CVE-2020-10367: Cypress Wireless Chip Spectra Vulnerability

CVE-2020-10367 Overview

CVE-2020-10367 is a firmware vulnerability affecting certain Cypress (and Broadcom) Wireless Combo chips that allows unauthorized memory access via a "Spectra" attack when the January 2021 firmware update is not present. This side channel attack exploits the coexistence mechanism between WiFi and Bluetooth components on combo wireless chips, potentially allowing an attacker on an adjacent network to read sensitive data from memory.

Critical Impact

Attackers within adjacent network range can exploit the shared memory architecture of wireless combo chips to access sensitive information, potentially compromising confidentiality, integrity, and availability of affected devices.

Affected Products

• Cypress Wireless Combo chips (various models without January 2021 firmware update)
• Broadcom Wireless Combo chips (various models without January 2021 firmware update)
• Devices utilizing affected combo WiFi/Bluetooth chipsets (including Raspberry Pi devices)

Discovery Timeline

• 2024-11-10 - CVE CVE-2020-10367 published to NVD
• 2024-11-26 - Last updated in NVD database

Technical Details for CVE-2020-10367

Vulnerability Analysis

The "Spectra" vulnerability exploits the inherent design of wireless combo chips where WiFi and Bluetooth components share physical resources, including memory and coexistence arbitration mechanisms. This vulnerability is classified under CWE-203 (Observable Discrepancy), indicating that the attack leverages observable differences in the chip's behavior to extract sensitive information.

The attack requires the attacker to be on an adjacent network (within wireless range) and have low-level access privileges to execute. The shared resource architecture on combo chips creates a side channel that can be exploited to access memory regions that should otherwise be isolated between the WiFi and Bluetooth subsystems.

Root Cause

The root cause stems from insufficient isolation between the WiFi and Bluetooth components on wireless combo chips. The coexistence mechanism, designed to allow both wireless technologies to operate efficiently on shared hardware, does not adequately protect memory access boundaries. This architectural weakness allows one component to influence or observe the state of the other, creating an exploitable side channel.

Attack Vector

The attack vector requires adjacent network access (AV:A), meaning the attacker must be within wireless range of the target device. The attack does not require user interaction and can be performed with low-privilege access. The "Spectra" attack methodology involves:

1. Establishing a wireless connection within range of the vulnerable device
2. Manipulating the coexistence arbitration between WiFi and Bluetooth subsystems
3. Exploiting the observable timing or behavioral discrepancies to infer memory contents
4. Extracting sensitive data from the shared memory regions

The attack leverages the shared resource pool on combo chips where the WiFi and Bluetooth components compete for access, creating observable side effects that leak information about memory state. Researchers at TU Darmstadt documented this attack methodology in their security research. For detailed technical information, refer to the TU Darmstadt research publication.

Detection Methods for CVE-2020-10367

Indicators of Compromise

• Unusual wireless coexistence behavior or performance anomalies on affected devices
• Unexpected Bluetooth or WiFi disconnections during exploitation attempts
• Anomalous memory access patterns in device firmware logs if available

Detection Strategies

• Inventory all devices utilizing Cypress or Broadcom wireless combo chips and verify firmware versions
• Monitor for unusual wireless traffic patterns or connection behavior on susceptible devices
• Implement wireless intrusion detection systems to identify potential adjacent network attacks
• Review device logs for any indicators of coexistence mechanism manipulation

Monitoring Recommendations

• Deploy network monitoring tools capable of detecting adjacent network reconnaissance activities
• Establish baseline wireless performance metrics to identify anomalous behavior
• Monitor firmware update status across all affected device types in the environment
• Implement alerting for devices operating with outdated wireless chip firmware

How to Mitigate CVE-2020-10367

Immediate Actions Required

• Apply the January 2021 (or later) firmware update to all affected Cypress and Broadcom wireless combo chips
• Inventory all devices containing potentially vulnerable wireless combo chips
• Prioritize updates for devices processing sensitive information or in high-security environments
• Consider network segmentation to limit adjacent network exposure until patches can be applied

Patch Information

The January 2021 firmware update addresses this vulnerability by implementing improved isolation between WiFi and Bluetooth subsystems. For Raspberry Pi devices, the updated firmware is available through the bluez-firmware repository commit. Additional tracking information is available in the Red Hat Bug Report.

Device manufacturers should consult with Cypress/Broadcom for specific firmware update packages for their hardware configurations.

Workarounds

• Reduce wireless transmission power to limit the effective range of potential attackers
• Implement physical security controls to restrict adjacent network access where possible
• Consider disabling Bluetooth functionality on devices where it is not required, reducing the attack surface
• Deploy wireless monitoring to detect unauthorized devices attempting to exploit vulnerable chips

# Example: Check and update Raspberry Pi firmware
# Verify current firmware version
sudo apt-cache policy bluez-firmware

# Update to patched firmware version
sudo apt-get update
sudo apt-get install --only-upgrade bluez-firmware

# Reboot to apply firmware changes
sudo reboot