CVE-2020-12447
📋 TL;DR
This CVE describes a Local File Inclusion vulnerability in Onkyo TX-NR585 network audio/video receivers that allows remote unauthenticated attackers on the same network to read sensitive system files using directory traversal techniques. The vulnerability specifically affects devices with firmware version 1000-0000-000-0008-0000 and allows reading critical files like /etc/shadow, potentially exposing password hashes.
💻 Affected Systems
- Onkyo TX-NR585
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could read the /etc/shadow file to obtain password hashes for offline cracking, potentially gaining root access to the device, then pivot to other network devices or install persistent backdoors.
Likely Case
Attackers on the local network read sensitive configuration files, extract credentials, and potentially compromise the device for further network attacks or surveillance.
If Mitigated
With proper network segmentation and access controls, the impact is limited to the device itself without lateral movement opportunities.
🎯 Exploit Status
The blog references demonstrate the exploit with simple HTTP requests using URL-encoded directory traversal sequences (%2e%2e%2f for ../).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not publicly available
Restart Required: No
Instructions:
Check Onkyo support for firmware updates. If available, download and install the latest firmware through the device's web interface or USB update method.
🔧 Temporary Workarounds
Network Segmentation
allIsolate the Onkyo device on a separate VLAN or network segment to prevent access from untrusted devices.
Access Control Lists
allConfigure firewall rules to restrict access to the device's web interface (typically port 80/443) to only trusted management stations.
🧯 If You Can't Patch
- Disable the web interface if not needed through device settings
- Change default passwords and ensure strong credentials are used for any device accounts
🔍 How to Verify
Check if Vulnerable:
Attempt to access http://[device-ip]/%2e%2e%2fetc%2fshadow or similar traversal paths. If the device returns the shadow file contents, it's vulnerable.Check Version:
Check firmware version in device web interface under Settings > System Information or similar menu.Verify Fix Applied:
After applying any mitigation, retest the same traversal paths. They should return error messages or be blocked.📡 Detection & Monitoring
Log Indicators:
- HTTP requests containing %2e%2e%2f sequences
- Unusual file access patterns to system directories
Network Indicators:
- HTTP requests to device IP with URL-encoded directory traversal patterns
- Multiple failed attempts followed by successful sensitive file access
SIEM Query:
http.url:*%2e%2e%2f* AND (dst_ip:[device_ip] OR dst_port:80 OR dst_port:443)