CVE-2019-12769
📋 TL;DR
This CVE describes a Cross-Site Request Forgery (CSRF) vulnerability in SolarWinds Serv-U Managed File Transfer Web client that allows attackers to trick authenticated users into uploading arbitrary files to the server. The vulnerability affects users of SolarWinds Serv-U MFT Web client before version 15.1.6 Hotfix 2. Attackers can exploit this by crafting malicious web pages that trigger unauthorized file uploads when visited by authenticated users.
💻 Affected Systems
- SolarWinds Serv-U Managed File Transfer Web client
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could upload malicious files (webshells, malware) to the server, potentially leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Unauthorized file uploads leading to data exfiltration, malware distribution, or website defacement through uploaded content.
If Mitigated
Limited impact with proper CSRF protections, file upload restrictions, and network segmentation in place.
🎯 Exploit Status
Exploitation requires the victim to be authenticated and visit a malicious page. The vulnerability is well-documented with public proof-of-concept available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 15.1.6 Hotfix 2
Vendor Advisory: https://support.solarwinds.com/SuccessCenter/s/article/Serv-U-15-1-6-HotFix-2
Restart Required: Yes
Instructions:
1. Download SolarWinds Serv-U 15.1.6 Hotfix 2 from SolarWinds support portal. 2. Backup current configuration and data. 3. Stop Serv-U service. 4. Install the hotfix. 5. Restart Serv-U service. 6. Verify functionality.
🔧 Temporary Workarounds
Implement CSRF Tokens
allAdd CSRF protection tokens to file upload forms to validate legitimate requests
Restrict File Upload Types
allConfigure Serv-U to only allow specific file types and extensions for upload
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to block malicious upload requests
- Restrict access to Serv-U web interface to trusted networks only
🔍 How to Verify
Check if Vulnerable:
Check Serv-U version in web interface admin panel or via system informationCheck Version:
Check Serv-U admin console → Help → About or system information pageVerify Fix Applied:
Verify version shows 15.1.6 Hotfix 2 or later in admin interface📡 Detection & Monitoring
Log Indicators:
- Unusual file upload patterns
- Multiple failed upload attempts from same IP
- Uploads to unusual directories
Network Indicators:
- HTTP POST requests to upload endpoint with suspicious parameters
- Requests containing ?Command=Upload with unusual Dir/File parameters
SIEM Query:
source="serv-u.log" AND ("Command=Upload" OR "file upload") AND status=200🔗 References
- https://medium.com/%40clod81/cve-2019-12769-solarwinds-serv-u-managed-file-transfer-mft-web-client-15-1-6-a2dab98d668d
- https://support.solarwinds.com/SuccessCenter/s/article/Serv-U-15-1-6-HotFix-2
- https://medium.com/%40clod81/cve-2019-12769-solarwinds-serv-u-managed-file-transfer-mft-web-client-15-1-6-a2dab98d668d
- https://support.solarwinds.com/SuccessCenter/s/article/Serv-U-15-1-6-HotFix-2
