CVE-2021-31349
📋 TL;DR
This CVE describes an authentication bypass vulnerability in Juniper Networks 128 Technology Session Smart Router where an attacker can use an internal HTTP header to bypass authentication. This allows attackers to view internal files, change settings, manipulate services, and execute arbitrary code. All versions prior to 4.5.11 and all 5.0 versions up to and including 5.0.1 are affected.
💻 Affected Systems
- Juniper Networks 128 Technology Session Smart Router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with root-level arbitrary code execution, configuration manipulation, and data exfiltration
Likely Case
Unauthorized access to sensitive configuration files, service manipulation, and potential lateral movement
If Mitigated
Limited impact if proper network segmentation and access controls prevent exploitation attempts
🎯 Exploit Status
Exploitation requires sending specially crafted HTTP requests with internal headers
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.5.11 or 5.0.2
Vendor Advisory: https://kb.juniper.net/JSA11256
Restart Required: Yes
Instructions:
1. Download the patched version from Juniper support portal. 2. Backup current configuration. 3. Install the update following Juniper's upgrade procedures. 4. Reboot the router. 5. Verify the new version is running.
🔧 Temporary Workarounds
Network Access Restriction
allRestrict access to the router's management interface to trusted IP addresses only
Configure firewall rules to limit access to router management IP/ports
🧯 If You Can't Patch
- Isolate affected routers in separate network segments with strict access controls
- Implement network monitoring for suspicious HTTP requests to router management interfaces
🔍 How to Verify
Check if Vulnerable:
Check router version via CLI: show versionCheck Version:
show versionVerify Fix Applied:
Verify version is 4.5.11 or higher, or 5.0.2 or higher📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to management interface
- Authentication bypass attempts
- Configuration changes from unauthorized sources
Network Indicators:
- HTTP requests with unusual headers to router management ports
- Traffic patterns indicating unauthorized access
SIEM Query:
source="router_logs" AND (http_header="*internal*" OR auth_bypass="true")