CVE-2021-47745
📋 TL;DR
CVE-2021-47745 is an authenticated command injection vulnerability in Cypress Solutions CTM-200 firmware that allows attackers with valid credentials to execute arbitrary shell commands with root privileges. The vulnerability exists in the firmware upgrade script where user input in the 'fw_url' parameter is not properly sanitized. Organizations using CTM-200 version 2.7.1 are affected.
💻 Affected Systems
- Cypress Solutions CTM-200
⚠️ 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 system compromise with root-level access, allowing attackers to install persistent backdoors, exfiltrate sensitive data, pivot to other network systems, or render the device inoperable.
Likely Case
Attackers with stolen or default credentials gain full control of the device, potentially using it as a foothold for lateral movement within the network.
If Mitigated
Limited impact if strong authentication controls, network segmentation, and input validation are properly implemented.
🎯 Exploit Status
Exploit code is publicly available on Exploit-DB and other sources. Attack requires valid credentials but execution is straightforward once authenticated.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check vendor for latest firmware version
Vendor Advisory: https://www.cypress.bc.ca
Restart Required: Yes
Instructions:
1. Contact Cypress Solutions for updated firmware. 2. Backup current configuration. 3. Upload and apply new firmware via management interface. 4. Verify successful update and restore configuration if needed.
🔧 Temporary Workarounds
Input Validation Enhancement
linuxAdd input validation to sanitize the fw_url parameter before processing
# Modify ctm-config-upgrade.sh to validate fw_url input
# Example: if [[ ! "$fw_url" =~ ^https?:// ]]; then exit 1; fi
Access Restriction
linuxRestrict access to the firmware upgrade functionality to trusted IP addresses only
# Add firewall rules to restrict access to management interface
iptables -A INPUT -p tcp --dport [management_port] -s [trusted_ip] -j ACCEPT
iptables -A INPUT -p tcp --dport [management_port] -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation to isolate CTM-200 devices from critical systems
- Enforce strong authentication policies including multi-factor authentication and regular credential rotation
🔍 How to Verify
Check if Vulnerable:
Check if CTM-200 is running version 2.7.1 via the web interface or SSH. Review the ctm-config-upgrade.sh script for lack of input validation on the fw_url parameter.Check Version:
ssh admin@[device_ip] 'cat /etc/version' or check via web interfaceVerify Fix Applied:
Verify firmware version has been updated beyond 2.7.1. Test the firmware upgrade functionality with malicious input to confirm proper input validation.📡 Detection & Monitoring
Log Indicators:
- Unusual firmware upgrade attempts
- Suspicious commands in system logs following firmware upgrade requests
- Multiple failed authentication attempts followed by successful login
Network Indicators:
- Unusual outbound connections from CTM-200 device
- Traffic to unexpected destinations following firmware upgrade requests
SIEM Query:
source="ctm-200" AND (event="firmware_upgrade" AND url="*;*" OR url="*|*" OR url="*`*" OR url="*$(*)")