CVE-2021-27505
📋 TL;DR
CVE-2021-27505 is an information disclosure vulnerability in mySCADA myPRO software where unauthorized users can access sensitive directory listings. This exposes internal system information that could aid attackers in further exploitation. Organizations using mySCADA myPRO versions before 8.20.0 are affected.
💻 Affected Systems
- mySCADA myPRO
📦 What is this software?
Mypro by Myscada
⚠️ Risk & Real-World Impact
Worst Case
Attackers obtain complete directory structure, configuration files, and sensitive data, enabling reconnaissance for more severe attacks like credential theft or system compromise.
Likely Case
Unauthorized access to directory listings reveals system architecture, file paths, and potentially configuration details that could be leveraged for targeted attacks.
If Mitigated
With proper network segmentation and access controls, impact is limited to information disclosure without direct system compromise.
🎯 Exploit Status
Exploitation requires only web access to the vulnerable endpoint; no authentication or special tools needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 8.20.0
Vendor Advisory: https://www.myscada.org/version-8-20-0-released-security-update
Restart Required: Yes
Instructions:
1. Download mySCADA myPRO version 8.20.0 or later from official vendor site. 2. Backup current configuration and data. 3. Install the update following vendor documentation. 4. Restart the myPRO service/application.
🔧 Temporary Workarounds
Network Access Restriction
allRestrict network access to myPRO web interface using firewall rules to only allow trusted IP addresses.
Web Server Configuration
allConfigure web server to disable directory listing for sensitive paths if supported by the application.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate myPRO systems from untrusted networks
- Deploy web application firewall (WAF) rules to block directory listing requests
🔍 How to Verify
Check if Vulnerable:
Access the myPRO web interface and attempt to browse to directory listing endpoints; if directory contents are displayed without authentication, system is vulnerable.Check Version:
Check version in myPRO web interface admin panel or consult application documentation for version commandVerify Fix Applied:
After updating to 8.20.0+, attempt the same directory listing access; should receive access denied or proper error message.📡 Detection & Monitoring
Log Indicators:
- HTTP requests to directory listing endpoints (e.g., /directory/, /files/) with 200 OK responses
- Multiple failed authentication attempts followed by directory access
Network Indicators:
- Unusual HTTP GET requests to paths that typically contain sensitive directories
- Traffic from unexpected sources to myPRO web ports
SIEM Query:
source="mypro_logs" AND (url_path="*/directory/*" OR url_path="*/files/*") AND http_status=200