CVE-2021-28817
📋 TL;DR
This vulnerability allows a low-privileged attacker with local Windows access to insert malicious software into TIBCO Rendezvous installation directories. The software then executes with elevated privileges due to improper file/folder permissions. Affected users are those running vulnerable versions of TIBCO Rendezvous or TIBCO Rendezvous Developer Edition on Windows systems.
💻 Affected Systems
- TIBCO Rendezvous
- TIBCO Rendezvous Developer Edition
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise via privilege escalation to SYSTEM/administrator level, enabling complete control over the affected Windows host.
Likely Case
Local privilege escalation allowing attackers to install persistent malware, steal credentials, or pivot to other systems.
If Mitigated
Limited impact with proper access controls and monitoring preventing malicious file placement.
🎯 Exploit Status
Exploitation requires local access and ability to write files to installation directories. No authentication bypass needed beyond initial low-privilege access.
🛠️ 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 updated version from TIBCO support portal. 2. Uninstall vulnerable version. 3. Install patched version. 4. Restart system.
🔧 Temporary Workarounds
Restrict installation directory permissions
windowsRemove write permissions for low-privileged users on TIBCO Rendezvous installation directories
icacls "C:\Program Files\TIBCO\Rendezvous\*" /deny Users:(OI)(CI)W
icacls "C:\Program Files (x86)\TIBCO\Rendezvous\*" /deny Users:(OI)(CI)W
🧯 If You Can't Patch
- Implement strict access controls on installation directories to prevent low-privileged users from writing files
- Monitor for unauthorized file creation in TIBCO installation directories using file integrity monitoring
🔍 How to Verify
Check if Vulnerable:
Check TIBCO Rendezvous version via Control Panel > Programs and Features or registry: HKEY_LOCAL_MACHINE\SOFTWARE\TIBCO\Rendezvous\VersionCheck Version:
reg query "HKLM\SOFTWARE\TIBCO\Rendezvous" /v VersionVerify Fix Applied:
Verify version is above 8.5.1 and check installation directory permissions show no write access for low-privileged users📡 Detection & Monitoring
Log Indicators:
- Windows Event Logs showing file creation/modification in TIBCO installation directories by low-privileged users
- Process execution from TIBCO directories with unexpected parent processes
Network Indicators:
- Unusual outbound connections from TIBCO Rendezvous processes
SIEM Query:
source="Windows Security" EventCode=4663 ObjectName="*TIBCO*Rendezvous*" AccessMask="0x2"