CVE-2022-50800
📋 TL;DR
H3C SSL VPN has a user enumeration vulnerability that allows attackers to determine valid usernames by analyzing login response differences. Attackers can send POST requests with various usernames to the login_submit.cgi endpoint and observe response messages to identify existing accounts. This affects organizations using vulnerable H3C SSL VPN appliances.
💻 Affected Systems
- H3C SSL VPN
⚠️ 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
Attackers can enumerate all valid usernames, enabling targeted credential attacks, password spraying, or social engineering campaigns against identified users.
Likely Case
Attackers identify valid usernames, increasing success rates for subsequent brute-force or credential stuffing attacks against the VPN portal.
If Mitigated
Limited to username discovery only; attackers still need valid credentials for VPN access if proper authentication controls exist.
🎯 Exploit Status
Simple HTTP POST requests with different usernames; response analysis can be automated
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in public references; check H3C vendor advisory
Vendor Advisory: https://www.h3c.com
Restart Required: No
Instructions:
1. Check H3C vendor advisory for specific patch details. 2. Apply recommended firmware update. 3. Verify the login_submit.cgi endpoint no longer leaks username existence information.
🔧 Temporary Workarounds
Implement WAF Rules
allBlock or rate-limit requests to login_submit.cgi endpoint to prevent automated enumeration
Modify Login Responses
allConfigure VPN to return identical response messages for both valid and invalid usernames
🧯 If You Can't Patch
- Implement network segmentation to restrict VPN access to trusted IP ranges only
- Enable multi-factor authentication (MFA) to mitigate risk from credential attacks following username enumeration
🔍 How to Verify
Check if Vulnerable:
Send POST requests to /login_submit.cgi with different usernames in txtUsrName parameter; analyze if response messages differ between existing and non-existing accountsCheck Version:
Check VPN appliance web interface or CLI for firmware version; consult H3C documentationVerify Fix Applied:
Test that identical responses are returned for both valid and invalid usernames; no discernible difference in timing or content📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts with different usernames from same source IP
- Unusual patterns of requests to login_submit.cgi
Network Indicators:
- HTTP POST requests to /login_submit.cgi with varying txtUsrName values
- High volume of login attempts
SIEM Query:
source_ip=* AND uri_path="/login_submit.cgi" AND http_method="POST" | stats count by source_ip, form_data.txtUsrName