CVE-2008-3496 in Linux
Summary
by MITRE
Buffer overflow in format descriptor parsing in the uvc_parse_format function in drivers/media/video/uvc/uvc_driver.c in uvcvideo in the video4linux (V4L) implementation in the Linux kernel before 2.6.26.1 has unknown impact and attack vectors.
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Analysis
by VulDB Data Team • 08/17/2019
The vulnerability identified as CVE-2008-3496 represents a critical buffer overflow condition within the Linux kernel's video4linux (V4L) subsystem specifically affecting the uvcvideo driver. This flaw exists in the uvc_parse_format function located in drivers/media/video/uvc/uvc_driver.c, which is responsible for parsing format descriptors from USB video devices. The vulnerability manifests during the processing of USB video device configuration data where the driver fails to properly validate the size of format descriptors before copying them into fixed-size buffers. This improper input validation creates a scenario where maliciously crafted USB video device descriptors could trigger a buffer overflow condition, potentially allowing attackers to execute arbitrary code with kernel-level privileges. The vulnerability affects Linux kernel versions prior to 2.6.26.1, making it particularly concerning given the widespread use of these kernel versions in various embedded systems and server environments. The buffer overflow occurs in the context of USB video device enumeration and configuration, which means that exploitation could occur simply through the connection of a malicious USB video device to a vulnerable system.
The technical nature of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. The flaw represents a classic case of inadequate bounds checking in kernel space code where the uvc_parse_format function does not sufficiently validate the length of incoming format descriptor data before performing memory operations. This allows an attacker with physical access to a system or the ability to present a malicious USB video device to the system to potentially overwrite adjacent memory locations. The attack surface is particularly concerning because USB devices are commonly connected to systems without requiring special privileges, and the vulnerability can be triggered during normal device enumeration processes. The impact remains classified as unknown due to the complexity of determining exactly how exploitation could occur, though the potential for privilege escalation to kernel mode is significant.
The operational impact of CVE-2008-3496 extends beyond simple privilege escalation as it represents a fundamental security weakness in the Linux kernel's USB video subsystem that could enable attackers to gain complete control over affected systems. Systems running vulnerable kernel versions are at risk of being compromised through USB-connected devices, which could be particularly dangerous in enterprise environments where USB devices are frequently used for data transfer, storage, or peripheral connectivity. The vulnerability could be exploited in various attack scenarios including physical access attacks where an attacker connects malicious USB devices, or potentially through social engineering attacks where users are tricked into connecting compromised USB video devices. The attack vectors are particularly concerning because they can be initiated without requiring elevated privileges or special user interaction beyond the simple connection of a USB device. This makes the vulnerability particularly dangerous in environments where USB device access is not restricted or monitored.
Mitigation strategies for CVE-2008-3496 primarily focus on immediate kernel updates to versions 2.6.26.1 or later where the vulnerability has been patched. System administrators should prioritize updating all systems running vulnerable kernel versions to prevent exploitation. Additional mitigations include implementing USB device access controls through kernel parameters such as disabling USB auto-loading or restricting USB device access through device-specific permissions. The patch for this vulnerability typically involves adding proper bounds checking to ensure that format descriptor lengths do not exceed allocated buffer sizes during parsing operations. Organizations should also consider implementing USB device whitelisting policies to prevent unknown or untrusted USB video devices from being connected to critical systems. From an ATT&CK perspective, this vulnerability maps to techniques involving privilege escalation and defense evasion through kernel-level modifications, making it particularly relevant for organizations implementing security controls focused on kernel integrity and USB device management. The vulnerability demonstrates the importance of proper input validation in kernel space code and highlights the need for comprehensive security testing of device drivers in operating system implementations.