CVE-2020-14030
📋 TL;DR
This vulnerability in Ozeki NG SMS Gateway allows attackers to achieve remote code execution by exploiting insecure .NET deserialization. Attackers can write malicious serialized files to the filesystem that the application will deserialize, executing arbitrary code. All users of Ozeki NG SMS Gateway through version 4.17.6 are affected.
💻 Affected Systems
- Ozeki NG SMS Gateway
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control over the server, allowing data theft, lateral movement, and persistent backdoor installation.
Likely Case
Attacker gains remote code execution with application-level privileges, potentially leading to SMS interception, data exfiltration, and further network compromise.
If Mitigated
With proper network segmentation and least privilege, impact limited to the SMS gateway application and its data.
🎯 Exploit Status
Exploit requires ability to write files to the SMS storage directory, which may be accessible via various attack vectors.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.17.7 or later
Vendor Advisory: http://www.ozeki.hu/index.php?owpn=231
Restart Required: Yes
Instructions:
1. Download latest version from Ozeki website. 2. Backup configuration and data. 3. Install update. 4. Restart service. 5. Verify functionality.
🔧 Temporary Workarounds
Restrict filesystem access
windowsApply strict filesystem permissions to SMS storage directory to prevent unauthorized file writes.
icacls "C:\Program Files\Ozeki\OzekiNG SMS Gateway\Data" /deny Everyone:(W)
Network segmentation
allIsolate SMS gateway from internet and restrict access to necessary network segments only.
🧯 If You Can't Patch
- Implement strict filesystem permissions on SMS storage directory to prevent unauthorized writes
- Deploy application-level firewall rules to restrict access to SMS gateway service
🔍 How to Verify
Check if Vulnerable:
Check installed version in application interface or registry: HKEY_LOCAL_MACHINE\SOFTWARE\Ozeki\OzekiNG SMS Gateway\VersionCheck Version:
reg query "HKEY_LOCAL_MACHINE\SOFTWARE\Ozeki\OzekiNG SMS Gateway" /v VersionVerify Fix Applied:
Verify version is 4.17.7 or later and test SMS functionality remains operational.📡 Detection & Monitoring
Log Indicators:
- Unusual file writes to SMS storage directory
- Failed deserialization attempts in application logs
- Unexpected process execution from SMS gateway context
Network Indicators:
- Unusual outbound connections from SMS gateway server
- SMS traffic anomalies
SIEM Query:
source="OzekiSMS" AND (event_type="deserialization_error" OR process_execution="powershell" OR process_execution="cmd")🔗 References
- http://www.ozeki.hu/index.php?owpn=231
- https://github.com/DrunkenShells/Disclosures/tree/master/CVE-2020-14030-RCE%20via%20.NET%20Deserialization-Ozeki%20SMS%20Gateway
- http://www.ozeki.hu/index.php?owpn=231
- https://github.com/DrunkenShells/Disclosures/tree/master/CVE-2020-14030-RCE%20via%20.NET%20Deserialization-Ozeki%20SMS%20Gateway
