CVE-2021-25253
📋 TL;DR
This vulnerability allows a local attacker with low-privileged access to escalate privileges on Trend Micro Apex One and OfficeScan XG SP1 installations. It affects Trend Micro Apex One, Apex One as a Service, and OfficeScan XG SP1 products. Attackers must first gain initial access to the system before exploiting this improper access control flaw.
💻 Affected Systems
- Trend Micro Apex One
- Trend Micro Apex One as a Service
- Trend Micro OfficeScan XG SP1
📦 What is this software?
Apex One by Trendmicro
Apex One by Trendmicro
Officescan by Trendmicro
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with administrative privileges, enabling complete control over the endpoint, data exfiltration, and lateral movement within the network.
Likely Case
Local privilege escalation allowing attackers to bypass security controls, install malware, or access sensitive system resources.
If Mitigated
Limited impact if proper network segmentation, least privilege principles, and endpoint detection are implemented.
🎯 Exploit Status
Requires local access with low privileges. The vulnerability is in a service resource access control mechanism.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apex One 2019 (Build 11770) and later, OfficeScan XG SP1 Patch 4 (Build 6100) and later
Vendor Advisory: https://success.trendmicro.com/solution/000286019
Restart Required: Yes
Instructions:
1. Download the latest patch from Trend Micro support portal. 2. Apply the patch to all affected endpoints. 3. Restart the systems to complete installation. 4. Verify the patch is applied successfully.
🔧 Temporary Workarounds
Restrict local access
windowsLimit local user access to systems running affected Trend Micro products
Enhanced monitoring
allMonitor for privilege escalation attempts and unusual service activity
🧯 If You Can't Patch
- Implement strict network segmentation to isolate affected systems
- Apply principle of least privilege and monitor for suspicious local privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check the Trend Micro product version in the management console or client interfaceCheck Version:
Check via Trend Micro management console or client interface version informationVerify Fix Applied:
Verify the build number is at or above the patched versions: Apex One Build 11770+, OfficeScan XG SP1 Build 6100+📡 Detection & Monitoring
Log Indicators:
- Unusual service privilege changes
- Failed or successful privilege escalation attempts in system logs
- Trend Micro service access violations
Network Indicators:
- Unusual outbound connections from Trend Micro services
- Lateral movement attempts from affected systems
SIEM Query:
source="trendmicro" AND (event_type="privilege_escalation" OR service_access="unauthorized")🔗 References
- https://success.trendmicro.com/solution/000286019
- https://success.trendmicro.com/solution/000286157
- https://www.zerodayinitiative.com/advisories/ZDI-21-401/
- https://success.trendmicro.com/solution/000286019
- https://success.trendmicro.com/solution/000286157
- https://www.zerodayinitiative.com/advisories/ZDI-21-401/
