CVE-2021-42106
📋 TL;DR
This vulnerability allows a local attacker with low-privileged code execution on affected Trend Micro security products to escalate privileges to higher system levels. It affects Trend Micro Apex One, Apex One as a Service, Worry-Free Business Security 10.0 SP1, and Worry-Free Business Security Services. Attackers must already have some access to the system to exploit this privilege escalation flaw.
💻 Affected Systems
- Trend Micro Apex One
- Trend Micro Apex One as a Service
- Trend Micro Worry-Free Business Security 10.0 SP1
- Trend Micro Worry-Free Business Security Services
📦 What is this software?
Apex One by Trendmicro
Apex One by Trendmicro
⚠️ Risk & Real-World Impact
Worst Case
An attacker gains full administrative control over the system, potentially compromising the entire endpoint security infrastructure and enabling further lateral movement.
Likely Case
Local attackers elevate from limited user privileges to system-level access, allowing them to disable security controls, install malware, or access sensitive data.
If Mitigated
With proper access controls and monitoring, exploitation attempts are detected and contained before significant damage occurs.
🎯 Exploit Status
Exploitation requires existing low-privileged code execution on the target system. The vulnerability involves improper privilege management (CWE-269).
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check specific product updates via Trend Micro advisories
Vendor Advisory: https://success.trendmicro.com/solution/000289229
Restart Required: Yes
Instructions:
1. Review Trend Micro advisories for specific patch versions. 2. Apply the latest security updates through the product's update mechanism. 3. Restart affected systems to complete installation. 4. Verify successful update through version checks.
🔧 Temporary Workarounds
Restrict local access
windowsLimit user accounts with local login privileges to reduce attack surface
Implement least privilege
windowsEnsure all user accounts operate with minimum necessary privileges
🧯 If You Can't Patch
- Implement strict access controls to prevent unauthorized local access to affected systems
- Deploy endpoint detection and response (EDR) solutions to monitor for privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check Trend Micro product version against vendor advisories at https://success.trendmicro.com/solution/000289229Check Version:
Check through Trend Micro product console or Windows Programs and FeaturesVerify Fix Applied:
Verify product version matches or exceeds the patched version specified in Trend Micro advisories📡 Detection & Monitoring
Log Indicators:
- Unusual privilege escalation events in Windows Security logs
- Suspicious process creation with elevated privileges
- Trend Micro service manipulation attempts
Network Indicators:
- Not applicable - local exploitation only
SIEM Query:
EventID=4672 OR EventID=4688 with suspicious parent processes and privilege changes🔗 References
- https://success.trendmicro.com/solution/000289229
- https://success.trendmicro.com/solution/000289230
- https://www.zerodayinitiative.com/advisories/ZDI-21-1218/
- https://success.trendmicro.com/solution/000289229
- https://success.trendmicro.com/solution/000289230
- https://www.zerodayinitiative.com/advisories/ZDI-21-1218/
