CVE-2017-16527 in Linux
Summary
by MITRE
sound/usb/mixer.c in the Linux kernel before 4.13.8 allows local users to cause a denial of service (snd_usb_mixer_interrupt use-after-free and system crash) or possibly have unspecified other impact via crafted system calls.
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Analysis
by VulDB Data Team • 01/06/2023
The vulnerability identified as CVE-2017-16527 resides within the Linux kernel's USB audio subsystem, specifically in the sound/usb/mixer.c file. This flaw represents a critical use-after-free vulnerability that affects Linux kernel versions prior to 4.13.8, creating a significant security risk for systems utilizing USB audio devices. The vulnerability manifests when local attackers can manipulate crafted system calls to trigger memory management errors within the USB audio mixer driver, potentially leading to system instability and denial of service conditions.
The technical implementation of this vulnerability involves improper memory handling within the snd_usb_mixer_interrupt function where a freed memory reference is accessed after the associated memory block has been deallocated. This use-after-free condition occurs when the kernel processes USB audio interrupt data and fails to properly validate the state of memory objects during concurrent access scenarios. The flaw is particularly dangerous because it can be exploited through local user accounts without requiring elevated privileges, making it accessible to any user with system access. According to CWE-416, this represents a classic use-after-free vulnerability where the kernel fails to properly manage object lifecycles in the USB audio subsystem, specifically within the mixer component that handles USB audio device configurations and control messages.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable more sophisticated attacks. When exploited, the use-after-free condition can cause system crashes, kernel oops messages, and complete system instability that may require manual rebooting. The vulnerability's potential for unspecified other impacts suggests that attackers might leverage this flaw to escalate privileges or execute arbitrary code, particularly given that the USB audio subsystem typically runs with kernel-level privileges. This represents a significant concern for enterprise environments where audio devices are commonly used and where local privilege escalation could provide attackers with elevated system access. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting kernel-level components and system services that handle hardware device interactions.
Mitigation strategies for CVE-2017-16527 focus primarily on kernel version updates to 4.13.8 or later, which contain the necessary patches to address the use-after-free condition in the USB audio mixer driver. System administrators should prioritize immediate deployment of patched kernel versions across all affected systems, particularly those running audio-intensive workloads or serving as audio endpoints in networked environments. Additionally, implementing runtime protections such as kernel address space layout randomization and stack canaries can provide additional defense-in-depth measures. Organizations should also consider restricting local user access to audio device interfaces when possible, as this reduces the attack surface for exploitation. The vulnerability highlights the importance of maintaining current kernel versions and implementing comprehensive patch management processes, as the flaw existed in multiple kernel releases and could be exploited across various hardware configurations. Security monitoring should include detection of kernel oops messages and system crashes related to USB audio subsystems, as these may indicate exploitation attempts.