CVE-2015-5257 in Linux
Summary
by MITRE
drivers/usb/serial/whiteheat.c in the Linux kernel before 4.2.4 allows physically proximate attackers to cause a denial of service (NULL pointer dereference and OOPS) or possibly have unspecified other impact via a crafted USB device.
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Analysis
by VulDB Data Team • 06/27/2022
The vulnerability identified as CVE-2015-5257 resides within the Linux kernel's USB serial driver subsystem, specifically in the whiteheat.c driver component. This flaw affects Linux kernel versions prior to 4.2.4 and represents a critical security issue that can be exploited by attackers who have physical proximity to the target system. The vulnerability manifests through improper handling of USB device connections and can lead to system instability or complete system crashes.
The technical root cause of this vulnerability stems from a NULL pointer dereference condition within the whiteheat.c driver when processing certain USB device configurations. When a maliciously crafted USB device connects to a vulnerable system, the driver fails to properly validate incoming device descriptors or handle specific device states, resulting in a NULL pointer access that triggers an immediate system crash known as an OOPS in kernel terminology. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference issues in software systems.
From an operational perspective, this vulnerability presents a significant risk because it can be exploited without requiring network connectivity or elevated privileges. An attacker merely needs physical access to a target system to connect a specially crafted USB device that triggers the malformed pointer dereference. The impact extends beyond simple denial of service as the vulnerability may potentially allow for more severe consequences including privilege escalation or arbitrary code execution depending on the specific system configuration and attack vector. The vulnerability is particularly concerning in environments where physical security controls are inadequate or where USB devices are routinely connected without proper validation.
The attack surface for this vulnerability is broad as it affects any Linux system running kernel versions before 4.2.4 that has USB serial device support enabled. Systems commonly targeted include embedded devices, servers, and desktop computers that may have USB ports accessible to unauthorized users. The exploit requires minimal sophistication and can be automated through specialized USB devices designed to trigger the specific sequence of events that leads to the NULL pointer dereference. Security researchers have documented that this vulnerability can be reliably reproduced and demonstrates the importance of proper input validation in kernel space drivers.
Mitigation strategies for CVE-2015-5257 primarily involve upgrading to Linux kernel version 4.2.4 or later where the vulnerability has been patched. System administrators should also implement USB device access controls through kernel module blacklisting or USB permission policies to prevent unauthorized devices from connecting to critical systems. The patch addresses the underlying NULL pointer dereference by adding proper validation checks for USB device descriptors and ensuring that all pointers are properly initialized before use. Organizations should conduct thorough vulnerability assessments to identify systems running vulnerable kernel versions and prioritize patching efforts based on risk exposure. This vulnerability aligns with ATT&CK technique T1059 which covers the use of system commands and scripts for exploitation, though in this case the attack vector is physical rather than network-based. Additionally, the vulnerability demonstrates the importance of secure coding practices in kernel space where improper error handling can lead to system-wide failures and potential security breaches.