CVE-2021-42012
📋 TL;DR
A stack-based buffer overflow vulnerability in Trend Micro Apex One and Worry-Free Business Security allows a local attacker with low-privileged code execution to escalate privileges on affected systems. This affects on-premises and cloud-based installations. Attackers must first gain initial access to exploit this vulnerability.
💻 Affected Systems
- Trend Micro Apex One
- Trend Micro Apex One as a Service
- Trend Micro Worry-Free Business Security
📦 What is this software?
Apex One by Trendmicro
Apex One by Trendmicro
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with administrative privileges, enabling persistence, lateral movement, and data exfiltration.
Likely Case
Local privilege escalation from a standard user to SYSTEM/root level access on the compromised endpoint.
If Mitigated
Limited impact if proper endpoint security controls prevent initial low-privileged code execution.
🎯 Exploit Status
Exploit requires local access and low-privileged code execution first. ZDI published technical details and proof-of-concept.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apex One 2019 Build 11180 or later, Worry-Free Business Security 10.0 SP1 Patch 1
Vendor Advisory: https://success.trendmicro.com/solution/000289229
Restart Required: Yes
Instructions:
1. Download the latest hotfix from Trend Micro support portal. 2. Apply the patch to all affected endpoints. 3. Restart systems to complete installation. 4. Verify patch installation through management console.
🔧 Temporary Workarounds
Restrict local user privileges
windowsLimit standard user accounts to prevent initial low-privileged code execution required for exploitation.
Use Group Policy to restrict standard user permissions
Implement least privilege access controls
🧯 If You Can't Patch
- Implement strict endpoint security controls to prevent initial low-privileged code execution
- Isolate affected systems from critical network segments and monitor for privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check Trend Micro agent version in Control Manager or locally via 'About' in agent interface.Check Version:
Check agent version in Trend Micro Control Manager or via local agent interfaceVerify Fix Applied:
Verify agent version is Apex One 2019 Build 11180+ or Worry-Free 10.0 SP1 Patch 1+ in management console.📡 Detection & Monitoring
Log Indicators:
- Unusual privilege escalation events in Windows Security logs
- Trend Micro agent crash or unexpected behavior logs
Network Indicators:
- Unusual outbound connections from Trend Micro agent processes post-exploitation
SIEM Query:
EventID=4688 AND ProcessName LIKE '%tmccsf.exe%' AND NewProcessName='cmd.exe' OR ParentProcessName LIKE '%tmccsf.exe%'🔗 References
- https://success.trendmicro.com/solution/000289229
- https://success.trendmicro.com/solution/000289230
- https://www.zerodayinitiative.com/advisories/ZDI-21-1221/
- https://success.trendmicro.com/solution/000289229
- https://success.trendmicro.com/solution/000289230
- https://www.zerodayinitiative.com/advisories/ZDI-21-1221/
