CVE-2019-5138
📋 TL;DR
CVE-2019-5138 is a critical command injection vulnerability in Moxa AWK-3131A wireless access points that allows authenticated low-privilege users to execute arbitrary commands via specially crafted diagnostic scripts. This vulnerability enables remote attackers to gain full control over affected devices running firmware version 1.13. Organizations using these industrial networking devices are at risk of complete device compromise.
💻 Affected Systems
- Moxa AWK-3131A
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device takeover allowing attackers to install persistent backdoors, pivot to internal networks, disrupt industrial operations, or use the device as a foothold for further attacks.
Likely Case
Remote code execution leading to device compromise, data exfiltration, network reconnaissance, and potential lateral movement within industrial control systems.
If Mitigated
Limited impact if proper network segmentation, authentication controls, and monitoring are in place to detect and block exploitation attempts.
🎯 Exploit Status
Exploitation requires authentication but only low-privilege credentials. Public exploit code exists and has been weaponized in attack frameworks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware version 1.14 or later
Vendor Advisory: https://www.moxa.com/en/support/product-support/security-advisory/moxa-awk-3131a-series-wireless-ap-bridge-client-access-points-vulnerabilities
Restart Required: Yes
Instructions:
1. Download firmware version 1.14 or later from Moxa support portal. 2. Backup current configuration. 3. Upload new firmware via web interface. 4. Reboot device. 5. Restore configuration if needed.
🔧 Temporary Workarounds
Disable diagnostic script functionality
allRemove or restrict access to diagnostic script upload feature if not required for operations.
Network segmentation
allIsolate AWK-3131A devices in separate VLANs with strict firewall rules limiting access to management interfaces.
🧯 If You Can't Patch
- Implement strict access controls allowing only trusted administrators to access device management interfaces
- Deploy network monitoring and intrusion detection systems to detect exploitation attempts and command injection patterns
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface (System Maintenance > Firmware) or CLI command 'show version'. If version is 1.13, device is vulnerable.Check Version:
show versionVerify Fix Applied:
Verify firmware version is 1.14 or later. Test diagnostic script upload functionality to ensure command injection is no longer possible.📡 Detection & Monitoring
Log Indicators:
- Unusual diagnostic script uploads
- BusyBox command execution from web interface
- Multiple failed authentication attempts followed by successful login and script upload
Network Indicators:
- HTTP POST requests to diagnostic script upload endpoints with suspicious payloads
- Outbound connections from device to unexpected destinations
SIEM Query:
source="awk-3131a" AND (event="diagnostic_upload" OR event="command_execution")