CVE-2021-1600
📋 TL;DR
CVE-2021-1600 allows unauthenticated attackers on the same network segment to bypass firewall restrictions on Cisco Intersight Virtual Appliance's external management interface. This enables access to internal services and potential configuration changes. Organizations using vulnerable versions of Cisco Intersight Virtual Appliance are affected.
💻 Affected Systems
- Cisco Intersight Virtual Appliance
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attacker gains full administrative control over the Intersight appliance, potentially compromising the entire managed infrastructure including UCS servers, HyperFlex systems, and other Cisco data center components.
Likely Case
Attacker accesses sensitive configuration data, modifies device settings, or disrupts management operations of connected Cisco infrastructure.
If Mitigated
With proper network segmentation and access controls, impact is limited to the management interface only, preventing lateral movement to managed systems.
🎯 Exploit Status
Exploitation requires sending specific IPv4/IPv6 packets to the external management interface from an adjacent network position.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.9-287 and later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ucsi2-iptaclbp-L8Dzs8m8
Restart Required: Yes
Instructions:
1. Download Intersight Virtual Appliance version 1.0.9-287 or later from Cisco Software Center. 2. Deploy the new OVA/OVF template. 3. Migrate configuration from old appliance. 4. Power down old appliance. 5. Verify new appliance is operational.
🔧 Temporary Workarounds
Network Segmentation
allRestrict access to the external management interface using network ACLs or firewall rules
Interface Restriction
allConfigure the appliance to only allow management from specific trusted IP addresses
🧯 If You Can't Patch
- Implement strict network segmentation to isolate the Intersight management interface from untrusted networks
- Deploy network monitoring and intrusion detection systems to detect exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check Intersight Virtual Appliance version via web interface or SSH: System > About in web UICheck Version:
ssh admin@intersight-appliance 'show version' or check web interface at System > AboutVerify Fix Applied:
Confirm version is 1.0.9-287 or later and test that external interface properly filters IPv4/IPv6 packets📡 Detection & Monitoring
Log Indicators:
- Unauthorized access attempts to internal services from external interface
- Unexpected configuration changes
Network Indicators:
- Unusual traffic patterns to internal service ports from external management interface
- IPv4/IPv6 packets bypassing expected firewall rules
SIEM Query:
source_interface="external-mgmt" AND dest_port IN (internal_service_ports) AND action="allow"