CVE-2021-28821
📋 TL;DR
This vulnerability allows a low-privileged attacker with local Windows access to insert malicious files into TIBCO Enterprise Message Service installations. The service then executes these files with elevated privileges due to insufficient file/folder access restrictions. Affected are all TIBCO Enterprise Message Service editions (Standard, Community, Developer) versions 8.5.1 and below on Windows systems.
💻 Affected Systems
- TIBCO Enterprise Message Service
- TIBCO Enterprise Message Service - Community Edition
- TIBCO Enterprise Message Service - Developer Edition
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise via privilege escalation to SYSTEM/Administrator level, enabling installation of persistent malware, data theft, or lateral movement across the network.
Likely Case
Local privilege escalation allowing attackers to gain administrative control over the affected Windows system and potentially pivot to other systems.
If Mitigated
Limited impact if proper access controls and privilege separation are implemented, though local attackers could still potentially exploit the vulnerability.
🎯 Exploit Status
Exploitation requires local access but is theoretically straightforward once an attacker can write files to the vulnerable directories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions above 8.5.1
Vendor Advisory: http://www.tibco.com/services/support/advisories
Restart Required: Yes
Instructions:
1. Download the latest version from TIBCO's official website. 2. Backup configuration files. 3. Uninstall the vulnerable version. 4. Install the patched version. 5. Restore configurations. 6. Restart the service.
🔧 Temporary Workarounds
Restrict File Permissions
windowsApply strict access controls to TIBCO EMS installation directories to prevent low-privileged users from writing files.
icacls "C:\Program Files\TIBCO\ems\" /inheritance:r /grant:r "SYSTEM:(OI)(CI)F" "Administrators:(OI)(CI)F" /deny "Users:(OI)(CI)W"
icacls "C:\Program Files (x86)\TIBCO\ems\" /inheritance:r /grant:r "SYSTEM:(OI)(CI)F" "Administrators:(OI)(CI)F" /deny "Users:(OI)(CI)W"
Run Service with Least Privilege
windowsConfigure the TIBCO EMS service to run with minimal necessary privileges rather than elevated system privileges.
sc config "TIBCO EMS" obj= "NT AUTHORITY\LocalService"
sc config "TIBCO EMS" type= own
🧯 If You Can't Patch
- Implement strict network segmentation to isolate affected systems from critical assets.
- Deploy endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts and file writes to TIBCO directories.
🔍 How to Verify
Check if Vulnerable:
Check the installed version of TIBCO EMS via Control Panel > Programs and Features or by examining the installation directory for version information.Check Version:
wmic product where "name like 'TIBCO Enterprise Message Service%'" get versionVerify Fix Applied:
Verify the installed version is above 8.5.1 and check that file permissions on installation directories restrict write access to non-administrative users.📡 Detection & Monitoring
Log Indicators:
- Unexpected file writes to TIBCO EMS installation directories
- Privilege escalation events in Windows Security logs
- Service execution of unexpected binaries
Network Indicators:
- Unusual outbound connections from TIBCO EMS service
- Lateral movement attempts from the affected system
SIEM Query:
EventID=4688 AND (NewProcessName:*\ems\* OR CommandLine:*\ems\*) | where SubjectUserName != "SYSTEM" AND SubjectUserName != "Administrator"