CVE-2021-22719
📋 TL;DR
This path traversal vulnerability in Schneider Electric's C-Bus Toolkit allows attackers to upload malicious files to arbitrary locations on the system, potentially leading to remote code execution. It affects C-Bus Toolkit versions 1.15.7 and earlier. Organizations using this building automation software for configuration and management are at risk.
💻 Affected Systems
- Schneider Electric C-Bus Toolkit
📦 What is this software?
C Bus Toolkit by Schneider Electric
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining complete control over the C-Bus system, potentially enabling lateral movement to other building automation systems or corporate networks.
Likely Case
Remote code execution allowing attackers to manipulate building automation systems, disrupt operations, or deploy ransomware on affected systems.
If Mitigated
Limited impact with proper network segmentation and access controls preventing exploitation attempts from reaching vulnerable systems.
🎯 Exploit Status
The vulnerability requires authentication but has been assigned a high CVSS score due to the potential impact. ZDI has published an advisory indicating active research.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.15.8 or later
Vendor Advisory: https://download.schneider-electric.com/files?p_Doc_Ref=SEVD-2021-103-01
Restart Required: Yes
Instructions:
1. Download C-Bus Toolkit version 1.15.8 or later from Schneider Electric's website. 2. Backup existing configurations. 3. Uninstall previous version. 4. Install updated version. 5. Restart the system.
🔧 Temporary Workarounds
Network Segmentation
allIsolate C-Bus Toolkit systems from untrusted networks and restrict access to authorized users only.
Access Control Hardening
allImplement strict authentication requirements and limit user privileges for C-Bus Toolkit access.
🧯 If You Can't Patch
- Implement network-level controls to restrict access to C-Bus Toolkit systems to only authorized management stations
- Deploy application whitelisting to prevent execution of unauthorized files on affected systems
🔍 How to Verify
Check if Vulnerable:
Check C-Bus Toolkit version in Help > About menu. If version is 1.15.7 or earlier, the system is vulnerable.Check Version:
Check Help > About menu in C-Bus Toolkit applicationVerify Fix Applied:
After patching, verify version shows 1.15.8 or later in Help > About menu. Test file upload functionality with path traversal attempts.📡 Detection & Monitoring
Log Indicators:
- Unusual file upload attempts to C-Bus Toolkit
- Failed authentication attempts followed by file upload requests
- Execution of unexpected files on C-Bus systems
Network Indicators:
- HTTP POST requests to C-Bus Toolkit with path traversal patterns in filenames
- Unusual outbound connections from C-Bus systems
SIEM Query:
source="C-Bus Toolkit" AND (event="file_upload" OR event="authentication") AND (filename="..\\" OR filename="../")