CVE-2019-15098 in Linux
Summary
by MITRE
drivers/net/wireless/ath/ath6kl/usb.c in the Linux kernel through 5.2.8 has a NULL pointer dereference via an incomplete address in an endpoint descriptor.
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Analysis
by VulDB Data Team • 11/26/2023
The vulnerability identified as CVE-2019-15098 represents a critical NULL pointer dereference flaw within the Linux kernel's wireless networking subsystem, specifically affecting the ath6kl driver used for Qualcomm Atheros wireless chipsets. This issue exists in the USB component of the driver where the kernel fails to properly validate endpoint descriptor addresses during device initialization or configuration phases. The flaw manifests when the system processes incomplete or malformed endpoint descriptors received from wireless USB devices, leading to a scenario where a null pointer is dereferenced during the driver's endpoint setup routine. This vulnerability impacts Linux kernel versions through 5.2.8 and affects systems utilizing Qualcomm Atheros wireless USB adapters, particularly those employing the ath6kl driver for wireless connectivity.
The technical implementation of this vulnerability stems from inadequate input validation within the usb.c file of the ath6kl driver module. When a wireless USB device presents an endpoint descriptor with missing or malformed address fields, the driver code does not perform proper null checks before attempting to access the endpoint structure. This failure to validate the endpoint descriptor address field creates a path where a NULL pointer is passed to subsequent functions that expect valid memory addresses, ultimately resulting in a kernel panic or system crash. The vulnerability is classified as a classic null pointer dereference issue that falls under CWE-476, which specifically addresses NULL pointer dereference conditions in software implementations. The flaw demonstrates poor defensive programming practices where the driver assumes endpoint descriptors will always contain valid address information without proper validation mechanisms.
The operational impact of CVE-2019-15098 extends beyond simple system crashes, creating potential denial of service conditions that can affect wireless connectivity and overall system stability. An attacker with physical access to a vulnerable system or the ability to inject malicious USB devices could exploit this vulnerability to cause kernel panics, forcing system reboots and potentially disrupting critical wireless communications. In enterprise environments where wireless infrastructure is heavily relied upon, this vulnerability could lead to service interruptions and unauthorized access points that might be leveraged for further attacks. The vulnerability aligns with ATT&CK technique T1059.001 for command and control through kernel-level exploits, and T1499.004 for network denial of service attacks. Systems running affected kernel versions may experience complete wireless service outages, forcing administrators to either update kernel versions or implement temporary workarounds that disable wireless functionality.
Mitigation strategies for CVE-2019-15098 should prioritize immediate kernel updates to versions 5.3 or later where the vulnerability has been patched through proper input validation and null pointer checks in the endpoint descriptor processing code. Organizations should implement comprehensive patch management procedures to ensure all wireless-enabled systems receive the necessary updates. Additionally, security administrators should consider implementing USB device whitelisting policies to restrict which wireless USB devices can be connected to critical systems, thereby reducing the attack surface. The patch addresses the root cause by adding proper validation checks before endpoint address dereferencing and includes enhanced error handling for malformed USB descriptors. Network monitoring should be deployed to detect unusual wireless connectivity disruptions that might indicate exploitation attempts, while system administrators should maintain detailed logs of USB device connections to track potential malicious activity. This vulnerability serves as a reminder of the importance of robust input validation in kernel modules, particularly those handling external device communications where malformed input can lead to system-wide failures.