CVE-2025-34254
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to enumerate valid usernames on D-Link Nuclias Connect systems by observing different error messages in login responses. Attackers can determine which accounts exist on the server, facilitating targeted credential attacks. All systems running affected firmware versions are vulnerable.
💻 Affected Systems
- D-Link Nuclias Connect
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers build a complete list of valid usernames, then conduct targeted password attacks leading to unauthorized access and potential system compromise.
Likely Case
Attackers enumerate some valid usernames and use them for credential stuffing or targeted phishing campaigns.
If Mitigated
Attackers can still enumerate usernames but cannot gain access due to strong passwords and multi-factor authentication.
🎯 Exploit Status
Exploitation requires only HTTP requests to the login endpoint and observation of response differences.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not yet released
Vendor Advisory: https://supportannouncement.us.dlink.com/security/publication.aspx?name=SAP10472
Restart Required: No
Instructions:
Monitor D-Link security advisories for patch release. Apply firmware update when available through Nuclias Connect web interface.
🔧 Temporary Workarounds
Network Access Control
allRestrict access to Nuclias Connect management interface to trusted IP addresses only
Web Application Firewall
allConfigure WAF to normalize login error responses or block enumeration patterns
🧯 If You Can't Patch
- Implement network segmentation to isolate Nuclias Connect from untrusted networks
- Enable multi-factor authentication and enforce strong password policies
🔍 How to Verify
Check if Vulnerable:
Send POST requests to /login endpoint with valid and invalid usernames, compare error.message values in JSON responsesCheck Version:
Check firmware version in Nuclias Connect web interface under System > AboutVerify Fix Applied:
After patching, test that login responses return identical error messages regardless of username validity📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts with different usernames from same source
- Unusual pattern of login requests testing various usernames
Network Indicators:
- High volume of POST requests to /login endpoint
- Requests with systematically varied username parameters
SIEM Query:
source_ip='*' AND destination_port=443 AND url_path='/login' AND http_method='POST' | stats count by source_ip, username | where count > threshold