CVE-2023-39454
📋 TL;DR
A buffer overflow vulnerability in ELECOM wireless LAN routers allows unauthenticated attackers to execute arbitrary code remotely. This affects users of specific ELECOM router models with vulnerable firmware versions. Attackers can potentially take full control of affected devices.
💻 Affected Systems
- ELECOM WRC-1167GHBK-S
- ELECOM WRC-1167GHBK-A
- ELECOM WRC-2533GS2-B
- ELECOM WRC-2533GS2-W
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of router allowing attacker to intercept all network traffic, install persistent malware, pivot to internal network devices, and use router as botnet node.
Likely Case
Router compromise leading to network traffic interception, DNS hijacking, credential theft, and lateral movement to connected devices.
If Mitigated
Limited impact if router is behind firewall with strict inbound rules, though internal network exposure remains if exploited from within.
🎯 Exploit Status
Buffer overflow in CWE-120 suggests straightforward exploitation. No authentication required makes this highly dangerous.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware version 1.25
Vendor Advisory: https://www.elecom.co.jp/news/security/20230711-01/
Restart Required: Yes
Instructions:
1. Download firmware version 1.25 from ELECOM support site. 2. Log into router web interface. 3. Navigate to firmware update section. 4. Upload and apply new firmware. 5. Router will reboot automatically.
🔧 Temporary Workarounds
Disable WAN Management
allPrevent external access to router management interface
Log into router web interface
Navigate to Administration > Remote Management
Disable remote management/access from WAN
Network Segmentation
allIsolate router management interface to separate VLAN
Configure VLAN for management traffic only
Apply firewall rules to restrict access to management VLAN
🧯 If You Can't Patch
- Replace affected routers with patched or different vendor models
- Place routers behind dedicated firewall with strict inbound rules blocking all unnecessary ports
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in web interface under System Information or Status pageCheck Version:
Check via router web interface or SSH if enabled: show version or equivalentVerify Fix Applied:
Confirm firmware version shows 1.25 or higher after update📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts to router
- Unusual outbound connections from router
- Firmware modification logs
- Buffer overflow error messages in system logs
Network Indicators:
- Unusual traffic patterns from router to external IPs
- DNS queries to suspicious domains from router
- Port scanning originating from router
SIEM Query:
source="router_logs" AND (event_type="buffer_overflow" OR event_type="firmware_change" OR failed_logins>10)