CVE-2023-33627
📋 TL;DR
This CVE describes a stack overflow vulnerability in H3C Magic R300 routers via the UpdateSnat interface at /goform/aspForm. Attackers can exploit this to execute arbitrary code or cause denial of service. Only users of the specific H3C router model and version are affected.
💻 Affected Systems
- H3C Magic R300
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, network infiltration, and persistent backdoor installation.
Likely Case
Denial of service causing router crashes and network disruption, potentially requiring physical reset.
If Mitigated
Limited impact if network segmentation isolates the router and strict access controls prevent external exploitation.
🎯 Exploit Status
Public proof-of-concept exists on hackmd.io showing exploitation details. The vulnerability requires no authentication and has straightforward exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: No official vendor advisory found
Restart Required: Yes
Instructions:
1. Check H3C official website for firmware updates
2. If update available, download and verify checksum
3. Access router web interface
4. Navigate to firmware update section
5. Upload new firmware file
6. Wait for update to complete and router to reboot
🔧 Temporary Workarounds
Disable web management interface
allPrevent access to the vulnerable /goform/aspForm endpoint by disabling the web management interface
Access router CLI via SSH/Telnet
Enter configuration mode
Disable web management service
Network segmentation and ACLs
allRestrict access to router management interface using firewall rules
Configure firewall to block external access to port 80/443
Allow management only from specific trusted IPs
🧯 If You Can't Patch
- Isolate the router in a dedicated VLAN with strict access controls
- Implement network monitoring for exploitation attempts and anomalous traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface at System Status > Firmware Version or via CLI command 'display version'Check Version:
display versionVerify Fix Applied:
Verify firmware version has changed from R300-2100MV100R004 to a newer version📡 Detection & Monitoring
Log Indicators:
- Multiple POST requests to /goform/aspForm with large payloads
- Router crash/reboot logs
- Unusual process creation in system logs
Network Indicators:
- HTTP POST requests to /goform/aspForm with oversized data
- Sudden loss of connectivity to router management interface
- Abnormal outbound connections from router
SIEM Query:
source="router_logs" AND (url="/goform/aspForm" AND content_length>1000) OR event="system_reboot"