CVE-2021-38420
📋 TL;DR
Delta Electronics DIALink versions 1.2.4.0 and earlier have insecure default permissions that grant excessive privileges to low-privileged user accounts. This allows attackers to modify the installation directory and upload malicious files, potentially leading to system compromise. Organizations using affected DIALink software are vulnerable.
💻 Affected Systems
- Delta Electronics DIALink
📦 What is this software?
Dialink by Deltaww
⚠️ Risk & Real-World Impact
Worst Case
An attacker gains full control of the system by uploading and executing malicious payloads, potentially compromising industrial control systems and causing operational disruption.
Likely Case
Attackers modify system files or upload malware to establish persistence, steal data, or pivot to other systems on the network.
If Mitigated
With proper access controls and monitoring, unauthorized modifications are detected and prevented before significant damage occurs.
🎯 Exploit Status
Exploitation requires low-privileged user access but is straightforward once obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.2.4.1 or later
Vendor Advisory: https://www.deltaww.com/en-US/Support/Downloads/Detail?code=DIALink
Restart Required: Yes
Instructions:
1. Download DIALink version 1.2.4.1 or later from Delta Electronics website. 2. Backup current configuration. 3. Run installer with administrative privileges. 4. Restart system after installation completes.
🔧 Temporary Workarounds
Restrict File Permissions
windowsManually adjust file system permissions to limit write access to DIALink installation directory.
icacls "C:\Program Files\Delta Electronics\DIALink" /deny Users:(OI)(CI)W
Implement Least Privilege
allRemove unnecessary user accounts and restrict remaining accounts to minimal required permissions.
🧯 If You Can't Patch
- Isolate DIALink systems on segmented network with strict firewall rules
- Implement file integrity monitoring on DIALink installation directory
🔍 How to Verify
Check if Vulnerable:
Check DIALink version in Help > About menu or examine installed programs list for versions 1.2.4.0 or earlier.Check Version:
Check Help > About in DIALink application or examine registry at HKEY_LOCAL_MACHINE\SOFTWARE\Delta Electronics\DIALinkVerify Fix Applied:
Confirm DIALink version is 1.2.4.1 or later and verify file permissions on installation directory restrict write access to non-admin users.📡 Detection & Monitoring
Log Indicators:
- Unexpected file modifications in DIALink directory
- Unauthorized user account activity
- Failed permission change attempts
Network Indicators:
- Unusual outbound connections from DIALink host
- Suspicious file transfers to/from DIALink system
SIEM Query:
EventID=4663 AND ObjectName LIKE '%DIALink%' AND Accesses LIKE '%WRITE%'