CVE-2021-39290
📋 TL;DR
This vulnerability allows session fixation attacks on NetModule networking devices, enabling attackers to hijack user sessions by setting a known PHPSESSID. Affected are multiple NetModule router models running outdated firmware versions before specified security updates.
💻 Affected Systems
- NB800
- NB1600
- NB1601
- NB1800
- NB1810
- NB2700
- NB2710
- NB2800
- NB2810
- NB3700
- NB3701
- NB3710
- NB3711
- NB3720
- NB3800
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing administrative access, configuration changes, network traffic interception, and potential lateral movement to connected systems.
Likely Case
Unauthorized access to device management interface leading to configuration tampering, service disruption, or credential theft.
If Mitigated
Limited impact with proper network segmentation, strong authentication, and monitoring in place.
🎯 Exploit Status
Exploitation requires initial access to set session ID but is technically simple once that condition is met.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware 4.3.0.113, 4.4.0.111, or 4.5.0.105 and later
Vendor Advisory: https://www.netmodule.com
Restart Required: Yes
Instructions:
1. Download latest firmware from NetModule support portal. 2. Backup current configuration. 3. Upload firmware via web interface or CLI. 4. Apply update and restart device. 5. Verify new firmware version.
🔧 Temporary Workarounds
Network Segmentation
allIsolate management interfaces from untrusted networks
Session Management Hardening
allImplement additional session validation and timeout policies
🧯 If You Can't Patch
- Restrict management interface access to trusted IP addresses only
- Implement multi-factor authentication for administrative access
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface (System > Status) or CLI command 'show version'Check Version:
show versionVerify Fix Applied:
Confirm firmware version is 4.3.0.113, 4.4.0.111, 4.5.0.105 or higher📡 Detection & Monitoring
Log Indicators:
- Multiple session IDs from same IP
- Session fixation attempts in access logs
- Unauthorized configuration changes
Network Indicators:
- Unusual management interface traffic patterns
- Session ID manipulation attempts
SIEM Query:
source="netmodule" AND (event="session_fixation" OR event="auth_bypass")