CVE-2023-30280
📋 TL;DR
A buffer overflow vulnerability in Netgear R6900, R6700v3, and R6700 routers allows remote attackers to execute arbitrary code or cause denial of service by sending specially crafted requests to the fwSchedule.cgi page. This affects users running vulnerable firmware versions on these specific router models. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Netgear R6900
- Netgear R6700v3
- Netgear R6700
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote attacker gains full administrative control of the router, installs persistent malware, intercepts all network traffic, and uses the compromised device as a pivot point to attack internal network resources.
Likely Case
Remote attacker executes arbitrary code to disrupt router functionality, modify configurations, or install cryptocurrency miners or botnet malware.
If Mitigated
Attack attempts are blocked at network perimeter, and even if successful, network segmentation limits lateral movement to isolated segments.
🎯 Exploit Status
Exploitation requires sending crafted HTTP requests to the vulnerable endpoint. Public proof-of-concept code exists in GitHub repositories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Netgear security advisories for latest patched versions
Vendor Advisory: https://www.netgear.com/about/security/
Restart Required: Yes
Instructions:
1. Log into router admin interface. 2. Navigate to firmware update section. 3. Check for available updates. 4. Download and install latest firmware from Netgear support site. 5. Reboot router after update completes.
🔧 Temporary Workarounds
Block external access to router admin interface
linuxConfigure firewall rules to block external WAN access to router administration ports (typically 80/443)
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Disable remote management
allTurn off remote management feature in router settings to prevent external access to admin interface
🧯 If You Can't Patch
- Isolate affected routers in separate network segment with strict firewall rules
- Implement network monitoring to detect exploitation attempts and block malicious IPs
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under Advanced > Administration > Router UpdateCheck Version:
curl -s http://router-ip/currentsetting.htm | grep firmwareVerify Fix Applied:
Confirm firmware version is updated to a version later than those listed in affected systems📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to /fwSchedule.cgi
- Multiple failed buffer overflow attempts in router logs
- Router reboot events following suspicious requests
Network Indicators:
- HTTP requests with unusually long getInputData parameters
- Traffic patterns suggesting router compromise (unexpected outbound connections)
SIEM Query:
source="router_logs" AND (uri="/fwSchedule.cgi" OR message="buffer overflow")