CVE-2020-23043
📋 TL;DR
Tran Tu Air Sender v1.0.2 contains an arbitrary file upload vulnerability in its upload module that allows attackers to upload malicious files and execute arbitrary code on the system. This affects all users running the vulnerable version of this software. The vulnerability is particularly dangerous because it can lead to complete system compromise.
💻 Affected Systems
- Tran Tu Air Sender
📦 What is this software?
Air Sender by Air Sender Project
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with remote code execution, data theft, ransomware deployment, and lateral movement within the network.
Likely Case
Webshell installation leading to persistent backdoor access, data exfiltration, and potential privilege escalation.
If Mitigated
File upload attempts blocked at perimeter, limited impact to isolated system with proper segmentation.
🎯 Exploit Status
Simple file upload bypass techniques can be used. No authentication required. Exploit tools likely exist in underground forums.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: No official vendor advisory found
Restart Required: No
Instructions:
1. Check for updated version from vendor
2. If no patch available, implement workarounds
3. Consider replacing with alternative software
🔧 Temporary Workarounds
Web Application Firewall (WAF) Rules
allBlock malicious file uploads at the perimeter
Configure WAF to block file uploads with executable extensions
Implement file type validation rules
File Upload Restrictions
allRestrict upload functionality in the application
Disable upload module if not needed
Implement strict file type validation (whitelist approach)
Set upload directory with no execute permissions
🧯 If You Can't Patch
- Network segmentation: Isolate the system in a restricted VLAN
- Implement strict outbound firewall rules to prevent data exfiltration
🔍 How to Verify
Check if Vulnerable:
Check software version. If running v1.0.2, assume vulnerable. Test by attempting to upload a file with executable extension.Check Version:
Check application interface or configuration files for version informationVerify Fix Applied:
Attempt to upload malicious file after implementing controls. Verify file is rejected or placed in non-executable location.📡 Detection & Monitoring
Log Indicators:
- Unusual file uploads to upload directory
- Files with executable extensions in upload folder
- Webshell access patterns in web logs
Network Indicators:
- Outbound connections from the server to unknown IPs
- Unusual traffic patterns from the application server
SIEM Query:
source="web_logs" AND (uri CONTAINS "/upload" OR file_extension IN ("php", "jsp", "asp", "exe", "sh"))