CVE-2021-33534

Q: What is the severity of CVE-2021-33534?

CVE-2021-33534 has a CVSS score of 7.2 (HIGH). This vulnerability allows authenticated high-privilege attackers to execute arbitrary system commands on Weidmueller Industrial WLAN devices by injecting malicious commands into the hostname configuration field. Successful exploitation gives attackers full control of affected devices. Industrial organizations using these specific WLAN devices are affected.

7.2 HIGH

Remote Code Execution

📋 TL;DR

This vulnerability allows authenticated high-privilege attackers to execute arbitrary system commands on Weidmueller Industrial WLAN devices by injecting malicious commands into the hostname configuration field. Successful exploitation gives attackers full control of affected devices. Industrial organizations using these specific WLAN devices are affected.

💻 Affected Systems

Products:

Weidmueller Industrial WLAN devices

Versions: Multiple versions (specific versions not detailed in provided references)

Operating Systems: Embedded OS on Weidmueller devices

Default Config Vulnerable: ⚠️ Yes

Notes: Requires authenticated access with high privileges. All devices with vulnerable firmware versions are affected.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete device compromise allowing attackers to disrupt industrial operations, steal sensitive data, or pivot to other network segments.

🟠

Likely Case

Attackers with valid high-privilege credentials gain persistent access to industrial network devices for espionage or disruption.

🟢

If Mitigated

Limited impact due to network segmentation, strong authentication controls, and monitoring preventing credential misuse.

🌐 Internet-Facing: MEDIUM - While exploitation requires authentication, exposed devices with default/weak credentials remain vulnerable.

🏢 Internal Only: HIGH - Industrial networks often have privileged users who could be compromised or malicious insiders.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: LOW

Exploitation requires valid high-privilege credentials but command injection is straightforward once authenticated.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Not specified in provided references - check vendor advisory

Vendor Advisory: https://cert.vde.com/en-us/advisories/vde-2021-026

Restart Required: Yes

Instructions:

1. Check current firmware version. 2. Download latest firmware from Weidmueller support portal. 3. Backup configuration. 4. Apply firmware update via web interface or console. 5. Verify update successful and reconfigure if needed.

🔧 Temporary Workarounds

Restrict network access

all

Limit device access to only necessary management networks and users

Strengthen authentication

all

Enforce strong passwords, multi-factor authentication, and regular credential rotation

🧯 If You Can't Patch

Implement strict network segmentation to isolate industrial WLAN devices from general network
Deploy intrusion detection systems monitoring for command injection patterns in network traffic

🔍 How to Verify

Check if Vulnerable:

Check device firmware version against vendor advisory. Attempt to inject test commands in hostname field (only in test environment).

Check Version:

Check via web interface: System > About or via CLI: show version

Verify Fix Applied:

Verify firmware version is updated to patched version. Test command injection in hostname field should no longer execute.

📡 Detection & Monitoring

Log Indicators:

Unusual command execution in system logs
Multiple failed authentication attempts followed by successful login
Changes to hostname configuration with suspicious characters

Network Indicators:

Unusual outbound connections from industrial WLAN devices
Command injection patterns in HTTP POST requests to configuration endpoints

SIEM Query:

source="industrial_wlan" AND (event_type="config_change" AND field="hostname" AND value MATCH "[;|&`]" OR event_type="command_exec" AND user!="authorized_user")

📊 Metadata

CVE ID: CVE-2021-33534

CVSS v3 Score: 7.2 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-78

Published: June 25, 2021

Last Updated: November 21, 2024

🔗 References

https://cert.vde.com/en-us/advisories/vde-2021-026 Third Party Advisory
https://cert.vde.com/en-us/advisories/vde-2021-026 Third Party Advisory