CVE-2021-28023
📋 TL;DR
This vulnerability allows authenticated attackers to upload malicious ZIP files containing JSP code through ServiceTonic's Service import feature. When extracted, the files can be placed in relative paths leading to remote code execution. All ServiceTonic Helpdesk installations before version 9.0.35937 are affected.
💻 Affected Systems
- ServiceTonic Helpdesk
📦 What is this software?
Servicetonic by Servicetonic
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining complete control over the server, accessing sensitive data, and using the system as a foothold for lateral movement.
Likely Case
Remote code execution leading to data theft, service disruption, and potential ransomware deployment.
If Mitigated
Attack blocked at perimeter with file upload restrictions, resulting in failed exploitation attempts.
🎯 Exploit Status
Exploitation requires authentication but is straightforward once access is obtained. The vulnerability was chained with other exploits in documented attacks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 9.0.35937 and later
Vendor Advisory: https://www.servicetonic.com/
Restart Required: Yes
Instructions:
1. Backup your ServiceTonic installation and database. 2. Download the latest version from the vendor portal. 3. Follow the vendor's upgrade documentation. 4. Restart the application server. 5. Verify the version is 9.0.35937 or higher.
🔧 Temporary Workarounds
Disable Service Import Feature
allTemporarily disable the vulnerable Service import functionality until patching is complete.
Consult ServiceTonic documentation for disabling specific modules or features
Implement File Upload Restrictions
linuxConfigure web application firewall or reverse proxy to block ZIP file uploads to the Service import endpoint.
# Example nginx location block
location /servicetonic/import {
deny all;
}
🧯 If You Can't Patch
- Implement strict network segmentation to isolate ServiceTonic servers from critical systems
- Enable detailed logging and monitoring for file upload activities and unusual process execution
🔍 How to Verify
Check if Vulnerable:
Check the ServiceTonic version in the admin interface or application files. If version is below 9.0.35937, the system is vulnerable.Check Version:
Check the admin dashboard or look for version information in the application's configuration files.Verify Fix Applied:
Confirm the version is 9.0.35937 or higher and test that ZIP file uploads in the Service import feature are properly validated.📡 Detection & Monitoring
Log Indicators:
- Unusual ZIP file uploads to Service import endpoints
- JSP file creation in unexpected directories
- Unusual process execution from web application context
Network Indicators:
- HTTP POST requests with ZIP files to /servicetonic/import endpoints
- Outbound connections from ServiceTonic server to unknown IPs
SIEM Query:
source="servicetonic" AND (uri_path="/import" AND file_type="zip") OR (process_name="java" AND cmdline="*jsp*")