CVE-2021-20621
📋 TL;DR
This CSRF vulnerability in Aterm WG2600HP and WG2600HP2 routers allows attackers to trick authenticated administrators into performing unintended actions. Attackers can hijack administrator sessions to change router settings, potentially compromising network security. All users running affected firmware versions are vulnerable.
💻 Affected Systems
- Aterm WG2600HP
- Aterm WG2600HP2
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router takeover allowing attacker to change DNS settings, firewall rules, credentials, or enable remote administration, leading to full network compromise and data interception.
Likely Case
Router configuration changes enabling unauthorized access, network redirection, or credential theft.
If Mitigated
Limited impact if CSRF protections are implemented or administrators use separate browser sessions for router management.
🎯 Exploit Status
CSRF attacks are well-understood and easy to implement. Requires administrator to be authenticated and visit malicious page.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: WG2600HP firmware Ver1.0.3 and later, WG2600HP2 firmware Ver1.0.3 and later
Vendor Advisory: https://www.aterm.jp/support/tech/2019/0328.html
Restart Required: Yes
Instructions:
1. Download latest firmware from Aterm support site. 2. Log into router web interface. 3. Navigate to firmware update section. 4. Upload and apply new firmware. 5. Router will restart automatically.
🔧 Temporary Workarounds
CSRF Token Implementation
allAdd CSRF tokens to router administration forms if customizing interface
Browser Session Management
allUse separate browser profiles or private browsing for router administration
🧯 If You Can't Patch
- Restrict router administration to dedicated management VLAN or isolated network
- Implement web application firewall with CSRF protection rules
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System Information or Status pageCheck Version:
No CLI command - check via web interface at http://router-ip/status.html or similarVerify Fix Applied:
Verify firmware version shows Ver1.0.3 or higher after update📡 Detection & Monitoring
Log Indicators:
- Multiple configuration changes from same IP in short timeframe
- Unusual administrator actions during normal business hours
Network Indicators:
- Unexpected DNS server changes
- New firewall rules allowing external access
SIEM Query:
source="router-logs" action="config_change" count by src_ip > threshold