CVE-2023-27362
📋 TL;DR
This vulnerability allows local attackers to escalate privileges on 3CX installations by exploiting an insecure OpenSSL configuration file location. Attackers with initial low-privileged access can execute arbitrary code as SYSTEM. Affects 3CX users with vulnerable versions installed.
💻 Affected Systems
- 3CX Phone System
📦 What is this software?
3cx by 3cx
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with SYSTEM privileges, enabling installation of persistent malware, credential theft, and lateral movement across the network.
Likely Case
Local privilege escalation leading to data exfiltration, persistence establishment, and further exploitation of the compromised system.
If Mitigated
Limited to initial access vector impact if proper endpoint security controls and least privilege principles are enforced.
🎯 Exploit Status
Requires local access and ability to execute low-privileged code first. The vulnerability is well-documented and relatively straightforward to exploit once initial access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3CX v18 Update 8
Vendor Advisory: https://www.3cx.com/blog/releases/v18-u8/
Restart Required: Yes
Instructions:
1. Backup current 3CX configuration. 2. Download and install 3CX v18 Update 8 from the 3CX website. 3. Restart the 3CX services or the entire system as prompted. 4. Verify the update completed successfully.
🔧 Temporary Workarounds
Restrict Write Access to OpenSSL Config Directory
windowsRemove write permissions for non-administrative users to the directory where OpenSSL configuration files are loaded from.
icacls "C:\Program Files\3CX Phone System\Bin\" /deny Users:(OI)(CI)W
Implement Least Privilege
windowsEnsure 3CX services run with minimal necessary privileges and users have limited local access rights.
🧯 If You Can't Patch
- Implement strict endpoint security controls to prevent initial low-privileged code execution
- Monitor for suspicious privilege escalation attempts and file modifications in 3CX directories
🔍 How to Verify
Check if Vulnerable:
Check 3CX version in the Management Console under Dashboard > System Information. If version is below v18 Update 8, the system is vulnerable.Check Version:
In 3CX Management Console: Dashboard > System Information > VersionVerify Fix Applied:
Confirm version shows v18 Update 8 or higher in System Information. Verify OpenSSL configuration file permissions are properly restricted.📡 Detection & Monitoring
Log Indicators:
- Unusual process creation from 3CX directories with SYSTEM privileges
- Modifications to OpenSSL configuration files in 3CX directories
- Failed privilege escalation attempts in Windows Event Logs
Network Indicators:
- Unusual outbound connections from 3CX services
- Lateral movement attempts from 3CX server
SIEM Query:
EventID=4688 AND (NewProcessName:*\3CX* OR ParentProcessName:*\3CX*) AND SubjectUserName!=SYSTEM