CVE-2018-0310
📋 TL;DR
A buffer overread vulnerability in Cisco Fabric Services allows unauthenticated remote attackers to read sensitive memory contents or cause denial of service on affected Cisco networking devices. This affects numerous Cisco switches, firewalls, and fabric interconnects running vulnerable FXOS or NX-OS software. The vulnerability has a critical CVSS score of 9.8 due to its network-accessible nature and lack of authentication requirements.
💻 Affected Systems
- Firepower 4100 Series Next-Generation Firewalls
- Firepower 9300 Security Appliance
- MDS 9000 Series Multilayer Switches
- Nexus 2000 Series Fabric Extenders
- Nexus 3000 Series Switches
- Nexus 3500 Platform Switches
- Nexus 5500 Platform Switches
- Nexus 5600 Platform Switches
- Nexus 6000 Series Switches
- Nexus 7000 Series Switches
- Nexus 7700 Series Switches
- Nexus 9000 Series Switches in standalone NX-OS mode
- Nexus 9500 R-Series Line Cards and Fabric Modules
- UCS 6100 Series Fabric Interconnects
- UCS 6200 Series Fabric Interconnects
- UCS 6300 Series Fabric Interconnects
📦 What is this software?
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Firepower Extensible Operating System by Cisco
View all CVEs affecting Firepower Extensible Operating System →
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
Nx Os by Cisco
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker gains sensitive information from device memory (potentially including credentials, configuration data, or other secrets) and crashes the device, causing complete network outage.
Likely Case
Remote attacker causes denial of service by crashing the affected device, disrupting network connectivity and services.
If Mitigated
With proper network segmentation and access controls, impact is limited to isolated network segments with minimal business disruption.
🎯 Exploit Status
Exploitation requires sending crafted Cisco Fabric Services packets to vulnerable devices. No authentication is required, making exploitation straightforward for attackers with network access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Refer to Cisco Security Advisory for specific fixed versions per product
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180620-nx-os-fabric-dos
Restart Required: Yes
Instructions:
1. Review Cisco Security Advisory for affected versions and fixed releases
2. Download appropriate fixed software from Cisco.com
3. Schedule maintenance window for device reboot
4. Apply software update following Cisco upgrade procedures
5. Verify successful update and functionality
🔧 Temporary Workarounds
Disable Cisco Fabric Services
allTemporarily disable Cisco Fabric Services on affected devices if not required for operation
feature disable fabric-services
Implement Access Control Lists
allRestrict access to Cisco Fabric Services ports (typically TCP 3225) to trusted sources only
access-list name permit tcp trusted-source any eq 3225
access-list name deny tcp any any eq 3225
apply access-list to appropriate interfaces
🧯 If You Can't Patch
- Segment affected devices in isolated network zones with strict firewall rules
- Monitor network traffic for anomalous Cisco Fabric Services packets and implement intrusion detection
🔍 How to Verify
Check if Vulnerable:
Check device software version against affected versions listed in Cisco Security AdvisoryCheck Version:
show versionVerify Fix Applied:
Verify device is running fixed software version from Cisco advisory and Cisco Fabric Services is functioning properly📡 Detection & Monitoring
Log Indicators:
- Unexpected device crashes or reboots
- Cisco Fabric Services error messages
- Memory access violation logs
Network Indicators:
- Anomalous traffic to TCP port 3225
- Malformed Cisco Fabric Services packets
- Unusual traffic patterns from untrusted sources to affected devices
SIEM Query:
source_port:3225 OR dest_port:3225 AND (protocol:TCP) AND (anomalous_size OR malformed_packet)