CVE-2017-16530 in Linux
Summary
by MITRE
The uas driver in the Linux kernel before 4.13.6 allows local users to cause a denial of service (out-of-bounds read and system crash) or possibly have unspecified other impact via crafted system calls, related to drivers/usb/storage/uas-detect.h and drivers/usb/storage/uas.c.
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Analysis
by VulDB Data Team • 01/06/2023
The vulnerability identified as CVE-2017-16530 represents a critical security flaw within the Linux kernel's USB Attached SCSI driver implementation, specifically affecting versions prior to 4.13.6. This issue resides in the uas driver component that handles USB mass storage devices, particularly those implementing the USB Attached SCSI protocol. The vulnerability stems from insufficient input validation and boundary checking within the driver's handling of system calls, creating a pathway for malicious local users to exploit the kernel's USB storage subsystem. The affected files uas-detect.h and uas.c contain logic that fails to properly validate the size and structure of incoming USB commands, leading to potential memory access violations.
The technical nature of this vulnerability manifests as an out-of-bounds read condition that can trigger a system crash or complete kernel panic. When a local attacker crafts specific system calls that manipulate the USB storage driver's behavior, the kernel's memory management routines encounter invalid memory access patterns that result in immediate system termination. This type of vulnerability falls under the CWE-125 Out-of-bounds Read classification, where the kernel attempts to read memory beyond the allocated buffer boundaries. The attack vector requires local system access but does not necessitate elevated privileges, making it particularly concerning as it can be exploited by any user with access to the system. The potential impact extends beyond simple denial of service, as the unspecified other impacts could include information disclosure or privilege escalation depending on the specific memory corruption patterns.
From an operational perspective, this vulnerability creates significant risk for Linux systems that utilize USB mass storage devices, particularly those implementing the UAS protocol. The attack requires only local user access, which means that any user account on the system could potentially exploit this flaw to cause system instability or complete system crashes. This makes the vulnerability particularly dangerous in multi-user environments or systems where user accounts are not properly secured. The vulnerability affects systems that have USB storage devices connected and active, including servers, desktop computers, and embedded systems that rely on USB mass storage functionality. The impact on system availability can be severe, as a successful exploitation results in immediate system termination rather than a more subtle compromise. This aligns with ATT&CK technique T1499.001 for Network Denial of Service and represents a classic kernel-level exploit that can be classified under the broader category of privilege escalation through kernel exploitation.
Mitigation strategies for CVE-2017-16530 primarily focus on kernel version updates and system hardening measures. The most effective immediate solution is upgrading to Linux kernel version 4.13.6 or later, which contains the necessary patches to address the out-of-bounds read conditions in the uas driver. System administrators should prioritize patching critical systems and ensuring that all USB storage devices are running on patched kernel versions. Additionally, implementing kernel lockdown mechanisms and restricting local user access to USB devices can provide additional defense-in-depth. The vulnerability demonstrates the importance of proper input validation in kernel drivers and highlights the need for comprehensive testing of device drivers against malformed input conditions. Security monitoring should include detection of unusual system crashes or kernel oops messages that might indicate exploitation attempts. Organizations should also consider disabling USB mass storage support entirely if the functionality is not required, as this removes the attack surface entirely and provides a definitive mitigation strategy.