CVE-2021-34735
📋 TL;DR
This vulnerability in Cisco ATA 190 Series Analog Telephone Adapters allows attackers to execute arbitrary commands on affected devices through command injection. Successful exploitation could lead to remote code execution or denial of service. Organizations using Cisco ATA 190 devices with vulnerable software versions are affected.
💻 Affected Systems
- Cisco ATA 190 Series Analog Telephone Adapter
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full device compromise allowing attacker to execute arbitrary code, pivot to internal networks, and maintain persistent access.
Likely Case
Remote code execution leading to device takeover, configuration changes, or denial of service disrupting telephony services.
If Mitigated
Limited impact through network segmentation and access controls preventing exploitation attempts.
🎯 Exploit Status
Command injection vulnerabilities typically have low exploitation complexity once details are known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Version 11.2.1 or later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ata19x-multivuln-A4J57F3
Restart Required: Yes
Instructions:
1. Download firmware version 11.2.1 or later from Cisco. 2. Upload firmware to ATA device via web interface. 3. Apply firmware update. 4. Reboot device to complete installation.
🔧 Temporary Workarounds
Network Segmentation
allIsolate ATA devices from untrusted networks and restrict access to management interfaces.
Access Control Lists
allImplement firewall rules to restrict access to ATA devices to authorized IP addresses only.
🧯 If You Can't Patch
- Segment ATA devices on isolated VLANs with strict firewall rules
- Monitor network traffic to/from ATA devices for suspicious activity
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: System Information > Software VersionCheck Version:
Check via web interface or SSH: show versionVerify Fix Applied:
Verify firmware version is 11.2.1 or later in System Information📡 Detection & Monitoring
Log Indicators:
- Unusual command execution in system logs
- Multiple failed authentication attempts
- Unexpected configuration changes
Network Indicators:
- Unusual outbound connections from ATA devices
- Traffic to unexpected ports
- Suspicious HTTP requests to management interface
SIEM Query:
source="cisco_ata" AND (event_type="command_execution" OR event_type="config_change")