CVE-2021-25247
📋 TL;DR
A DLL hijacking vulnerability in Trend Micro HouseCall for Home Networks allows local attackers to escalate privileges and execute arbitrary code by placing a malicious DLL in a location the application searches. This affects users with local access to systems running vulnerable versions. Attackers need existing user privileges to exploit this vulnerability.
💻 Affected Systems
- Trend Micro HouseCall for Home Networks
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with administrative privileges, allowing installation of persistent malware, data theft, and lateral movement.
Likely Case
Local privilege escalation leading to unauthorized administrative access on the affected machine.
If Mitigated
Limited impact due to proper access controls preventing local user access or DLL execution restrictions.
🎯 Exploit Status
Requires local user privileges and ability to place DLL in specific directory. DLL hijacking is a well-known technique.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.3.1064 or later
Vendor Advisory: https://helpcenter.trendmicro.com/en-us/article/TMKA-10180
Restart Required: Yes
Instructions:
1. Download latest version from Trend Micro website. 2. Run installer to update. 3. Restart system to ensure changes take effect.
🔧 Temporary Workarounds
Restrict DLL loading from untrusted directories
windowsUse Windows policies to restrict DLL loading from user-writable directories
Configure Windows AppLocker or Software Restriction Policies
Remove unnecessary user privileges
windowsLimit local user permissions to prevent DLL placement in application directories
Use Windows Group Policy to restrict write access to program directories
🧯 If You Can't Patch
- Uninstall Trend Micro HouseCall for Home Networks if not required
- Implement strict access controls to prevent local users from writing to application directories
🔍 How to Verify
Check if Vulnerable:
Check Help > About in HouseCall application for version number. If version is 5.3.1063 or below, system is vulnerable.Check Version:
Not applicable - check via application GUIVerify Fix Applied:
Verify version is 5.3.1064 or higher in Help > About menu.📡 Detection & Monitoring
Log Indicators:
- Windows Event Logs showing DLL loading from unusual locations
- Process creation events from HouseCall with unexpected parent processes
Network Indicators:
- Unusual outbound connections from HouseCall process
SIEM Query:
Process creation where (parent_process contains 'housecall' OR image contains 'housecall') AND command_line contains '.dll'