CVE-2021-33538
📋 TL;DR
This vulnerability in Weidmueller Industrial WLAN devices allows authenticated low-privilege users to overwrite other user account passwords by crafting a malicious username entry. Successful exploitation grants remote shell access as the compromised user, potentially leading to full device compromise. Organizations using affected Weidmueller Industrial WLAN devices are at risk.
💻 Affected Systems
- Weidmueller Industrial WLAN devices
📦 What is this software?
Ie Wl Vl Ap Br Cl Eu Firmware by Weidmueller
Ie Wl Vl Ap Br Cl Eu Firmware by Weidmueller
Ie Wl Vl Ap Br Cl Us Firmware by Weidmueller
Ie Wl Vl Ap Br Cl Us Firmware by Weidmueller
Ie Wlt Vl Ap Br Cl Eu Firmware by Weidmueller
Ie Wlt Vl Ap Br Cl Eu Firmware by Weidmueller
Ie Wlt Vl Ap Br Cl Us Firmware by Weidmueller
⚠️ Risk & Real-World Impact
Worst Case
Attacker gains administrative shell access, takes full control of industrial WLAN device, disrupts industrial operations, and uses device as pivot point into industrial control systems.
Likely Case
Attacker with low-privilege access escalates to higher privileges, modifies device configurations, intercepts network traffic, and potentially disrupts industrial communications.
If Mitigated
Attack fails due to proper network segmentation, strong authentication controls, and regular monitoring of user account changes.
🎯 Exploit Status
Exploitation requires authenticated access but is straightforward once authenticated. Industrial control system attackers likely have this capability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in provided references
Vendor Advisory: https://cert.vde.com/en-us/advisories/vde-2021-026
Restart Required: Yes
Instructions:
1. Contact Weidmueller support for latest firmware. 2. Backup device configuration. 3. Apply firmware update following vendor instructions. 4. Verify update applied successfully. 5. Restart device.
🔧 Temporary Workarounds
Restrict User Account Access
allLimit user accounts to only necessary personnel and implement strong password policies
Network Segmentation
allIsolate industrial WLAN devices from general corporate network and internet
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach the device management interface
- Enable detailed logging of all user account modifications and monitor for suspicious activity
🔍 How to Verify
Check if Vulnerable:
Check device firmware version against vendor advisory. Test if low-privilege user can modify other user passwords via iw_webs interface.Check Version:
Check via device web interface or CLI (vendor-specific command)Verify Fix Applied:
Verify firmware version matches patched version from vendor. Test that low-privilege users can no longer modify other user passwords.📡 Detection & Monitoring
Log Indicators:
- Unexpected user password changes
- Multiple failed login attempts followed by successful login from new IP
- User privilege escalation events
Network Indicators:
- Unusual SSH or telnet connections to industrial WLAN devices
- Traffic patterns suggesting device compromise
SIEM Query:
source="industrial_wlan" AND (event_type="user_modify" OR event_type="password_change")