CVE-2023-54337
📋 TL;DR
Sysax Multi Server 6.95 contains a denial of service vulnerability where attackers can crash the application by sending 800 bytes of repeated characters to the administrative password field. This affects all users running the vulnerable version of Sysax Multi Server, potentially disrupting server functionality.
💻 Affected Systems
- Sysax Multi Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete service disruption making the Sysax Multi Server unavailable, potentially affecting all services running through it including FTP, SSH, and web services.
Likely Case
Application crash requiring manual restart, causing temporary service interruption until the server is restored.
If Mitigated
Minimal impact if proper network segmentation and access controls prevent unauthorized access to administrative interfaces.
🎯 Exploit Status
Exploit code is publicly available and requires no authentication. Attackers only need network access to the administrative interface.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown - Check vendor for updates
Vendor Advisory: https://www.sysax.com/
Restart Required: Yes
Instructions:
1. Check Sysax website for security updates. 2. Download and install any available patches. 3. Restart the Sysax Multi Server service. 4. Verify the fix by testing with the exploit payload.
🔧 Temporary Workarounds
Restrict Administrative Interface Access
windowsBlock external access to the Sysax Multi Server administrative interface using firewall rules.
Windows Firewall: New-NetFirewallRule -DisplayName "Block Sysax Admin" -Direction Inbound -LocalPort [admin-port] -Protocol TCP -Action Block
Network Segmentation
allPlace Sysax Multi Server behind a firewall/VPN and restrict access to trusted IP addresses only.
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach the administrative interface
- Monitor for repeated connection attempts or crashes and implement automated restart scripts
🔍 How to Verify
Check if Vulnerable:
Test by sending 800 bytes of repeated characters (e.g., 'A' * 800) to the administrative password field via the web interface or API. If the server crashes, it's vulnerable.Check Version:
Check the Sysax Multi Server interface or installation directory for version information. Typically visible in the web interface or via Help > About.Verify Fix Applied:
After applying any vendor patch, repeat the test with the same payload. The server should handle the input gracefully without crashing.📡 Detection & Monitoring
Log Indicators:
- Application crash logs
- Unexpected service termination events
- Repeated failed login attempts with long password strings
Network Indicators:
- Unusually large authentication requests to administrative endpoints
- Multiple connection attempts followed by service unavailability
SIEM Query:
source="sysax.log" AND (event="crash" OR event="terminated") OR (http_request_length > 800 AND uri CONTAINS "/admin/")