CVE-2021-47705
📋 TL;DR
CVE-2021-47705 is a heap-based buffer overflow vulnerability in COMMAX UMS Client ActiveX Control's CNC_Ctrl.dll that allows remote code execution. Attackers can exploit improper boundary validation by providing excessively long string arrays through multiple functions. Organizations using COMMAX UMS Client 1.7.0.2 with ActiveX enabled are affected.
💻 Affected Systems
- COMMAX UMS Client
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining SYSTEM-level privileges, enabling complete control of the affected system, data theft, and lateral movement within the network.
Likely Case
Remote code execution with the privileges of the user running the ActiveX control, potentially leading to malware installation, data exfiltration, or system disruption.
If Mitigated
Denial of service or application crash if exploit attempts are blocked by security controls, but no code execution.
🎯 Exploit Status
Exploit code is publicly available on Exploit-DB (ID 50232), making exploitation straightforward for attackers with basic skills.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.commax.com
Restart Required: No
Instructions:
1. Check COMMAX website for security updates. 2. If patch exists, download and install. 3. Restart affected systems if required by patch.
🔧 Temporary Workarounds
Disable ActiveX Control
windowsPrevent the vulnerable ActiveX control from loading in Internet Explorer or other applications.
reg add "HKLM\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{CLSID}" /v "Compatibility Flags" /t REG_DWORD /d 0x400 /f
Block CNC_Ctrl.dll Execution
windowsUse application control or antivirus to block execution of the vulnerable DLL.
🧯 If You Can't Patch
- Network segmentation to isolate systems running COMMAX UMS Client
- Implement strict application whitelisting to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check if CNC_Ctrl.dll version 1.7.0.2 exists on system and if ActiveX is enabled for COMMAX UMS Client.Check Version:
wmic datafile where name="C:\\Path\\To\\CNC_Ctrl.dll" get versionVerify Fix Applied:
Verify CNC_Ctrl.dll version is updated or removed, and ActiveX control is disabled.📡 Detection & Monitoring
Log Indicators:
- Process creation events for unexpected executables
- Application crashes of COMMAX UMS Client
Network Indicators:
- Unusual outbound connections from systems running COMMAX UMS Client
SIEM Query:
EventID=4688 AND (ProcessName="cmd.exe" OR ProcessName="powershell.exe") AND ParentProcessName contains "COMMAX"