CVE-2018-12706
📋 TL;DR
CVE-2018-12706 is a critical buffer overflow vulnerability in DIGISOL DG-BR4000NG routers that allows remote attackers to execute arbitrary code by sending a specially crafted HTTP request with an overly long Authorization header. This affects all users of vulnerable DIGISOL DG-BR4000NG devices, potentially giving attackers full control of the router.
💻 Affected Systems
- DIGISOL DG-BR4000NG
📦 What is this software?
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network traffic interception, credential theft, and use as a pivot point for attacking internal networks.
Likely Case
Remote code execution allowing attackers to modify router settings, intercept traffic, or use the device for further attacks.
If Mitigated
Limited impact if device is behind firewall with restricted HTTP access, though still vulnerable to internal threats.
🎯 Exploit Status
Exploit code is publicly available and requires minimal technical skill to execute against vulnerable devices.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check with DIGISOL for latest firmware
Vendor Advisory: https://www.digisol.com/
Restart Required: Yes
Instructions:
1. Visit DIGISOL support website. 2. Download latest firmware for DG-BR4000NG. 3. Access router web interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable HTTP/HTTPS access to router management interface
Access router CLI via SSH/Telnet
Navigate to web interface settings
Disable HTTP/HTTPS management
Restrict Management Access
allLimit web interface access to specific IP addresses only
Configure firewall rules to restrict port 80/443 access
Set up management VLAN
🧯 If You Can't Patch
- Isolate device on separate network segment with strict firewall rules
- Implement network-based intrusion detection to monitor for exploit attempts
🔍 How to Verify
Check if Vulnerable:
Test by sending HTTP request with Authorization header exceeding normal length to router web interfaceCheck Version:
Check web interface status page or use CLI command: show versionVerify Fix Applied:
Verify firmware version is updated and test exploit no longer works📡 Detection & Monitoring
Log Indicators:
- Unusually long HTTP Authorization headers in web server logs
- Multiple failed login attempts with malformed headers
Network Indicators:
- HTTP requests with Authorization headers > 1000 bytes
- Traffic to router web interface from unexpected sources
SIEM Query:
http.method=POST AND http.headers.authorization.length>1000 AND dest_ip=[router_ip]