CVE-2020-24396
📋 TL;DR
This vulnerability exposes sensitive SSH keys within downloadable firmware images for homee Brain Cube v2 devices, allowing attackers to use the support server as a SOCKS proxy. This affects users of homee Brain Cube v2 devices with firmware versions 2.28.2 and 2.28.4, potentially enabling unauthorized network access and data exfiltration.
💻 Affected Systems
- homee Brain Cube v2
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain persistent access to internal networks, pivot to other systems, exfiltrate sensitive data, and use the compromised device for further attacks.
Likely Case
Unauthorized use of the device as a SOCKS proxy for anonymized attacks, potential data interception, and network reconnaissance.
If Mitigated
Limited to isolated network segments with no sensitive data, minimal impact with proper network segmentation and monitoring.
🎯 Exploit Status
Exploitation involves downloading firmware, extracting SSH keys, and using them to access the device. Public advisory includes technical details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 2.28.4
Vendor Advisory: https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2020-027.txt
Restart Required: Yes
Instructions:
1. Check current firmware version. 2. Download and install latest firmware from vendor. 3. Restart device. 4. Verify SSH keys are no longer in firmware images.
🔧 Temporary Workarounds
Disable SSH access
linuxTemporarily disable SSH service on affected devices to prevent key-based access.
systemctl stop ssh
systemctl disable ssh
Network isolation
allPlace devices in isolated VLAN with strict firewall rules limiting outbound connections.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate affected devices from sensitive systems
- Monitor for unusual outbound connections and SSH authentication attempts
🔍 How to Verify
Check if Vulnerable:
Download firmware image for your device version and check if SSH private keys are present in the filesystem.Check Version:
Check device web interface or use vendor-specific CLI command to display firmware versionVerify Fix Applied:
Download updated firmware and verify SSH keys are no longer present in the image. Check device SSH configuration for key-based authentication changes.📡 Detection & Monitoring
Log Indicators:
- Unusual SSH login attempts
- Unexpected SOCKS proxy connections
- Firmware download requests from unknown IPs
Network Indicators:
- Outbound connections from device to unusual destinations
- SOCKS protocol traffic on non-standard ports
- SSH connections to device from external IPs
SIEM Query:
source="device_logs" AND (event="ssh_login" AND user!="authorized_user") OR (protocol="socks" AND dest_ip!="allowed_proxy")🔗 References
- https://cwe.mitre.org/data/definitions/522.html
- https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2020-027.txt
- https://www.syss.de/pentest-blog/
- https://cwe.mitre.org/data/definitions/522.html
- https://www.syss.de/fileadmin/dokumente/Publikationen/Advisories/SYSS-2020-027.txt
- https://www.syss.de/pentest-blog/
