CVE-2020-7847
📋 TL;DR
CVE-2020-7847 is an arbitrary file upload vulnerability in ipTIME NAS devices that allows attackers to upload malicious files through the Manage Bulletins/Upload feature. This can lead to remote code execution on the affected NAS system. The vulnerability specifically affects ipTIME NAS version 1.4.36.
💻 Affected Systems
- ipTIME NAS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining root access, data theft, ransomware deployment, and use as pivot point to attack internal networks.
Likely Case
Remote code execution leading to data exfiltration, installation of backdoors, or cryptomining malware.
If Mitigated
Limited impact if proper network segmentation and access controls prevent external exploitation.
🎯 Exploit Status
Exploitation requires authentication to the NAS management interface. The vulnerability is in the file upload functionality which can be abused to upload webshells or malicious scripts.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Later versions than 1.4.36
Vendor Advisory: https://www.boho.or.kr/krcert/secNoticeView.do?bulletin_writing_sequence=35921
Restart Required: Yes
Instructions:
1. Log into ipTIME NAS web interface. 2. Navigate to System Management > Firmware Update. 3. Check for and apply the latest firmware version. 4. Reboot the NAS after update completes.
🔧 Temporary Workarounds
Disable Bulletin Upload Feature
allTemporarily disable the vulnerable Manage Bulletins/Upload feature until patching is possible.
No CLI commands available - must be done through web interface
Restrict Network Access
linuxLimit access to NAS management interface to trusted IP addresses only.
iptables -A INPUT -p tcp --dport 80 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Isolate the NAS on a separate VLAN with strict firewall rules
- Implement multi-factor authentication for NAS management access
🔍 How to Verify
Check if Vulnerable:
Check firmware version in NAS web interface under System Information. If version is exactly 1.4.36, the system is vulnerable.Check Version:
No CLI command - check via web interface at System > InformationVerify Fix Applied:
Verify firmware version has been updated to a version higher than 1.4.36 and test the bulletin upload functionality with safe test files.📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads to bulletin management endpoint
- Multiple failed authentication attempts followed by successful login and file upload
- Execution of unexpected scripts or binaries
Network Indicators:
- HTTP POST requests to bulletin upload endpoints with unusual file extensions
- Outbound connections from NAS to suspicious external IPs
SIEM Query:
source="nas_logs" AND (uri_path="/cgi-bin/bulletin_upload" OR uri_path="/upload") AND (file_extension="php" OR file_extension="jsp" OR file_extension="asp")