CVE-2021-47740
📋 TL;DR
This vulnerability in KZTech JT3500V 4G LTE CPE devices allows attackers to reuse expired session credentials due to improper session expiration. Attackers can maintain unauthorized access to affected devices, potentially bypassing authentication controls. Organizations using KZTech JT3500V 4G LTE CPE version 2.0.1 are affected.
💻 Affected Systems
- KZTech JT3500V 4G LTE CPE
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to intercept network traffic, modify device configurations, or use the device as a pivot point into internal networks.
Likely Case
Unauthorized access to device administration interface leading to configuration changes, network disruption, or credential theft.
If Mitigated
Limited impact with proper network segmentation and monitoring, though authentication bypass remains possible.
🎯 Exploit Status
Exploitation requires initial authentication but allows session persistence after logout. Public exploit details available on Packet Storm Security.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: http://www.kzbtech.com/
Restart Required: Yes
Instructions:
1. Check vendor website for firmware updates. 2. Download latest firmware. 3. Upload to device via admin interface. 4. Apply update and restart device.
🔧 Temporary Workarounds
Session Timeout Enforcement
allImplement external session timeout and forced re-authentication
Network Segmentation
allIsolate CPE devices in separate network segments with strict access controls
🧯 If You Can't Patch
- Implement strict network access controls to limit device exposure
- Enable detailed logging and monitoring for unauthorized access attempts
🔍 How to Verify
Check if Vulnerable:
Check device firmware version in admin interface. If version is 2.0.1, device is vulnerable.Check Version:
Check via device web interface or SSH: cat /etc/version or similar firmware version fileVerify Fix Applied:
Verify firmware version has been updated beyond 2.0.1 and test session expiration by logging out and attempting to reuse old session tokens.📡 Detection & Monitoring
Log Indicators:
- Multiple successful logins from same session ID after logout
- Session tokens with extended lifetimes
- Authentication bypass attempts
Network Indicators:
- Unusual administrative access patterns
- Session reuse from previously logged-out IPs
SIEM Query:
source="cpe_logs" AND (event="session_reuse" OR (event="auth_success" AND session_age>3600))🔗 References
- http://www.kzbtech.com/
- https://exchange.xforce.ibmcloud.com/vulnerabilities/198471
- https://neotel.mk/
- https://packetstormsecurity.com/files/161892/
- https://www.jatontech.com/
- https://www.vulncheck.com/advisories/kztech-jtv-g-lte-cpe-insufficient-session-expiration-vulnerability
- https://www.zeroscience.mk/en/vulnerabilities/ZSL-2021-5646.php
