code and serves as a reminder of how seemingly minor validation flaws can have catastrophic consequences in operating system components.