CVE-2018-0253
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to execute arbitrary commands on Cisco Secure Access Control System (ACS) devices by sending malicious AMF messages. The commands run with the targeted user's privilege level, potentially leading to full system compromise. All Cisco Secure ACS releases prior to 5.8 Patch 7 are affected.
💻 Affected Systems
- Cisco Secure Access Control System (ACS)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with administrative privileges, data exfiltration, installation of persistent backdoors, and lateral movement to other network systems.
Likely Case
Remote code execution leading to service disruption, credential theft, and unauthorized access to sensitive authentication data stored in ACS.
If Mitigated
Limited impact if system is isolated, properly segmented, and monitored with intrusion detection systems in place.
🎯 Exploit Status
Exploitation requires sending crafted AMF messages to the vulnerable ACS Report component. Public exploit code exists.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Release 5.8 Patch 7 or later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180502-acs1
Restart Required: Yes
Instructions:
1. Download Cisco Secure ACS 5.8 Patch 7 or later from Cisco's software download center. 2. Backup current configuration. 3. Apply the patch following Cisco's installation guide. 4. Restart the ACS service or appliance as required.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to ACS devices to only trusted administrative networks
Access Control Lists
allImplement firewall rules to block unauthorized access to ACS Report component ports
🧯 If You Can't Patch
- Immediately isolate affected ACS systems from internet and untrusted networks
- Implement strict network monitoring and alerting for suspicious AMF traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check ACS version via web interface or CLI. If version is earlier than 5.8 Patch 7, system is vulnerable.Check Version:
show version (from ACS CLI) or check via web admin interfaceVerify Fix Applied:
Verify ACS version is 5.8 Patch 7 or later. Test AMF message handling functionality.📡 Detection & Monitoring
Log Indicators:
- Unusual AMF protocol traffic
- Failed authentication attempts to ACS Report component
- Unexpected process execution
Network Indicators:
- Malformed AMF messages to ACS Report ports
- Unusual outbound connections from ACS systems
SIEM Query:
source_ip="ACS_IP" AND (protocol="AMF" OR port="ACS_REPORT_PORT") AND (payload_contains="malicious_pattern" OR size>threshold)🔗 References
- http://www.securityfocus.com/bid/104075
- http://www.securitytracker.com/id/1040808
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180502-acs1
- http://www.securityfocus.com/bid/104075
- http://www.securitytracker.com/id/1040808
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180502-acs1
