CVE-2019-15504 in Linux
Summary
by MITRE • 01/25/2023
drivers/net/wireless/rsi/rsi_91x_usb.c in the Linux kernel through 5.2.9 has a Double Free via crafted USB device traffic (which may be remote via usbip or usbredir).
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Analysis
by VulDB Data Team • 12/01/2023
The vulnerability identified as CVE-2019-15504 represents a critical double free error in the Linux kernel's wireless driver subsystem, specifically within the RSI (Ralink Silicon Image) 91x USB driver implementation. This flaw exists in the drivers/net/wireless/rsi/rsi_91x_usb.c file and affects Linux kernel versions through 5.2.9, creating a potential pathway for remote code execution through malicious USB device traffic. The vulnerability stems from improper memory management within the driver's handling of USB device communications, where the same memory block gets freed twice under specific conditions triggered by crafted USB packets.
The technical nature of this vulnerability aligns with CWE-415, which describes improper double-free conditions in software systems. The flaw occurs when the driver processes malformed USB traffic that causes it to attempt to free the same memory allocation twice, leading to memory corruption that can be exploited by attackers. This type of vulnerability is particularly dangerous because it can be triggered remotely through USBIP (USB over IP) or usbredir protocols, which allow USB devices to be shared across network connections. Attackers can craft malicious USB packets that, when processed by an affected kernel, trigger the double free condition and potentially execute arbitrary code with kernel privileges.
The operational impact of CVE-2019-15504 extends beyond simple system crashes, as it represents a serious escalation vector for attackers who can leverage remote USB connections to compromise systems. Systems running affected kernel versions are vulnerable to attacks that could result in complete system compromise, data theft, or persistent backdoor installation. The remote exploitation capability through USBIP or usbredir protocols means that attackers don't need physical access to target systems, making this vulnerability particularly concerning for enterprise environments where USB device sharing is common. Organizations with systems that accept USB connections or use USBIP services are at risk, as the vulnerability can be triggered by simply connecting a malicious USB device or through network-based USB redirection services.
Mitigation strategies for CVE-2019-15504 should prioritize immediate kernel updates to versions 5.3 or later where the double free issue has been resolved through proper memory management fixes. System administrators should disable USBIP services and usbredir functionality when not required, particularly in environments where untrusted USB devices might be connected. Network segmentation and USB device access controls should be implemented to limit potential attack vectors, while monitoring systems should be configured to detect unusual USB device activity. The vulnerability also highlights the importance of maintaining up-to-date kernel versions and implementing robust security practices for USB device management, as outlined in various security frameworks including the NIST Cybersecurity Framework and ISO 27001 standards for information security management. Additionally, organizations should consider implementing endpoint protection solutions that can detect and prevent exploitation attempts targeting kernel-level vulnerabilities.