CVE-2023-50809: Sonos Products RCE Vulnerability

CVE-2023-50809 Overview

CVE-2023-50809 is a critical stack buffer overflow vulnerability affecting the mt_7615.ko wireless driver in certain Sonos smart speaker products. The vulnerability exists in the handling of information elements during WPA2 four-way handshake negotiation, where improper validation allows an attacker to trigger a stack buffer overflow condition. Successful exploitation can result in remote code execution within the kernel, giving an attacker complete control over the affected device.

Critical Impact

This vulnerability enables remote code execution at the kernel level in Sonos smart speakers, potentially allowing attackers to compromise home networks through IoT devices during wireless authentication.

Affected Products

• Sonos Amp (before S1 Release 11.12 and S2 Release 15.9)
• Sonos Arc, Arc SL (before S1 Release 11.12 and S2 Release 15.9)
• Sonos Beam, Beam Gen 2, Beam SL (before S1 Release 11.12 and S2 Release 15.9)
• Sonos Five (before S1 Release 11.12 and S2 Release 15.9)

Discovery Timeline

• 2024-08-12 - CVE-2023-50809 published to NVD
• 2025-03-13 - Last updated in NVD database

Technical Details for CVE-2023-50809

Vulnerability Analysis

The vulnerability resides in the mt_7615.ko wireless driver used by multiple Sonos smart speaker products. During the WPA2 four-way handshake process, the driver processes information elements (IEs) contained within EAPOL-Key frames. The driver fails to properly validate the length and content of these information elements before copying them to a stack-allocated buffer.

When an attacker provides a maliciously crafted information element with an excessive length value, the driver copies more data than the stack buffer can accommodate. This results in a classic stack buffer overflow condition (CWE-121) that corrupts adjacent stack memory, including potentially overwriting the return address and other critical control flow data.

The consequence of this vulnerability is severe: successful exploitation achieves arbitrary code execution within the kernel context. This provides the attacker with the highest privilege level on the device, enabling complete system compromise including persistent backdoor installation, network traffic interception, and lateral movement to other devices on the network.

Root Cause

The root cause is insufficient input validation in the wireless driver's information element parsing routine. Specifically, the mt_7615.ko driver does not verify that the declared length of an information element matches the actual available buffer space before performing memory copy operations. This missing bounds check allows attacker-controlled data to overflow the stack buffer during WPA2 authentication.

Attack Vector

The attack exploits the WPA2 four-way handshake mechanism, which is a fundamental part of wireless network authentication. An attacker within wireless range of a vulnerable Sonos device can initiate or intercept the handshake process and inject a malformed EAPOL-Key frame containing a specially crafted information element. The malicious frame triggers the buffer overflow when processed by the vulnerable driver.

The attack requires the attacker to be within wireless range of the target device. However, once the vulnerability is triggered, the attacker gains kernel-level code execution, making this a high-impact security issue despite the local attack vector requirement. The exploitation does not require any user interaction or prior authentication to the target network.

Detection Methods for CVE-2023-50809

Indicators of Compromise

• Unusual wireless authentication failures or repeated handshake attempts from unknown MAC addresses
• Kernel crashes or unexpected reboots of Sonos devices
• Anomalous network traffic originating from Sonos devices to external IP addresses
• Changes to device firmware or configuration not initiated by legitimate users

Detection Strategies

• Monitor wireless network logs for abnormal EAPOL-Key frame patterns or malformed authentication requests
• Implement wireless intrusion detection systems (WIDS) to detect exploitation attempts during WPA2 handshakes
• Review Sonos device firmware versions across the network to identify unpatched devices
• Analyze network traffic from IoT devices for unusual outbound connections indicating compromise

Monitoring Recommendations

• Enable logging on wireless access points and review for suspicious authentication events
• Implement network segmentation to isolate IoT devices from critical network resources
• Deploy endpoint detection capabilities that can monitor firmware integrity on connected devices
• Establish baseline network behavior for Sonos devices to detect anomalous activity

How to Mitigate CVE-2023-50809

Immediate Actions Required

• Update all affected Sonos devices to S1 Release 11.12 or later, or S2 Release 15.9 or later
• Audit your network for vulnerable Sonos products (Amp, Arc, Arc SL, Beam, Beam Gen 2, Beam SL, Five)
• Implement network segmentation to isolate IoT devices from sensitive network resources
• Monitor for security advisories from Sonos for additional guidance

Patch Information

Sonos has released firmware updates that address this vulnerability. Users should update to S1 Release 11.12 or later for S1 platform devices, or S2 Release 15.9 or later for S2 platform devices. The patches include proper validation of information element lengths during WPA2 handshake negotiation to prevent the stack buffer overflow condition.

For detailed patch information, refer to the Sonos Security Advisory 2024-0001.

Workarounds

• If immediate patching is not possible, consider temporarily disconnecting vulnerable devices from wireless networks
• Place Sonos devices on an isolated VLAN with restricted internet access until patches can be applied
• Monitor wireless network activity for suspicious authentication patterns that may indicate exploitation attempts
• Disable wireless connectivity on affected devices if wired Ethernet connectivity is available as an alternative

Sonos devices typically update automatically when connected to the internet. Ensure automatic updates are enabled in the Sonos application settings to receive security patches promptly.