CVE-2021-1134
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to intercept and modify sensitive network client data by exploiting improper X.509 certificate validation between Cisco DNA Center and Identity Services Engine. Organizations using Cisco DNA Center with ISE integration are affected. Attackers can view and alter client information maintained by ISE.
💻 Affected Systems
- Cisco DNA Center Software
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain persistent access to intercept all communications between DNA Center and ISE, allowing them to view and modify sensitive client data, potentially compromising network security and client privacy.
Likely Case
Attackers intercept specific communications to gather sensitive client information or manipulate network access policies, leading to data exposure or unauthorized network access.
If Mitigated
With proper network segmentation and monitoring, impact is limited to potential data exposure without direct system compromise.
🎯 Exploit Status
Exploitation requires the attacker to be in a position to intercept and manipulate network traffic between DNA Center and ISE, and to craft a specific X.509 certificate.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Cisco DNA Center Software Release 1.3.3.6 or later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-dnac-certvalid-USEj2CZk
Restart Required: Yes
Instructions:
1. Download the patch from Cisco Software Center. 2. Apply the update through the DNA Center GUI or CLI. 3. Restart the DNA Center appliance as required. 4. Verify the update completed successfully.
🔧 Temporary Workarounds
Disable ISE Integration
allTemporarily disable the ISE integration feature in DNA Center to prevent exploitation.
Navigate to System > Settings > External Services > ISE and disable integration
Network Segmentation
allIsolate DNA Center and ISE communication to trusted network segments only.
Configure firewall rules to restrict access to DNA Center-ISE communication ports
🧯 If You Can't Patch
- Implement strict network segmentation between DNA Center and ISE servers
- Monitor network traffic for unusual certificate activity and connection attempts
🔍 How to Verify
Check if Vulnerable:
Check DNA Center version via GUI (System > About) or CLI command 'show version' and verify if version is prior to 1.3.3.6 with ISE integration enabled.Check Version:
show versionVerify Fix Applied:
Confirm DNA Center version is 1.3.3.6 or later and verify ISE integration functions normally without certificate validation issues.📡 Detection & Monitoring
Log Indicators:
- Failed certificate validation logs
- Unexpected certificate authority changes
- Unusual connection attempts between DNA Center and ISE
Network Indicators:
- Unusual traffic patterns between DNA Center and ISE servers
- Certificate validation failures in network traffic
SIEM Query:
source="dna-center" AND (event_type="certificate_validation_failure" OR event_type="ise_connection_error")