CVE-2021-42108
📋 TL;DR
This vulnerability allows a local attacker with low-privileged code execution on affected Trend Micro security products to escalate privileges via the Web Console. It affects Trend Micro Apex One, Apex One as a Service, and Worry-Free Business Security 10.0 SP1 installations. Attackers must already have some foothold on 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
📦 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 security product, potentially disabling protection, exfiltrating sensitive data, or using the compromised system as a pivot point for further network attacks.
Likely Case
Local attackers escalate from limited user privileges to administrator-level access within the Trend Micro console, allowing them to modify security settings, bypass protections, or access protected logs and configurations.
If Mitigated
With proper access controls and network segmentation, the impact is limited to the local system where the attacker already has some foothold, preventing lateral movement or broader network compromise.
🎯 Exploit Status
Exploitation requires local access and initial code execution. The vulnerability is in the Web Console's privilege management.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply the latest security patch from Trend Micro
Vendor Advisory: https://success.trendmicro.com/solution/000289229
Restart Required: Yes
Instructions:
1. Log into the Trend Micro console. 2. Navigate to the update section. 3. Apply the latest security patch. 4. Restart the affected services or system as required.
🔧 Temporary Workarounds
Restrict Local Access
windowsLimit local user access to systems running affected Trend Micro products to only trusted administrators.
Network Segmentation
allIsolate systems running the Trend Web Console from general user networks to reduce attack surface.
🧯 If You Can't Patch
- Implement strict least-privilege access controls on all systems running affected Trend Micro products
- Monitor for unusual privilege escalation attempts and console access patterns
🔍 How to Verify
Check if Vulnerable:
Check the Trend Micro product version against affected versions listed in the vendor advisory.Check Version:
Check within the Trend Micro console under About or System InformationVerify Fix Applied:
Verify that the latest security patch has been applied and the product version is no longer in the vulnerable range.📡 Detection & Monitoring
Log Indicators:
- Unusual privilege escalation attempts in Trend Micro logs
- Multiple failed then successful authentication attempts to Web Console
- Unexpected changes to security policy or configuration
Network Indicators:
- Unusual outbound connections from Trend Micro management systems
- Traffic patterns suggesting lateral movement from compromised security consoles
SIEM Query:
source="trend_micro" AND (event_type="privilege_escalation" OR user="*" AND action="admin_access")🔗 References
- https://success.trendmicro.com/solution/000289229
- https://success.trendmicro.com/solution/000289230
- https://www.zerodayinitiative.com/advisories/ZDI-21-1217/
- https://success.trendmicro.com/solution/000289229
- https://success.trendmicro.com/solution/000289230
- https://www.zerodayinitiative.com/advisories/ZDI-21-1217/
